Several dogs at a Miami humane society were quarantined last week because of concerns (or possibly panic/over-reaction) about methicillin-resistant Staphylococcus aureus (MRSA). MRSA in dogs is a concern because it's an important cause of infection in both people and animals. However, it's an opportunist, meaning it typically doesn't cause disease when it encounters a normal, healthy person or animal. In fact, a small percentage (~1-3% probably) of the human and pet populations carry this bacterium in their nose without knowing it, and the vast majority never suffer any consequences.
It's often tough to strike the right balance when dealing with an MRSA issue. We want people to realize that it's an important cause of disease and that it needs to be taken seriously, but we also want people to keep it in perspective and not freak out.
The Miami shelter report seems to be on the "freak out" side, particularly on the part of the local media.
It's not really clear what's happening based on this fairly poor article. The shelter's Chief Medical Officer, Dr. Maureen Swan, is quoted as saying there's a routine respiratory disease cluster in the shelter, but MRSA rarely causes respiratory disease in dogs. The article then adds Dr. Swan said it was "not the highly contagious MRSA virus." I have no idea what that means, and MRSA is not a virus.
My suspicion is that they have respiratory disease caused by the typical bacterial and/or viral pathogens that are commonly found in shelter dogs, and that they isolated a methicillin-resistant staph that just happened to be hanging around in that particular dog (since such bacteria normally live in the mouth, nose and skin). It's also not really clear whether this is MRSA. The article says MRSA, but the first thing I ask when I get an advice call about MRSA is "what staph species does the report say was isolated?". Most often, it's Staphylococcus pseudintermedius or another staph. These bugs can still be relevant, but they don't carry the same human health risk as MRSA, so it's important to know exactly what's been found.
Finding MR staph, including MRSA, isn't unheard of in a shelter. It's just one of many reasons that good general infection control practices are needed in these facilities. When MRSA is found, taking some extra precautions is reasonable because of the potential for disease and transmission to people, but too often people panic. It's understandable based on concern about MRSA and the scary stories people can find with a quick Google search. Not uncommonly, there's a combination of an short-term overly aggressive response while at the same time failing to improve basic infection control practices, which are the most important.
More information about MRSA can be found on the Worms & Germs Resources - Pets page.
The latest edition of the University of Guelph Animal Health Laboratory's newsletter contains an interesting report about 4 horses that died over the past few years from what was suspected to be contaminated intravenous fluid solutions. These cases were dead horses that were submitted for post-mortem examination from three different farms, so if anything, this could be an underestimation of the problem.
The first two horses were from the same farm. They were young Thoroughbreds that were routinely treated with intravenous electrolytes, vitamins and minerals (whether by the trainer or veterinarian is unknown). The first horse was found with its head hanging low after treatment. It later developed seizures and died. The second horse showed similar signs. The bacterium Klebsiella pneumoniae was isolated from a few different tissues of the first horse, as well as one of the "jugs" used to administer the fluids. The second horse had the same general lesions as the first, but Klebsiella wasn't isolated; however, this may have been because the body wasn't in great shape by the time it was submitted to the lab, and various other bacteria had overgrown the Klebsiella, making it difficult to isolate.
Another case was a young Standardbred that died after receiving intravenous fluids with vitamins, and a glyceryl guaiacolate jug. It had signs of bloodstream infection (septicemia) and Klebsiella oxytoca was isolated from multiple organs. Various bacteria were isolated from remnants of fluid in treatment bottles.
The final case was a five-year-old Standardbred that died after receiving a home-mixed vitamin jug. It had lesions similar to the other horses and consistent with a bloodstream infection. Klebsiella oxytoca was isolated from multiple organs.
Contamination of multidose drug vials or fluid solutions can occur if bacteria are inoculated into the bottle with a needle when a dose if withdrawn. We've shown this happens with multidose vials in a hospital situation, and of the farm it's even more likely to occur because it's a dirtier environment and, in the case of farm personnel, individuals have less experience with sterile technique. Fluid solutions can be contaminated in the same manner or when something is added to the fluids (e.g. vitamins). Contamination of reused fluid administration sets (i.e. fluid jugs/bags and the IV tubing) is quite likely, and that's why use of sterlie, single-use administration sets is recommended. Adverse events from a little bit of contamination are uncommon, but as shown here, they can happen and they can be severe. There's no information about what contributed to the contamination in these cases, but it's almost certain that poor infection control practices were at the root of the problem. Trying to save money by skimping on sterilization, reusing items without proper care, and using poor hygiene practices in general can end up costing much more.
An abstract for the upcoming CSTE (Council of State and Territorial Epidemiologists) conference in California describes a rare but concerning case of Brucella canis infection in a child. All I have to go by is the abstract (since the meeting hasn’t happened yet and I won’t be there anyway), but it provides an interesting outline.
Brucella canis is a bacterium that is (not surprisingly, given the name) associated with dogs. It’s present in dogs internationally, with higher rates of infection in strays and shelter dogs. It can cause a variety of problems in dogs, most often abortion, stillbirth and birth of weak puppies, but also things like reproductive failure and genital inflammation in males, and diskospondylitis (a kind of back problem). After a dog gets infected, the bacterium can localize to genital tissues, where it tends to hang out, resulting in intermittent shedding of B. canis in urine, vaginal discharge, fetal fluids, semen and, to a lesser extent, some other tissues. Humans can then be exposed via contact with these fluids. The main risk to humans comes from handling breeding dogs, particularly female dogs that have aborted puppies. However, people seem to be relatively resistant to B. canis infection, and there are actually only a small number of reports of human infections with this bacterium.
The risk to average pet owners is very low, but as this report shows, low doesn’t mean zero. This abstract deals with an infection in a 3-year-old child from New York city. The family had acquired a Yorkshire terrier puppy from a local store in March 2012. As is expected, there was close contact between the child and the puppy.
Near the end of April, the child was taken to an emergency room because of fever and difficulty breathing. Bacterial infection wasn’t the main suspect and he was discharged without antibiotics (presumably having improved from how he was at the time of admission). However, a blood culture was collected and it came back positive for Brucella canis. While the boy had been doing well, he was treated with 45 days of antibiotics to try to make sure the bacterium was eliminated, since it can cause chronic problems.
In a step that’s too often overlooked in zoonotic disease occurrences, there was an investigation of the source. That’s not surprising since this is a rare and concerning bacterium, and it’s pretty clear that pet contact tracing is required. The puppy was healthy but the bacterium was isolated from its blood. Because of the test result, the puppy was euthanized. (There’s no mention of whether this was at the owner’s request or based on the recommendation of public health personnel.)
The source of the puppy was a major concern, since it’s important to make sure that there aren’t other infected puppies around. The puppy came from a "commercial breeding facility" in Iowa - yet another instance of the potential for widespread national and international distribution of pathogens from large commercial pet operations. The facility was quarantined but there’s no more information in the abstract about whether other positive animals were found, whether infected puppies may have been sent elsewhere in the country, and what measures were taken to correct the problem.
A littermate of the New York puppy was sold by the same store. It also tested positive for B. canis and was treated.
This is a rare incident, but it highlights some points for me:
- Large commercial breeding facilities for dogs are unnecessary and create increased risk of disease in animals and by extension people. Yes, this could occur with a small private breeder, but the more animals, the more risk of infectious disease, and the larger the facility, the larger the potential impact should a disease issue develop.
- Proper counseling of people whose pets are diagnosed with a zoonotic pathogen is needed. I don’t know the story at all about why the first puppy was euthanized, but it might have been avoidable. What to do with animals that are healthy but shedding potentially concerning pathogens is a tough area to address. That’s particularly true for a bug like B. canis, since it can be hard to eliminate.
- Good communication is needed between the medical field, public health, veterinary medicine and the public. It’s hard to say how smoothly this investigation actually went, but it shows a good response to a rare but potentially serious problem.
- People that sell animals need to keep accurate contact information from purchasers. It’s good to see that they were able to track down the owners of the original puppy's infected littermate. Contact tracing is important with infectious diseases and it can be exceedingly difficult at times.
- There’s an inherent risk in pet ownership. We know that and have to accept it. The child was high risk because of his age. That doesn’t mean we don’t let kids have pets, but we have to understand the risk and use some basic hygiene practices to reduce that risk. Would it have had any impact on this case? Who knows, but it never hurts to improve.
I’ve written about the African dwarf frog and Salmonella issue before, but it’s worth a recap since an overview of the 2008-2011 outbreak was recently published in the journal Pediatrics (Mettee Zarecki et al 2013). The fact that reptiles and amphibians can carry Salmonella is nothing new, nor is the fact that outbreaks of disease can occur in people who have contact with them. However, the scale of outbreaks associated with pets can be impressive.
Here are some highlights from the paper:
- Between January 1, 2008 and December 31, 2011, 376 people were diagnosed with salmonellosis caused by the outbreak strain, a type of Salmonella Typhimurium.
- As is common in pet-associated outbreaks, kids bore the brunt of this one. The mean age of infected individuals was 5 years, and 69% were children under the age of 10.
- Severe disease wasn’t uncommon - 29% of people were hospitalized, half of those being kids less than 5 years of age. Fortunately, no one died.
- During a preliminary study, when they compared people who got sick with a group of healthy controls, they found that people who reported exposure to any aquatic pet were almost 5 times as likely to have salmonellosis. When that was narrowed down to exposure to just frogs, the risk went up to 12.4 times higher than healthy controls.
- When they looked at people who were sick and reported exposure to frogs, only 27% reported having touched a frog, with 46% reporting having fed a frog, 59% having had contact with a frog’s habitat and 60% having had contact with water from a frog’s habitat. Twenty-three percent (23%) reported cleaning the frog’s habitat in the kitchen sink, and 35% in the bathroom sink. This tells us some very important information. It tells us that direct contact with frogs or their environment is a high risk behaviour. However, direct contact isn’t required to get sick. While the frog may stay in its habitat, Salmonella may not. Cleaning habitats in kitchen or bathroom sinks is a high risk activity, because it can result in contamination of common human-touch surfaces and items that go into peoples’ mouths (e.g. toothbrushes, cups).
- Often, disease occurred not long after a new frog was obtained. The median time from purchase of a frog to disease was 30 days (range 5-2310 days).
- Only 17% of people interviewed reported knowing that frogs can carry Salmonella. Over twice as many knew there was a risk from reptiles. This shows there needs to be more education of people who buy animals such as frogs. Pet stores should be required to provide some basic public health information. Pet owners should also take initiative and research potential new pets, including how to care for them and how to reduce the risk of zoonotic infection.
- The outbreak Salmonella strain was found in the environment of some patient homes (not surprisingly), an African dwarf frog vendor (potential source of infection), a large-scale African dwarf frog distributor (a great way to spread an outbreak across the continent) and a daycare centre (that never should have had an amphibian in the first place!).
- One breeding facility in California was the likely source. With centralized, large-scale breeding and warehouse-style distribution of pets (of various species, not just frogs), we’re seeing more large-scale outbreaks like this.
More information about African dwarf frogs can be found on the Worms & Germs Resources - Pets page.
As if horse owners and veterinarians in Queensland need another infectious disease challenge.....
Recently, a horse in southwest Queensland was diagnosed with Australian bat lyssavirus infection. This virus, which is similar to rabies, is present in some bats in Australia. It can be transmitted to people from bats, causing fatal disease, but human infections are very rare. Even though it's rare, it warrants attention because the disease is so severe.
Finding an infected horse is surprising in some ways, because the virus has never been detected in this species before. However, a virus that's present in bats can certainly find its way into a horse, and we already knew that a closely related virus (rabies) can infect horses. So, maybe it's not that surprising afterall.
In this case, the horse was suspected of being infected with Hendra virus initially. While Australian bat lyssavirus can kill people, this diagnosis was actually much better than Hendra virus infection, because horse-human transmission of Hendra is a major concern. Hendra virus infections have high fatality rates and, perhaps most importantly, there are no effective preventative measures that can be taken after Hendra virus exposure. Since Australian bat lyssavirus is so closely related to rabies virus, rabies post-exposure treatment can be used in this case (and is probably effective).
It's unclear whether an infected horse poses much risk to people. The very small number of human Australian bat lyssavirus cases have occured in people who were bitten or scratched by bats. Since this is the first equine case, it's not known if affected horses shed large amounts of (or any) virus. People who had contact with the horse were identified and offered post-exposure treatment. It's reasonable to consider this situation like rabies exposure in the absence of more evidence, and treat people who were bitten or otherwise may have gotten virus-contaminated saliva into their tissues via broken skin or mucous membranes.
Is this the start of yet another new problem?
Most likely, this is just an example of the rare scenario of a virus infecting an atypical host, not the start of a new, common problem. However, it's worthy of attention in case the virus has changed or there is now a specific virus type that can more easily infect horses (both very unlikely). This case also shows the importance of thorough diagnostic testing, particularly when an animal has severe disease.
If you don't look, you don't find.
If you don't find, you can't act.
We've just posted a new info sheet about cat scratch disease (CSD), which is caused by a bacterium (Bartonella henselae) commonly carried in the bloodstream of healthy cats. Signs of CSD in people can be quite non-specific, so (as always) it's important to let your physician know if you've been bitten or scratched by a cat if you're feeling ill, so that CSD is considered. Other than proper training and handling of cats to avoid bites and scratches, the next most important component of CSD prevention is flea control.
You can read more about CSD and B. henselae on the new info sheet, which you can find along with all our other info sheets on the Worms & Germs Resources - Pets page. You can also read about CSD in the posts in our archives.
I have three kids that are all now (thankfully) past the diaper stage. I have no idea how many diapers I changed, but I don't have a huge desire to start doing it again, especially for chickens.
I understand the whole urban chicken concept. I don't actually have many issues with it if it's done right - but that's a big IF, unfortunately. Keep your chickens on your property, don't do it if you have young kids or other high risk individuals in the household, use good basic hygiene practices, feed them right, don't get roosters, and don't run screaming to the newspapers or local politicians if some get eaten by carnivorous urban wildlife. The nuisance and risk of backyard poultry can be limited.
Live chickens inside the house... that's another story.
Chickens aren't house pets in my world. I'm not sure if the chickens benefit at all from living in a house with people, and it's probably actually detrimental in many ways. I'm not sure what the benefit is to people either. Although I haven't seen any studies on this specific topic, it stands to reason that keeping a chicken indoors would be associated with a fairly high risk of widespread contamination of the household with bacteria like Salmonella and Campylobacter, two bugs that cause millions of infections in humans every year.
I'm all for risk mitigation, including using creative (and sometimes off-the-wall) measures - but diapers for chickens? Not so much.
Yet, Pampered Poultry makes diapers for your indoor chickens, and not just run-of-the-mill diapers: they're (allegedly) both functional and fashionable. This isn't the only company that sells chicken diapers either, much to my surprise.
One website states "Our chicken diapers are not just for the fashion obsessed hen. They offer your and your home protection against the inevitable! Our diapers fit comfortably and allow you to enjoy your birds in the house or car [car?] without worry."
Does using chicken diapers make sense?
I have a hard time believing these diapers are very useful. They probably do reduce the burden of pathogens that are deposited in the environment, but they are presumably far from 100% effective at containing all of a bird's droppings. It's also likely that chickens are contaminated with these bacteria on other parts of their bodies. Thinking you've eliminated the risk of household contamination from your pet poultry by using diapers isn't logical. The diapers also need to be changed (risk of more contamination) and disposed (don't we have enough waste already?) or washed (risk of cross-contaminating other items).
If you want fashionable chickens, go ahead and dress them up in diapers. Nothing says haute couture like a chicken walking around the living room in pink floral undies. Just don't convince yourself that you're reducing the infectious disease risk for other animals and people in the house. Better yet, let the chickens be chickens and keep them in a proper coop outside. I've seen too many indoor goats, pigs, miniature horses and other species with profound health problems from owners thinking they're just like people.
Apart from diapers, the store also sells "saddles" for the chickens. I'm not even going to start on that one.
I’ve received a lot of emails over the past 24 hours about the recent report of equine herpesvirus type 1 (EHV-1) neurological disease in an Ontario horse. The two main questions are whether there’s an outbreak and whether horse owners in Ontario should be concerned.
I don’t have any firsthand knowledge about this case (or any information beyond what’s been written elsewhere), but as far as I know, this is just a single sporadic case. That doesn’t mean an outbreak can’t occur, but most often, these just occur singly.
Whether there’s cause for concern is a tough question to answer. Yes, EHV-1 can be a serious problem, causing neurological disease in adult horses, abortion in pregnant mares, and severe disease in neonatal foals. Yet, at the same time, it’s an endemic disease that most often occurs as sporadic cases rather than large outbreaks (people just don’t hear about single cases as often, although they are now reported a lot more than they were a few years ago). The EHV-1 virus is very common and can be found in its dormant form in a large percentage of horses, so it’s not like some pathogens with which an unexposed population can suddenly be threatened when a single case is identified. In general I pay close attention to EHV-1 cases, but they are not a cause for panic. If a case occurs, we need to see if some broader issue is at play, and put steps in place to limit the problem, but we don’t need to cause massive disruption. In short, we want to ensure that good surveillance and infection control measures are in place, but not freak out in the process.
People have really taken a 180 degree turn in how they handle EHV-1 over the past 10 years or so. I don’t think we see EHV-1 neurological disease any more than when I was a resident. Back then, we saw sporadic cases and the odd small cluster, and people didn’t get too worked up about it in terms of the risk of transmission. Outbreaks, such as one I can remember associated with a large Ontario Standardbred yearling sale, certainly got lots of attention, but it was short-lived. Things changed (for good reason) based on some large, high-profile outbreaks in the last decade. It’s not known why such outbreaks now seem to be more common.
Anyway, if you live in Ontario and have a horse, don’t panic. Your horse is probably at no greater risk today than it was last month, assuming it wasn't in contact with the affected horse (which was diagnosed in early April). Virtually every horse is at some degree of EHV risk every day, but the odds of disease occurring are very low.
Some key prevention tips include:
- Use good general infection control practices to reduce exposure of horses to pathogens brought in by newly arrived horses.
- Observe your horses regularly and if there are any problems, isolate the horse and have a veterinarian examine it ASAP.
- When travelling to shows, races or other events, take measures to reduce direct and indirect contact between horses.
This is an increasingly common question, because MRSP is increasingly common. I've had two calls about it this week, and it's only Wednesday.
It's a good question to ask because MRSP (methicillin-resistant Staphylococcus pseudintermedius) is a highly drug-resistant bacterium that causes a lot of problems in dogs, and because of the high profile of its relatively distant relative, MRSA (methicillin-resistant Staphylococcus aureus), in people.
The short answer is: Yes, MRSP can infect people
BUT... (and it's a big and important but):
It's exceedingly rare and the overall risk is very low.
Here's my reasoning behind this answer:
1) Reports of MRSP infections in people are very rare.
- I think there are only two such published reports at the moment. There have probably been more infections than the number that are published, and there's the potential for MRSP to be misdiagnosed by some human diagnostic labs (meaning some MRSP infections may be mistaken for something else), but I think it's fair to sayl this a very rare infection in humans.
2) MRSP is not well adapted to infect people.
- MRSP is not inherently any more likely to cause infection than methicillin-susceptible strains of S. pseudintermedius (MSSP).
- MSSP can be found on basically every dog.
- A large percentage of the human population has contact with dogs every day.
- So, a large percentage of people encounter MSSP every day. Yet, reports of MSSP infection in people are very rare. To me, that indicates that this bacterium is poorly adapted to be a human pathogen.
3) Veterinary dermatologists are not extinct.
- MRSP is very common in dogs with skin infections. In some practices, it's the main cause of these infections.
- That means veterinary dermatologists encounter a lot of MRSP every day.
- I have yet to hear a report of a veterinary dermatologist getting an MRSP infection (carriers yes, disease no). I wouldn't be surprised if there actually have been some infections, but dermatologists can be considered the canaries in the mine when it comes to human MRSP risk, and I'm not aware of any real issues.
4) All dogs are biohazardous
- While this may not comfort the people calling me who are worried about the health of their families, it's important to put things into perspective. All dogs are carrying multiple microorganisms that could cause disease in people under the right circumstances (and the same goes for all cats, horses, people etc. for that matter).
- If you screened the average dog, you'd find things that are of greater concern that MRSP. In fact, MRSP probably barely cracks my "Top 10 List" of things I'm worried about the average dog spreading.
So, yes, there's a risk of MRSP infection when a person has contact with a dog infected with or carrying MRSP. There's also a risk of infection from methicillin-susceptible S. pseudintermedius, the version of the bug that basically all dogs carry, and a whole range of other bugs.
There will never be a zero-risk pet when it comes to zoonotic diseases. It's impossible. The risks may be very low but we can never eliminate all risk, just like we can never eliminate all risk from walking down the street. For some people, that slight degree of uncontrollable risk might be too much to handle, and they probably shouldn't own a pet. For most, the positive aspects of pet ownership outweigh the risks, and some basic hygiene practices (e.g. handwashing, avoiding licking, avoiding contact with the dog's mouth, nose and bum) can reduce that already low risk even further.
While this morning's -7C temperature and snow don't exactly make me think about sandboxes or wandering around barefoot, warmer weather will presumably occur someday and the risk of outdoor exposure to parasites will start up again.
Since nothing says summer like hookworms, here's a new info sheet all about hookworms, including information on cutaneous larva migrans. The sheet can also be found on the Worms & Germs Resources - Pets page, along with info sheets on many other topics.
Business Mirror, a Philippine news website, had a recent article entitled "Rabies: deadlier than ever". That's a bit like saying Decapitation: now an even worse idea. Rabies isn't 'deadlier than ever,' since it's hard to get deadlier when the disease is already almost invariably fatal.
Anyway, beyond quibbling about the title, there are some interesting parts to the tragic story.
The article describes the death of a young boy. He was attacked by a dog while playing in his front yard in the Philippines. After the attack, he was taken to the hospital where, while he treated for some large scratches, he was not treated for rabies exposure because there were no bites.
This isn't too surprising, since it's an area in which there are some education gaps and misconceptions. The main risk for rabies transmission from dogs is from bites, since the virus is present in high levels in saliva, and bites directly inoculate saliva into the body. Rabies contaminated saliva deposited on intact skin isn't a risk. Rabies virus shouldn't be hanging out on a dogs paws, so it's easy to see how the transmission risk from scratches might be overlooked. However, during an attack, saliva contamination of the skin and a scratch that breaks the skin can both occur, thereby inoculating rabies virus into the body just like a bite.
Presumably that's what happened here, because 2 months after the attack, the boy developed rabies. It started with severe itchiness over the site of the scratch, and he was dead two days later.
We can't play around with rabies. If there's potential that an animal interaction led to rabies exposure:
- The animal must be identified and either euthanized so its brain can be tested, or (if a dog or cat) quarantined for 10 days to ensure that it does not exhibit any signs of rabies.
- If the animal can't be identified and quarantined or tested (or if it's positive for rabies), proper post-exposure treatment is required.
More information about rabies can be found on the Worms & Germs Resources - Pets page.
“Is MRSP zoonotic?” That’s a question I get all the time. MRSP (methicillin-resistant Staphylococcus pseudintermedius) is a canine staph (a bacterium) to which people are exposed all the time. Yes, it can infect people, but only very rarely, particularly when you consider how often they’re exposed. Nonetheless, human MRSP infections can occur.
My typical answer to the question is “Yes, but…” followed by an explanation of the overall low risk. My general line is:
- It can be transmitted to people.
- Human infections are very rare
- There’s no use panicking over MRSP or being draconian when you have an infected animal.
- At the same time, no one wants a highly resistant infection, so some basic measures should be used to reduce the risk of transmission.
Issues are also greater when people with compromised immune systems are involved, and a recent paper highlights this.
The paper (Savini et al, Journal of Clinical Microbiology 2013) describes MRSP infection in a 65-year-old man who was immunocompromised because of a bone marrow transplant. He developed a wound infection, and his physicians and the diagnostic lab did a pretty comprehensive study of the bacterium they isolated from the wound, ultimately determining it to be MRSP.
The man lived “close to a pet dog and farm cows," whatever that means. The dog was probably the source, but unfortunately (as is common) no efforts were made to see if the dog was carrying MRSP, to see if the cows were positive for MRSP (since this bug can rarely be found in cattle), or to type the isolate to see how it compares to strains that are typically found in animals.
Will this report change my answer to the first question? No. It gives me another example of a human MRSP infection, but such events are still exceedingly rare and this individual was highly immunocompromised, having graft-vs-host disease after his bone marrow transplant.
We don’t need to be afraid of MRSP, but we need to realize there is some risk, and the risk is presumably higher for certain people (e.g. very young, very old, people with compromised immune systems). We therefore need to use some basic infection control and hygiene practices to reduce the incidence of transmission of MRSP and other potentially harmful microorganisms from animals to people.
More information about MRSP can be found on the Worms & Germs Resources - Pets page.
Allegedly, spring is here. The foot of snow on the ground and minus double-digit temperatures don’t really convince me, but the calendar can't lie, I guess.
Anyway, spring brings with it many things, one of which is hatching chicks. I saw signs for them at a local farm supply store a couple of days ago, and perhaps not coincidentally, this week’s edition of CDC’s Morbidity and Mortality Weekly Reports provides an update on the 2012 human Salmonella outbreak that was linked to contact with chicks and ducklings from a single supplier.
This outbreak has been talked about before, but this report gives some final numbers.
- Ultimately, 195 people infected with the outbreak strain of Salmonella Infantis were identified. (That’s probably a major underestimation too, since in outbreaks like this lots of people get sick but don’t have fecal cultures for Salmonella performed.)
- 33% of affected individuals were children 10 years of age or less.
- 79% of people who got sick reported contact with poultry in the week before illness started.
- Birds were obtained from various feed stores or directly from hatcheries, and 87% of people that provided information about chick or duckling sources reported getting them from a single mail-order hatchery in Ohio.
Chicks and Salmonella go hand-in-hard. Chicks are high-risk for shedding the bacterium, and people can get infected by handling chicks or having contact with their environment. Children are at high risk for infection since they tend to have closer contact with chicks and because they are more susceptible to Salmonella. That’s why it’s recommended that kids less than 5 years of age not have contact with young poultry. Day cares and kindergartens planning on their annual hatching chick programs… please take note.
The article includes some more recommendations.
- Feed stores should use physical barriers (e.g., a wall or fence) between customers and poultry displays to prevent direct contact with poultry.
- Educational materials warning customers of and advising them on how to reduce the risk for Salmonella infection from live poultry should be distributed with all live poultry purchases
Part of the last point is keeping young kids away from chicks and stressing good hand hygiene practices. Like most things in infection control, a little common sense goes a long way.
I write a lot about reptiles, and while it's usually in the context of their biohazardous nature, I actually like them. I've owned some before and it's not outside of the realm of possibility that we'll get more in the future (I might be safe with that statement since Heather doesn't read this blog. However, her co-workers that do will likely rat me out).
Reptiles can be good pets in some situations. The key is understanding and accepting the risk. That involves understanding the risks associated with reptiles, understanding the types of households where the risk is high, and knowing what to do to reduce the risk.
Denial isn't an effective infection control measure.
- Uh...no. Reptiles are clearly higher risk when it comes to Salmonella. Reptile contact has been clearly and repeatedly shown to be a risk factor for human salmonellosis. Dogs and cats (and various other animals) are potential sources of salmonellosis, but while many more people have contact with dogs and cats, reptile contact is much more likely to result in Salmonella transmission. It only makes sense. Reptiles are at very high risk for shedding the bacterium. Dogs and cats rarely do (especially when they're not fed raw meat).
"She’s never seen a case in the 30-plus years she’s been working with reptiles."
- Ok. So, since I've never actually seen influenza virus, I'll never get the flu?
- I know a lot of infectious disease physicians who have had a very different experience. In fact, it's rare for me to talk to an infectious diseases physician without him/her providing details of various reptile-associated salmonellosis cases.
Talking about the risk of Salmonella shouldn't be taken as insulting or a threat to reptile enthusiasts. People should accept that the risk is present and try to minimize it. The article actually has some useful information along those line. "Just use common sense - wash hands thoroughly after handling the animal or its cage. A good rule of thumb is to keep hand sanitizer nearby. While children under age 5 should avoid any contact with reptiles, Hart doesn’t advise snakes for children under age 7 or 8 for fear they could unwittingly harm the creature."
Reducing the risk is common sense. Keep reptiles out of high risk environments and use basic hygiene and infection control practices.
However, any semblance of common sense goes out the door when a rescue like this offers programs where you can pay them to bring reptiles to daycares, pre-schools and grade schools. So much for young kids avoiding contact with reptiles.
Reptiles aren't bad, they're just bad in certain situations. Common sense needs to be more common.
I tend not to write about recalls but the recent, large and expanding pet treat recall has lead to a lot of questions that are worth discussing. At last report, treats manufactured by Kasel Associates Industries Inc from April 20-Sept 19, 2012 were potentially contaminated with Salmonella and recalled. Not surprisingly, most of the recalled treats are things like pig ears, bully sticks and jerky strips made from raw animal products. The impact on pets isn't clear beyond a vague statement about "a small number of complaints of illness in dogs who were exposed to the treats." Anyway, here are some common questions I've been hearing:
My dog ate a recalled treat, will it get sick? Maybe, but probably not. It's not clear how many treats were really contaminated, so it's quite possible that most products weren't contaminated. Furthermore, the dose of Salmonella that a dog ingests is important. Low-level contamination is less of a concern, particularly in otherwise healthy dogs. The strain of Salmonella itself also plays a role since some strains seem to cause more serious disease or cause disease at lower doses than others. I haven't seen much information about the strain (or strains) involved here.
If my dog gets sick, what will happen? That's highly variable. Salmonella can cause disease ranging from vague (e.g. a little depressed and decreased appetite) to classical intestinal disease (e.g. diarrhea +/- vomiting) to rare but severe systemic disease (e.g. sudden death, bloodstream infection with subsequent overwhelming body-wide infection or focal infection of different body sites like joints).
Should my dog be tested for Salmonella? Not if it's healthy. The main question is what would be done with the result. If positive, it wouldn't mean that anything needs to be done or even that disease is likely to occur. A negative isn't very helpful either since a single sample is far from 100% sensitive. The key point is that we treat disease, not culture results. If the dog looks healthy, it's not going to be treated, regardless of the culture result. You'd also need to have the isolate tested to see if it's the same as the strain in the recalled treats if you wanted to determine whether treats were the source, and that testing is not readily available.
Should my dog be treated with antibiotics? As you can guess from the paragraph above - no. There's no evidence that antibiotic treatment of an exposed dog or a healthy carrier reduces the risk of disease or shortens the shedding time. In fact, it might even make things worse by disrupting the normal protective intestinal bacterial population, which might make disease more likely or make it harder for the body to eliminate Salmonella. Treatment might also encourage development of antibiotic resistance, something we don't need any more of with Salmonella.
What can I do to reduce the risk of disease? Not much. If a dog has eaten a Salmonella-contaminated treat, there's not really anything that can be done after the fact beyond watching for signs of disease.
So... what should I do? Relax and watch. The odds of a problem are low. If a problem develops, odds are it will be mild. That's not to say that severe disease can't or won't happen, it's just that it's unlikely and there's nothing that you can do after exposure anyway. Identifying signs consistent with early disease (e.g. lethargy, decreased appetite, diarrhea) and getting prompt veterinary care should help reduce the risk of complications or serious disease.
I'm just back from vacation (luckily, with no infectious disease stories to write), but now I have to catch up on a few posts. One easy one that was waiting for me in my inbox was about Salmonella and hedgehogs.
I've written before about biohazardous hedgehogs, and more details about the US 2011-2013 multi-state Salmonella outbreak were reported in a recent edition of CDC's Morbidity and Mortality Weekly Reports. The outbreak was identified through recognition of a cluster of infections in people caused by the same, historically rare strain of Salmonella Typhimurium. Finding a cluster of the same strain, especially a rare one, suggests that there might be a common source, so an investigation ensued. Here are some highlights:
- Twenty people from 8 states (Alabama, Illinois, Indiana, Michigan, Minnesota, Ohio, Oregon and Washington) were affected, although (as is typical) it's almost guaranteed that many more people were affected but not tested.
- Young people were more often affected, with the average age being 13. The age range spanned from less than 1 year to 91 years of age.
- Four people were hospitalized and one died.
- 14/15 (93%) people interviewed reported direct or indirect contact with a hedgehog. That's a pretty strong indication that hedgehogs might be involved, since that number is wildly disproportionate to the percentage of people in the general population that have contact with hedgehogs.
- Hedgehogs were obtained from various breeders, not from a single source.That's not uncommon since breeders often get animals from other breeders or suppliers and a point-source of infection further up the supply chain is likely.
For some reason, hedgehogs are high risk pets when it comes to Salmonella. High Salmonella shedding rates have been identified in studies of healthy hedgehogs and it's clear that contact with healthy carriers can lead to human infection. Hedgehogs should be considered alongside reptiles in terms of pets that should not be present in high risk households (households with kids less than 5 years of age, elderly individuals, pregnant women or people with compromised immune systems). Hedgehog owners should take care to avoid direct and indirect contact with feces and use good hygiene practices to reduce the risk of infection.
It's been quite a while since the last post about MRSA in horses, but rest assured, it's still out there! Not too surprisingly it's also spreading (or at least starting to be found) in new places. A recent report in Veterinary Microbiology (Schwaber et al, 2013) describes an MRSA outbreak at a large animal teaching hospital in Israel. It is the first report of MRSA colonization in horses in the Middle East, although it's possible (and quite likely) that there's more to be found.
The discovery of the problem had a pretty typical progression: there were two horses in the hospital with post-operative wound infections from which Staphylococcus aureus was cultured, and the isolates from both horses had similar antimicrobial resistance patterns, including resistance to all beta-lactam antimicrobials (= MRSA). Validly concerned about the potential for the MRSA to spread among horses and people in the hospital, an investigation ensued - in this case the National Center for Infection Control (NCIC) was actually called in to coordinate the operation.
- They found MRSA in 12/84 (14.3%) horses, of which 11 were in the hospital at the time of sampling, and 1 had recently been discharged from the hospital. Consider though that 44 of the horses sampled were simply from farms from which an MRSA-positive horse had come - so 11/40 horses in the hospital were positive - that's 27.5%!
- 16/139 (11.5%) of personnel at the teaching hospital were positive for MRSA. Fortunately there were no clinical MRSA infections reported in people.
- The MRSA strain that was found in all the horses and most of the people was a very rare type - not the usual sequence type 8 (ST8) we're used to finding in horses in various other parts of the world. This one was an ST5, spa-type t535, SCCmec type V, which is even rare in the human population.
- The primary action taken to get the outbreak under control: increased infection control measures, including isolation of infected and colonized horses which were then handled with contact precautions (e.g. gloves, gowns), discharging horses from hospital as soon as medically possible to decrease transmission pressure, and having a nurse from the NCIC come in to instruct personnel on the measures to be taken, including emphasis on hand hygiene and increased use of alcohol-based hand sanitizer.
- In this outbreak, decolonization therapy was prescribed for all colonized personnel.
The report does not mention whether or not personnel at the hospital were required to submit to being tested and undergoing decolonization therapy. This can be a very tricky issue to handle, and it depends on what the local laws are. In Canada, employees cannot be forced to undergo testing or treatment, but in some other countries MRSA-positive healthcare workers may not be allowed to even work until their carrier status is cleared.
Interestingly enough, just a year or two before this outbreak occurred a study (as yet unpublished) had been carried out in the same region, during which they found MRSA in 7.2% (6/83) of hospitalized horses and none in horses from local farms. There is no mention regarding whether or not the hospital had taken measures to eradicate MRSA from the facility before the clinical infections that triggered the outbreak investigation occurred.
This was a typical MRSA "iceberg" - a couple of clinical cases were triggers for an investigation that found a lot more horses and people were actually carriers. This is exactly why it's important to remain diligent about infection control measures like hand hygiene at all times, so that pathogens like MRSA don't move in "under the radar." The authors of the paper summed it up nicely (although I'd leave out the part about decolonization):
"Strict implementation of hand hygiene, isolation of colonized and infected horses, decolonization
of colonized personnel and above all, constant education of veterinary students and personnel about the importance of infection control measures are required in order to decrease the risk for colonization and infection of both horses and personnel by MRSA and other pathogens."
More information about MRSA in horses is available on the Worms & Germs Resource - Horses page.
ProMed Mail's monthly US rabies update often contains some interesting cases, and the last one is no exception.
A llama in Georgia became aggressive, started biting itself and was spitting at one of its caretakers. A spitting llama certainly doesn't mean rabies (I have dodged enough llama spitballs to know that) but any sudden change in behaviour, especially with aggression, should raise some major red flags. Here, the llama was diagnosed as rabid and the person that was spat on is receiving post-exposure treatment.
A bobcat attacked a man and boy in Massachusetts, and not surprisingly, was diagnosed with rabies. In this case, the bobcat pounced on the man, bit his face, clawed his back and held him in something akin to a bear hug, before moving on to the man's nephew. Wild animals don't typically attack except under extenuating circumstances (e.g. being cornered, protecting offspring), so this type of event should be considered a rabies exposure until proven otherwise. The man shot the bobcat and it was confirmed as rabid.
In an all-too-common scenario, a family that took in a stray kitten ended up needing post-exposure treatment because the kitten was rabid. They found the sick kitten and tried to nurse it back to health, but it died the next day. Fortunately, animal control arranged for rabies testing, something that could have easily been overlooked if no one thought about rabies and just assumed the kitten was sick for some other reason. Two dogs in the household were also considered exposed, but fortunately had been properly vaccinated, so typical recommendations would be for a 45-day observation period versus 6 months strict quarantine or immediate euthanasia had they not been vaccinated.
In a similar scenario, two women are undergoing post-exposure treatment after being bitten by a stray kitten they were trying to catch. After they caught the kitten, they took it to a local Humane Society, where it was euthanized because of the bite. This ended up being an efficient approach, but more often there would be a 10 day observation period of an animal that had bitten someone, to see if it developed signs of rabies. If signs occurred the animal would be euthanized and tested for rabies, but if not then (theoretically) the animal would not have been shedding rabies virus at the time the bite occurred. Immediate euthanasia after a bite is not the typical recommendation, so I wonder whether the kitten was already showing some signs of disease. Otherwise, it wasn't a textbook approach to bite management but it ultimately resulted in the right outcome.
These cases have a few recurring themes:
- Changes in animal behaviour should lead to consideration of rabies.
- Be wary of stray animals. It's best to stay away from them. If you end up taking in a stray, if it gets sick and dies, ensure that it is tested for rabies.
- Vaccinate your pets because you never know when you'll encounter rabies.
1) Do you know what a bully stick actually is?
2) Do you know what's in it?
A recent study headed up by Dr. Lisa Freeman, published in this month's Canadian Veterinary Journal (Freeman et al., CVJ 2013;54:50-54), looked into this by asking people what they thought bully sticks were made of, and testing the treats for calorie count and bacterial contamination.
The answer to question 1 is: bully sticks are raw, dried bull penis (which explains the need for a cuter name).
- Only 44% of people surveyed knew that.
Also, bull penis is considered a by-product, yet 71% of people that fed bully sticks to their dogs said they avoid by-products in food.
- This just shows a lack of understanding about what by-products are and their nutritional value. Many people classified things that are prohibited from by-products as being by-products, such as hooves, horns, road kill and euthanized pets. By-products aren't always bad and can, in fact, have good nutritional value. Also, they can be environmentally friendly and ethical since they are often made from nutritionally valuable parts of the animal that might otherwise be thrown out, thereby providing food for pets without taking anything out of the human food supply chain.
"What's in it?" was approached from 2 standpoints:
Firstly, caloric content was assessed.
- Treats often get ignored when thinking about a pet's caloric intake, but calorie-dense treats can certainly contribute to obesity. Fifty percent of people surveyed underestimated the calorie counts of bully sticks. The average caloric density was 3 calories/gram, and given the variation in size of bully sticks, total calorie counts for a single stick ranged from 45-133 calories (9-22 calories/inch). So, yes, size matters.
Secondly (my bit part in this study), we looked at contamination by a select group of bacteria.
- Salmonella wasn't found, which was encouraging since high Salmonella contamination rates have previously been found in some treats (mainly pig ears), and contact with pet treats has been implicated in some outbreaks of salmonellosis in people. We found Clostridium difficile in 1 treat (4% overall). That doesn't worry me too much since it's increasingly clear that we encounter this bacterium regularly. With common sense and handwashing, it's probably of little risk, but in some people (e.g. elderly, people on antibiotics, people with compromised immune systems) it might be more of a concern. We also found methicillin-resistant Staphylococcus aureus (MRSA) in one sample. This was a "livestock-associated" MRSA strain that can cause infections in people, but the risk is unclear. Theoretically, it's a potential source of exposure. If someone got MRSA on their hands from the treat then touched their nose (where MRSA likes to live) or a skin lesion (where it can cause an infection), then it could potentially cause a problem. Overall, the risk is probably quite low, but it's another reason to wash your hands after handling treats.
None of this means dog owners need to avoid bully sticks. It does mean that you should pay attention to what you feed your pet, think about treats when considering your pet's caloric intake (especially if your dog is overweight), keep treats away from high risk people (e.g. don't use a bully stick as a teething toy) and wash your hands after handling dog treats (of any kind).
Photo: A variety of bully sticks (also known as pizzle treats) often fed to dogs as chew treats (photo credit: Gergely Vaas 2006 (click for source))
The fact that Salmonella and reptiles go together is old news. I often get questions about testing reptiles to see if they are Salmonella carriers and I tell people not to bother since even with a negative result, I'd consider the animal to be positive. A recent study in the Journal of Zoo and Wildlife Medicine (Goupil et al 2012) provides more evidence for this.
This study involved testing 12 snakes used in a public educational program, by sampling them weekly for 10 weeks. Here are the highlights:
- 11/12 snakes were positive at least once.
- 58% of snakes were positive on 5 or more weeks.
- On a weekly basis, between 25-66% of snakes were positive.
- Fifteen (!) different types of Salmonella were identified. Nine snakes shed 2 or more different Salmonella types over the study period.
- Two samples from feeder rodents were also positive.
This shows nicely how a single negative sample doesn't guarantee that a snake is truly negative. It also shows how common Salmonella is in snakes. The positive cultures from the feeder mice aren't surprising either, but shows that even if a snake was truly Salmonella negative, it could be exposed at any time through its food, and that there is potential public health risk from contact with feeder mice (something that large international outbreaks of human infection from infected feeder mice have shown).
This study just reinforces some key concepts:
- Assume all snakes are Salmonella carriers.
- Use good hygiene practices around snakes and feeder rodents.
- Keep snakes away from high risk individuals (e.g. the very young, elderly, pregnant, immunocompromised).
- Don't waste your money testing your snake for Salmonella. Focus your efforts on smart and practical management practices.
More information about reptiles and Salmonella can be found on the Worms & Germs Resources - Pets page.
The 15 cm of snow that fell last night is as good of an indicator as any that agricultural fair season is over in this region. But, planning ahead is important (and often not done well with fair petting zoos), so it's never to early to make a plan for next season. Petting zoos can be fun and educational, but are also associated with infectious disease risk. There's always some inherent risk with any kind of animal contact, since all animals (and people) carry a multitude of infectious agents. However, understanding pathogen shedding patterns is useful to help determine the best control measures.
A recent study in Comparative Immunology, Microbiology and Infectious Diseases (Roug et al 2012) looked at shedding of selected pathogens by cattle, sheep, goats, pigs, poultry, rabbits and horses at a California county fair. Here are some of the highlights:
- E. coli O157 was found in one animal. This is the main outbreak concern when it comes to petting zoos, because very low numbers of bacteria are required to cause disease and human infections can be very severe. Surprisingly, the positive animal was a pig, not a ruminant, as would be typical.
- Salmonella was isolated from feces of 3 animals: 2 pigs and 1 chicken.
- Campylobacter jejuni, another potential cause of diarrhea in people, was found in 3 animals: 2 cattle and 1 sheep. The 2 positive cattle were adult dairy cattle and they represented 17% of all tested cattle. That's a surprisingly high rate for adult dairy cattle, in my experience.
- Other Campylobacter species were found in 2 cattle, 3 goats (30% of all goats tested) and 1 chicken.
- Antibiotic-resistant E. coli were common, particularly in pigs.
- The parasites Cryptosporidium and Giardia, and the bacterium Vibrio, were not found.
The study didn't look at other aspects of the petting zoo, such as the types of contacts that were allowed, but based on the pictures that were included with the paper, they weren't optimal. Given the results, the picture of two children in the pen with the pigs (including one child who was sitting on the ground leaning against a pig) should raise some concern.
Does this study change anything? Not really, but more information can't hurt. We know that petting zoo animals can carry pathogens, and we have to assume that every animal in a petting zoo is carrying something that could cause an infection given the "right" circumstances. That's why there's a focus on good general hygiene and infection control practices (especially hand hygiene), along with excluding animals that are at particularly high risk. As the authors say "The study findings should not be interpreted as a deterrent to visit agricultural fairs, but as a reminder that good hygiene and sanitation are critical in these settings."
Following up on my recent post about MRSP in rats, here’s a story about MRSA in an alpaca (Stull et al, Can Vet J 2012). As far as we know, it’s the first report of MRSA in an alpaca (or any camelid).
The report relates to our large animal hospital, where we perform MRSA screening of all horses at admission, weekly during hospitalization and at the time of discharge. It's all part of our infection control program, and the screening is designed to help reduce the risk to horses and our hospital personnel, since this multidrug-resistant bacterium is endemic in the Ontario (and broader) horse population, and outbreaks can occur in equine hospitals.
While alpaca’s aren’t horses, and we don’t see that many of them here, they sometimes get screened anyway since screening is being done on most of the other patients.
This case involved a neonatal alpaca that was admitted with its mother because of severe respiratory disease. The cria (baby alpaca) was very sick and was ultimately euthanized about 36 hours after admission.
Surprisingly, the admission MRSA sample from the cria was positive. In this case, MRSA wasn’t involved in the animal's illness. The cria didn’t have any evidence of bacterial infection, so this was an incidental (but interesting) finding.
When the bacterium was tested further, it was classified as CMRSA-5 (Canadian epidemic MRSA-5), a human strain that also predominates in horses in North America. The mother alpaca was MRSA negative. Presumably, the cria picked up MRSA from the farm environment or a person shortly after birth. MRSA (especially CMRSA-5) carriage rates are high amongst horse owners and horse vets compared to the general public, and it would have been nice to have determined if there were any horses on the alpaca’s home farm, but we couldn’t get any follow-up information.
This single case is probably of limited concern in the grand scheme of things. It’s likely an "oddball" infection rather than an indication that MRSA is a serious threat to alpacas, or that alpacas are a relevant source of human MRSA infection. However, that’s largely what was said when MRSA was first found in horses in the late 1990's and early 2000's, and it has since become a significant issue in that species, so the potential for MRSA to become a problem in alpacas can’t be completely dismissed.
If nothing else, the occurrence of this case is an indication of the need think broadly when it comes to infectious diseases, since many pathogens don’t have species boundaries. CMRSA-5 is a human-origin MRSA strain, but it’s worked its way outside of its natural host. It’s not the first and certainly won't be the last bug to make its way from people to animals.
This story's a couple of weeks old, but Sonoma County (California) residents have been warned about an outbreak of salmonellosis in songbirds. Outbreaks of salmonellosis occur occasionally in songbirds such as finches, and can result is lots of sick and dead birds. There are also risks to other species, including cats and people.
Why cats? Cats can be exposed to Salmonella from eating infected songbirds, and sick birds are typically a lot easier to catch than healthy ones.
Why people? People can be exposed to Salmonella from areas the birds have contaminated, particularly bird feeders and their vicinity. People have been advised to remove bird feeders or clean them regularly, and to promptly remove dead birds from under feeders.
- Removing bird feeders temporarily might help keep birds (including sick birds) farther away from people. It's not going to hurt the birds since other food supplies are typically abundant.
- Washing feeders can reduce the Salmonella burden but it could also increase the risk to people if they contaminate themselves while washing them. Certainly, people should not wash bird feeders inside the house, especially not in the kitchen sink. They should also take care to avoid contaminating their clothing and make sure they wash their hands thoroughly after finishing with the feeder.
"Songbird fever" is a colloquial name for salmonellosis in cats - a testament to the potential for feline infection. It's uncommon but can be severe, and cats can act as a bridge between sick birds and people by bringing Salmonella into the household. This is just one of many reasons why domestic cats are better off living indoors.
A year or two ago, I received an email from Dr. Chelsea Himsworth, who was doing some interesting work looking at different bacteria found in rats in Vancouver's Downtown Eastside. This is an impoverished urban neighbourhood with lots of homeless people, IV drug users and HIV-infected individuals... and lots of rats. Dr. Himsworth, a veterinary pathologist working on a PhD at the University of British Columbia, is assessing potential health risks posed by rats to this type of population. The reason she got ahold of me was to see if I was interested in looking for some different bacteria, like methicillin-resistant staphylococci, in these rodents.
If you look, you often find, and that was the case here with methicillin-resistant Staphylococcus pseudintermedius (MRSP). This multidrug resistant bacterium was found in nasal or oral swabs from 2.1% of rats (Himsworth et al, Emerging Infectious Diseases 2013). So it was relatively uncommon but certainly present.
One question: from where did it come? Most MRSP isolates found were the same as the most common strain found in dogs, so presumably the rats picked it up directly or indirectly from pets or stray dogs. However, there was also a type we've never run across before. That could mean that there is a separate rat-associated MRSP strain, but more likely it means this strain is present in dogs in Vancouver and we just haven't found in dogs elsewhere yet (there aren't many of us typing MRSP, and we find new strains not uncommonly). While dogs and rats presumably don't spend time lounging around together, there is certainly potential for direct or indirect contact between dogs and rats, and rats have been found to harbour dog-associated oral bacteria in the past.
Another question: what's the risk to people? The risk of infection is probably limited, but not zero. MRSP can cause infections in people but doesn't do so very often. MRSP is unfortunately becoming fairly common in dogs, so people are commonly exposed, yet human infections are still rarely diagnosed. So, the risk to humans from these rats carrying MRSP is pretty low overall, although we'd rather not see new reservoirs for this bug.
What about the rats? Rats may be the innocent bystander here, having been infected by dogs. We don't know whether MRSP causes infections in rats. It probably can in certain circumstances.
Can rats spread this to dogs? I guess it's possible. Rats are probably not contaminating the environment too heavily with this bug from their noses or mouths (compared to dogs), but direct transmission if a dog caught a carrier rat could certainly be possible. The risk to the dog population is pretty low since this pathogen is well established in dogs already and there's a lot more dog-dog than rat-dog contact.
Why does an antibiotic-resistant bacterium live in these rats when they're not receiving antibiotics? Good question. Antibiotics certainly help when it comes to selecting for resistant bacteria, but they're not absolutely required. There are a lot of other factors that can also play a role, so rats don't need direct or indirect exposure to antibiotics to acquire MRSP (or other multidrug-resistant bacteria). It could be that they are just commonly exposed and the bacterium only hangs around for a short period of time, or that there are some other factors in the rats, their food or their environment that select for these resistant bacteria.
About 500 people have sent me this article over the past week, so I guess I should get around to making some comments. The article entitled "Using a dog’s superior olfactory sensitivity to identify Clostridium difficile in stools and patients: proof of principle study" (Bomers et al 2012) is in the Christmas edition of BMJ, an edition in which they typically publish something fun or light. The study describes the use of a dog trained to sniff out C. difficile, an important cause of diarrhea people, especially hospital patients. The premise is that dogs could be used as a rapid and cheap way to diagnose C. difficile infection, and therefore allow for earlier treatment and implementation of enhanced infection control measures.
There were 3 components of the study:
1) Detection of C. difficile on a culture plate
The dog was trained using culture plates containing C. difficile. That's how they have to start, but detecting C. diff on a culture plates is pretty easy. I can do that, and my nose is nowhere near as good as a dog's. Clostridium difficile has a very characteristic odour on a culture plate and odour is one of the methods that's commonly used to determine whether C. difficile might be present on the plate.
2) Detection of C. difficile in stool
For this, the researchers set the bar pretty low. A positive fecal sample was considered one that was culture-positive positive on a test to detect the C. diff toxins. We know toxin tests are pretty insensitive (they give a lot of false-negatives), which is why there's a major movement to replace them with molecular tests. By requiring the sample be positive on both culture and toxin test, it means that the samples had to have been quite positive to be considered (i.e. they didn't test the dog with "weaker" positive samples that may have had less C. diff and C. diff toxin in them). That weakens the results a bit, but they're still interesting.
They presented the dog with 50 positive and 50 negative samples. The dog gave a positive response to all 50 positive and a negative response to 47/50 negative samples.
3) Detection of C. difficile in patients
Here's where it gets more interesting and potentially more relevant, since the real value in a sniffer dog would be to detect C. diff directly from patients, as a rapid and cheap screening tool.
For this part, they enrolled 30 patients with C. difficile infection and 270 controls. One problem I have is that 94% of their controls were non-diarrheic. It raises questions about whether the dog is detecting C. difficile or just diarrhea, since the groups don't just differ by their C. diff status, as would be most appropriate for a control group. The more differences there are between the groups, the greater the potential that a difference other than the one of interest (i.e. C. diff status) is actually the thing that's being detected. There' a big difference between a dog that can detect C. difficile and a dog that just detects diarrhea.
Another issue is that some C. difficile strains don't produce toxins and are not able to cause disease, but they'd presumably be detected the in the same way based on odour, in contrast to tests that are based on detection of the bacterial toxin or genes that encode toxin production.
Anyway, the dog correctly identified 25/30 (83%) cases and 265 (98%) controls. Not as good as current molecular tests but pretty remarkable, nonetheless.
Overall, it's an interesting story and shows how good a dog's nose can be, how smart (some) dogs are, and how thinking outside the box can result in some interesting ideas. Though I don't think diagnostic testing companies have much to worry about at this time in terms of competition from sniffer dogs.
Cool concept. Fun paper. Not coming to a hospital near you in the near future, but not something to completely dismiss.
Doug Powell, renowned for his food safety efforts and Barfblog, often uses the phrase "don’t eat poop" when it comes to food safety. I’ve stolen that line and I now use it a lot too when talking about zoonotic disease. However, over time, I’ve started to wonder whether the line always applies.
I was giving a talk last week and the question of "how clean is too clean?" came up. It’s not the first time, and I have a tough time answering it these days. The response relates to a few things, such as the hugely important role of our commensal bacterial population and the "hygiene hypothesis."
While some people might be turned off by the concept, we are outnumbered by bacteria in our own bodies. We have approximately 10 bacterial cells in or on us for every one of our own cells. When you compare the number of bacterial genes to our genes, the difference gets even bigger. While bacteria can cause disease, they are also critical to our health - we actually can’t live without them. They help our immune system develop and function. They help with digestion. The help us fight off other more harmful microorganisms. They produce vitamins and other compounds. They interact with us in ways that we don’t full understand, and probably in ways we’ve never even thought about. We know clearly the intestinal bacterial population plays a role in things like allergic diseases, and there’s increasing evidence of interaction between our intestinal bacteria and our brain.
A key part of our development is learning to how to live with and tolerate our bacterial microbiota. If our bodies recognized all bacteria as bad foreign invaders, we’d kill ourselves trying to kill them. Instead, we develop tolerance to certain bacterial populations. Developing tolerance is a critical aspect of healthy life, and things that interfere with development of tolerance might set the scene for future diseases, particularly allergic and inflammatory diseases. That’s where the hygiene hypothesis comes in: are we now too clean?
So, the concept that all bugs are bad is clearly wrong. Which bugs are good and how to live with the abundant microbial world in and around us is the tougher question to answer. Previous approaches to infectious diseases, based on "find bacterium… must kill…", are too simplistic and potential harmful in some situations. There’s new research indicating that the best treatment for recurrent Clostridium difficile infection may be administration of feces from a healthy donor by enema. So, clearly exposure to feces is not always bad.
Back to the original question (I was killing time on a plane as I wrote this so I had a chance to ramble on….): How clean to we want things to be, and can we be too clean? Furthermore, does reduction in our exposure to microorganisms predispose us to various diseases, such as allergic and inflammatory diseases? The answer to both of theseis presumably yes. However, what level of clean is good and what level is excessive?
In a hospital, we want clean... very clean. We have a highly susceptible population and lots of bad bugs in circulation. We want close attention paid to disinfection and thorough hand hygiene in hospitals, no doubt about it. But what about in the general population? Antibacterial soaps are not generally recommended for households because there’s no evidence they are needed and they might increase the likelihood of antibiotic resistance (since bacteria that become resistant to antibacterial agents in soaps can also be resistant to some antibiotics). We don’t need high level disinfection as a routine practice all over the house. At certain times and in certain areas, sure, it's certainly still a good idea. For example, if you’re working with raw chicken, careful attention to hygiene and surface disinfection is important because of the high likelihood of exposure to some important pathogens (e.g. Salmonella). But do we need to be spraying disinfectants around the rest of the house on a routine basis (as some TV commercials indicate)? Probably not.
Being a germaphobe can be good, but maybe it can also be bad. We need to think about the role of this complex and massive (yet still poorly defined) microbial population that lives with us. How much exposure to bacteria from different sources is actually needed for health, especially in kids? How much is harmful? There has to be a middle ground, and hopefully we’ll find it.
I’m not trying to say never wash your hands, just like I’d never say wash your hands after you touch anything, anytime. In certain locations (e.g. hospitals, food preparation areas) we need to pay extra attention to hygiene and disinfection. But what about the rest of the time? How do we find that balance? No one knows, but it’s an important question to consider.
Public health personnel in Chapin, Connecticut (USA) are trying to find a woman bitten by a rabid cat. The woman was driving down South Brear Hill Road when she came across a cat. She picked the cat up from the road and told someone else who was there that the cat bit her. She then drove away, and the cat was subsequently identified as being rabid. Now a search is underway to find the woman so she can be given post-exposure treatment.
This is clearly a high risk situation. As opposed to other public health alerts that try to find people who were in contact with a rabid animal on the off chance that they were bitten or otherwise exposed to the virus, this person was bitten and that creates a very high risk of rabies transmission.
The outcome is simple.
- If she gets rabies, she will almost certainly die.
- If she was exposed but gets post-exposure treatment soon (and completes the recommended course), she will almost certainly live.
It's easy to see how this could happen. The woman probably found the cat looking injured or lost on the road, and wanted to help. However, that action, and failure to recognize the risk associated with the bite, have put her life at risk.
A few general rabies reminders:
- Avoid contact with wildlife or any animals you don't know, especially if they seem sick or otherwise abnormal.
- If you are bitten, make sure the potential for rabies exposure is considered. The animal needs to be observed to see if it is rabid, or it needs to be tested. If the animal can't be monitored or tested, you can't rule out rabies and getting post-exposure treatment is the safest course of action.
More information about rabies can be found on the Worms & Germs Resources - Pets page.
I received an email from a relative the other day with a pet question. I get lots of these, but the surprising part is this relative doesn't have any pets (and I think is generally of the opinion that pets are okay, as long as they're not hers). She was asking about turtles. As a responsible prospective pet owner should, she was looking into the issues pertaining to the pet before getting the pet. I think she was more focused on general aspects of care and management, but zoonotic disease risks play into the equation too. This one was a no-brainer, since they have a young child in the house and reptiles shouldn't be present in households with children less than five years of age. So, problem averted, and the need to make a decision later about removing an inappropriate pet from a household was also avoided (along with the awkward "oh, you got a turtle?" Christmas dinner conversation).
But, what happens when people aren't so proactive? Turtles are often passed from house to house as people get bored with them, as they outgrow small aquariums or as parents of young or otherwise high-risk children tune into the Salmonella risks or owning such a pet. If you don't have a friend willing to take your turtle, what do you do?
Petco, a pet products company in the US, has launched a "turtle relinquishment program," whereby they take in "wayward" or unwanted turtles. As of a few weeks ago, 111 people from 10 US states had surrendered their turtles to Petco. The turtles are sent to a turtle farm in Louisiana.
So, this is an option for individuals (at least in the US) with no local way to rehome their turtle. The fact that the turtles are going somewhere to make more turtles (and more Salmonella) is a bit of a concern, but I can see the greater good. Staff at the farm say that turtles are treated for any signs of Salmonella when they arrive. This is a bit strange, since turtles don't typically develop disease from this bacterium - they simply shed it with no signs. Hopefully that doesn't mean the farm is just treating all the animals. It's basically impossible to eradicate Salmonella from turtles, so if they are routinely treating, they're probably breeding drug-resistant Salmonella along with baby turtles.
I know the typical round of emails is going to follow, from reptile advocates who have pretty much done everything except burn me in effigy (or in real life, fortunately). As I've said before, reptiles can make great pets, just not in all households. I've owned various reptiles myself, but reptiles and small kids don't go together. Too many kids get sick every year from pets like turtles. A small number die. That's just unacceptable.
More information about turtles and Salmonella can be found on the Worms & Germs Resources - Pets page.
Life with Merlin has been busy but going pretty well. There's been no pee on the floor in the past 48 hours so we're making progress. Speaking of pee (which, sadly, I seem to do a lot), we need to decide about leptospirosis vaccination for Merlin.
A good preventive medicine program is important for every pet. There's no "one size fits all" version - the program needs to be tailored for every region and pet/owner combination. We have Merlin's deworming covered. I gave him a booster vaccine the other day, which covers distemper, parvo and a couple of respiratory viruses (adenovirus type 2 and parainfluenza). Rabies vaccination will be coming soon, when he's a bit older (at least 3 months). Now that we have the "core" components covered, we need to think about the elective aspects. One of those is vaccination against leptospirosis.
When thinking about vaccination, it's a cost-benefit decision. The costs and benefits can be hard to accurately assess, but a few basic questions are key: Is there a risk of exposure? Is the disease of concern? Is there a safe and effective vaccine?
Is there a risk of exposure?
Leptospirosis, a potentially life-threatening infection caused by different types of Leptospira bacteria, has been called a "re-emerging" disease in many parts of North America since rates of infection have increased over the last 20 or so years.
Leptospirosis certainly occurs in dogs around here. We don't see a lot of cases but it's far from rare and it can be nasty.
Wildlife are the main reservoir. Infected wildlife shed the bacterium in their urine, and urine-contaminated water and wet areas are the main sources of infection. Raccoons are the biggest concern around here, and there is certainly no shortage of raccoons around my house (including in the garage sometimes). Since Merlin is a Labrador, he's bound to spend a lot of time swimming in ponds and wallowing around in wet areas on our property... prime sites to be contaminated by pee from infected wildlife. So, there's a reasonable chance that he'll be exposed.
Is the disease of concern?
There's no doubt here. While it's uncommon, it can be nasty. Life-threatening infections can occur and kidney failure is a major problem. Treatment of lepto can be difficult and expensive.
Is there a safe and effective vaccine?
Lepto vaccines have had a bad rap. Older vaccines weren't very effective (often not protecting against the strains that are of concern) and were associated with a high rate of adverse reactions. Those former concerns have persisted in some people despite the fact that there's a new generation of vaccines that are much more effective and safer. The new vaccines are better designed, better tested and cover a broader range of strains. There's quality research indicating that they work. Like any vaccine, they're not 100% effective but they are quite good overall.
Information about adverse reactions is harder to get. Adverse event reporting is sporadic at best, but the available information doesn't indicate that these vaccines cause a greater incidence of adverse reactions than any other vaccine. Any given vaccine can cause a problem in any given dog, but the overall risk is low.
So, don't tell Merlin but another set of vaccines is in his future.
The new puppy, now named Merlin, is keeping things busy around here. (Note to self: avoid getting a new puppy during miserable weather. Standing in pouring, driving rain at 4 AM is not fun. Okay, enough whining.)
Yesterday, I wrote about the new puppy's deworming plan. One thing I forgot to mention was the rest of the "herd." By that, I mean Meg, our 11-year-old Lab. Herd health gets a lot of attention in food animals and to a lesser degree in horses, but many concepts remain important for pets. Specifically, when you introduce a new member into the herd, you might change disease risks or required preventive measures for other members of the herd.
Meg lives a pretty cat-like existence. She sleeps, eats, walks far enough to go outside to pee and, well, that's about it. As an older dog who has very rare contact with other dogs, her risk of exposure to many microorganisms, such as parasites, is limited. However, since we brought a new little furry vector into the house, Meg might be exposed to some things that haven't been much of a concern in the past. Her habit of eating whatever she can find (including poop), increases that risk further. So, what's the herd health plan?
It's not too detailed, actually.
- One thing is making sure that we deworm Meg and we don't just focus on the puppy. She might be exposed to anything the puppy is/was shedding. We're usually pretty lax on deworming her in the winter months, but she'll get a couple of doses of dewormer alongside the puppy.
- Poop removal. Since Meg's a notorious poop-eater, we'll want to remove Merlin's waste promptly. That's pretty straightforward. If she can't find it, she can't eat it. It's also important to make sure that old feces aren't left around, because some parasites require time in the environment to become infectious, so regular feces removal prevents accumulation of infective forms of some. The current temperature is at the lower limit of where Toxocara eggs are able to develop into infectious larvae, and the risk will probably be pretty minimal as the temperature drops over the next few days, but it's not hard to make sure the yard gets cleaned up.
- If we find something in the puppy, then we'll have to consider whether Meg might be exposed or at risk too, and decide whether she needs to be tested or treated.
The other aspect of the herd is the non-canine component of the household (i.e. the kids). The key points for that, in terms of zoonotic parasites, are cleaning up feces from the yard, avoiding fecal contact, hand washing, treating the dogs appropriately to reduce parasite shedding and other basic feces-avoidance measures.
Hide the kids’ toys, tune up the carpet cleaner, get ready for some sleep deprivation… there’s a new dog in the house. Last night, the yet-to-be-named ("he who shall not be named" having been rejected by Heather) little yellow critter arrived. Meg (the existing dog) seems relatively content, or at least resigned. The cat... not so much, but he's already established who's the boss.
So, while I'm momentarily not trying to convince the puppy to pee outside, I’ll take this opportunity to hopefully practice what I preach and describe what we’re doing for things like vaccination, deworming and other infectious disease-related topics.
To start things off: What’s the deworming plan?
- Roundworms (Toxocara canis) are the main concern in puppies. It’s generally a good idea to assume that a young puppy has roundworms, regardless of from where it came and how well cared for it was.
- Canadian parasite treatment guidelines are to treat puppies with a drug that will kill Toxocara worms at 2, 4, 6 and 8 weeks of age, then monthly until 6 months of age. Our little guy is 9 weeks old and has already been treated a couple of times for roundworms, plus he's had one treatment for coccidia (a different parasite that was found on a recent fecal exam). He’ll get another dose of pyrantel pamoate in the next day or two, then monthly until he’s 6 months old. (If someone gets a puppy and it hasn’t been treated like this or its vaccination history isn’t known, it is recommended to give 3 treatments 2 weeks apart, then monthly until 6 months).
- A fecal exam will be done on the puppy in the near future. It’s not an emergency since it won’t impact what I do at the moment in terms of treatment, but it’s good to see if there are any parasites that aren’t killed by the chosen dewormer (e.g. tapeworms) and to detect resistant parasites (i.e. Toxocara eggs still found in feces after appropriate treatment).
- No flea treatment now since he doesn’t have any evidence of a flea infestation and it’s not very likely he’ll be exposed to fleas before the spring based on the current climate where we are.
- No heartworm treatment until the spring either. The Canadian Parasitology Expert Panel (CPEP) recommentaion is for dogs to receive monthly heartworm preventive treatments beginning at a maximum of two months of age. So, I’m not really following that one, but given the time of year, the low prevalence of heartworm in the area he's from and the fact that the puppy wouldn’t have had too much risk of mosquito exposure because of its age and indoor housing, the risk of heartworm exposure this season is very low.
More updates to come, and hopefully not too many descriptions of how to clean puppy feces off of various surfaces.
At the recent 9th International Conference on Equine Infectious Diseases (EIDC) in Lexington, Kentucky several sessions were focused on parasite control of horses. Drug resistant parasites are a world-wide problem in equine establishments, and it has become a challenge to define a simple and useful set of guidelines to be used by horse owners. As many readers of the Worms & Germs Blog will be aware, there is no longer a “one size fits all” program, and parasitologists instead often talk about the complexity related to the different parasites that often infect the horses in concert, their interactions with their hosts, and how to interpret fecal egg counts. While this is all useful and important information, it can be frustrating when it does not readily come with some practical guidance.
Equine parasitology is rarely well-represented at parasitology conferences. Usually, there are less than a handful equine abstracts, and often not even enough for a separate session. The three or so participating equine parasitologists often have to create their own little scientific session over a cup of coffee during the breaks. The EIDC was much different. It had participation from leading equine parasitologists from Sweden, Denmark, Finland, Germany, United Kingdom, Canada, Brazil, and the USA. More than 30 parasitology abstracts were presented at the meeting, and a special session critically addressed the most pressing research needs for equine parasite control. During the conference, an international equine parasitology consortium was formed, and it will serve to coordinate future research efforts and to communicate consensus-based guidelines for parasite control.
So, what are these recommendations then? New research presented at the EIDC illustrated very well that general recommendations are more straight-forward than often anticipated. Work performed by Kurt Pfister and colleagues in Germany illustrated that fecal egg counts are useful for monitoring and controlling parasite transmission by the means of selective therapy. Two Danish studies illustrated that one or two yearly strategic treatments applied to all horses are advisable to effectively break the life cycle of large strongyles, particularly the bloodworm, Strongylus vulgaris. In other words, a basic foundation of treatments can be defined, upon which the some of the more parasitized horses can be identified to receive additional treatments with a selective approach. Several presentations underlined the need for yearly routine evaluations of the efficacy of the anthelmintic drugs used on each farm. The fecal egg count reduction test is the most important use of the fecal egg counts. [Weese comment: that's when you do a fecal egg count before and after deworming, and compare the egg counts to see how much they dropped, as an indication of how well the dewormer worked] Perhaps most encouraging was the promising new diagnostic tools presented by several groups for detection of migrating or encysted parasite larvae. These will turn very useful for identifying horses at risk of disease and in need of deworming. One of these, developed by Jacqui Matthews and her group at Moredun Research Institute in Scotland shows great promise for measuring burdens of small strongyle larvae (cyathostomins), which can pose a threat for severe parasitic disease. With these new tools in hand, we will become able to further refine our recommendations in the future.
Discussion is ongoing about whether sinks are needed in the exam room now that hand sanitizers are available.
- I'm not sure who's discussing this. Hand sanitizers are great and should be used as much as possible, but that doesn't mean handwashing is obsolete. Some pathogens we deal with are resistant to alcohol, such as parvovirus, Clostridium spores and ringworm. We need to wash hands when these bugs might be present. Hand sanitizers also don't help if you have chunks of pus, blood or feces on your hands. If there's no sink in the exam room, handwashing usually won't be done when it's supposed to be. If someone has to leave the room and walk to a sink, it just doesn't happen often, even if it's a short distance. A person also runs the risk of contaminating other surfaces along the way, between the exam room door and the sink.
Experts agree, however, that if you have a sink, your clients will expect you to use it to wash your hands.
- I'm not sure who these experts are, or what they're experts in. Certainly not common sense or infection control. What they're implying here is that pet owners will think veterinarians aren't doing a good job if they see a sink and the vet doesn't use it, but that if no sink is present, no one will think twice about a vet failing to practice good hand hygiene. If an owner is going to clue in to the presence of the sink and failure to wash hands (something we should be encouraging), their common sense and observation skills won't evaporate if there's no sink.
This is similar to an interview with an architect on dvm360.com where the guy says "if I have a sink I better wash my hands or the client thinks my hands aren't clean. In many cases it's better off not to have a sink..." (note: the banging you hear is me hitting my head against a wall). The same architect cited in this article, so hopefully he's actually the only one pushing this approach.
Pet owners aren't dumb.
Infection control isn't rocket science.
Handwashing is important and under-used.
We need sinks in exam rooms.
Common sense needs to be more common.
It's difficult to put sinks in existing exam rooms - some clinics just can't do this easily. That's tolerable if they are diligent in their infection control practices, use hand sanitizers as appropriate and make sure they get to a sink (without contaminating things along the way) when they need to wash their hands. Not putting sinks in a newly designed clinic is just dumb.
When I give talks about methicillin-resistant staphylococci, I almost invariable get into a discussion of the risks of methicillin-resistant S. pseudintermedius (MRSP) in people. This bug is becoming increasingly common in dogs and because it's so resistant to antibiotics, there's concern about whether it can be transmitted to people.
My usual answer is that there is a low risk of MRSP infection in people, but not no risk. MRSP is no more likely to cause an infection in a person compared to it's antibiotic-susceptible counterpart, regular S. pseudintermedius (the resistant version is just harder to treat). Most dogs carry susceptible S. pseudintermedius in their mouths, nose, skin, ears and/or intestinal tracts, so people in contact with dogs are very commonly exposed. Yet, human infections seem to be quite rare. There are periodic reports in the medical literature about S. pseudintermedius infections in people, but they tend to be single case reports, and when someone can publish a report of a single infection in person, you know it's pretty uncommon (since if it was common, no journal would be interested).
That's my long-winded way of introducing a recent case report in the Journal of Clinical Microbiology (Hatch et al. 2012). The patient in the report was an elderly man with underlying disease, so someone who was at high risk of infection from bugs that don't often affect otherwise healthy people. He had skin lesions, sore joints and a bloodstream infection, and "S. intermedius" (I'll get to the name issue later) was isolated from his blood. Fortunately, he was successfully treated. He owned a dog and that was (reasonably) considered to be the source of the bacterium, but no testing was done to look into that. So, from a disease standpoint, it's not really a surprising case - just another in a series of very rare infections that have happened.
The other issue here is the fact that the authors (along with the diagnostic lab, the journal's reviewers and the editor) are behind the times and don't realize that it's virtually guaranteed that this person didn't have a S. intermedius infection. Rather, it was presumably S. pseudintermedius, or perhaps another similar staphylococcus. It wouldn't have much of an impact on this particular case, although not knowing the species probably also indicates the lab doesn't know that there are different breakpoints to determine if the bug is methicllin-resistant, and there's the potential they would miss methcillin-resistant S. pseudintermedius and use an inappropriate and ineffective treatment (fortunately that didn't happen here).
I've had a few (well... more than a few) calls about potential risks to animals from the large Canadian E. coli O157 beef recall. The main concern is for dogs that are fed potentially contaminated raw meat that has been recalled, but there is also potential for exposure through cross-contamination if people in the household consumed any suspect products, and through dogs getting into garbage containing meat packaging. The other issue is whether dogs and cats can become exposed, start shedding the bacterium in their feces and subsequently infect people. Contamination of a pet's food bowl leading to human exposure is also a potential concern, especially considering the fact that as few as 10 of these E. coli bacteria can cause infection in people.
Overall, these risks are quite low. The contaminated meat is primarily a human concern. The role of E. coli O157 in disease in dogs is pretty unclear, but there's no evidence it's a significant problem. Experimentally, disease can be induced in dogs fed relatively high numbers of E. coli O157, but natural disease seems to be rare (including in dogs on beef farms where exposure is probably relatively common). I think it's reasonable to suspect that this strain of E. coli can cause disease in dogs, but it doesn't happen very often. We also don't recognize hemolytic/uremic syndrome (HUS) in dogs (the severe form of E. coli O157 infection that can cause kidney disease in people).
The risk to people from recalled meat is real. The risk to people from pets is pretty remote. Studies have not identified pet contact as a risk factor for human E. coli O157 infection. Dogs have been implicated as vectors in a limited number of specific household situations, albeit with rather weak evidence and only when focused on people and animals on beef farms.
Overall, the risks to pets and from pets are pretty limited. The main concern with the recalled meat is human disease. That being said, I wouldn't recommend people feed recalled meat to animals instead of disposing of it, since there is a possible though slight risk to both humans and animals.
A Wyoming (USA) dog has died of necrotizing fasciitis (more popularly and dramatically known as "flesh-eating disease"). This isn't unheard of in dogs, but it's a pretty rare disease. The six-year-old Great Dane's infection apparently raised some concern because of the diagnosis of necrotizing fasciitis in three people in the area. However, there is no known connection between the dog and the human cases.
While not anything new, the case is noteworthy for a few reasons, not the least of which is the high mortality rate associated with this disease. A few different types of bacteria can cause "flesh-eating disease," but streptococci are most common. The news reports say the dog had Group A strep, which is quite surprising and raises a lot of questions, such as:
- Was it really Group A strep? Most of these infections in dogs are caused by a related bug, Streptococcus canis, which is a Group G strep. Group A strep is essentially unheard of in dogs and I have to wonder whether the bacterium was misidentified by the lab or the reporting is inaccurate.
- If it actually was Group A strep, what's the public health concern? Group A strep is a common bug in people (the one that causes strep throat) but invasive infections like necrotizing fasciitis are a much bigger concern, and potential dog-human transmission would have to be considered.
- If this was Group A strep, are public health authorities taking the same steps was they would in response to finding Group A strep necrotizing fasciitis in a human in the household (such as the Public Health Agency of Canada's Guidelines for the Prevention and Control of Invasive Group A Streptococcal Disease?) This would make sense to me.
- If this was really Group G strep (the most likely scenario), did the dog receive a fluoroquinolone antibiotic before the infection set in? It doesn't sound like that was the case from the article, but knowing for sure would be interesting. Most cases of Group G strep necrotizing fasciitis that we see are associated with enrofloxacin treatment of an initially mild infection, since this drug can induce increased virulence in Group G strep.
Regardless of whether it was Group A or Group G strep, it's an unfortunate situation for the dog and the family, but people shouldn't be too concerned because this is a very rare, sporadic disease in dogs and one that has not been linked to any risk to other species.
Earlier this year, a troop of Boy Scouts in the US beat off a rabid beaver that was attacking their leader (I wonder if there's a badge for that). Boy Scouts and infectious diseases are in the news again, but not with as happy a story.
In the recent incident reported on ProMED, ten Boy Scouts that attended a camp on the banks of the Semois River in Belgium developed leptospirosis - a potentially severe bacterial infection caused by Leptospira bacteria. The bacteria are shed in the urine of a variety of animal species, and people can become infected through contact with contaminated water or animals. The boys reported having played with a rat, which was likely actually a muskrat, based on the description of its size.
Three of the boys were hospitalized. Hopefully all are on the way to recovering.
This is yet another reminder that wildlife should be left alone. It's possible the boys were infected from the environment, but handling a muskrat (which was presumably sick if they were able to get that close to it) certainly increases the risk of exposure to a variety of infectious diseases.
Image of a North American muskrat (photo credit: Linda Tanner)(click image for source)
It's perhaps a good sign for public health when I don't tend to come home from a local fair and write a rant about the sorry state of the petting zoo. Around here, things seem to have improved at most events over the past few years, probably largely because of the efforts of local public health personnel. However, some establishments still fall through the cracks and regardless, even with optimal management, there's always some degree of risk with contact between animals and the public.
Welsh authorities are investigating a small (so far... and hopefully to remain that way) outbreak of E. coli O157 that has been tentatively linked to Cantref Adventure Farm. The two children became ill after visiting the farm. Two family members of one child have also tested positive for the bacterium, and it's believed that one of them was infected via contact with child (as opposed to direct contact with animals at the farm). Since both kids visited the farm in the days before they got sick, and since petting zoos are a prime source of E. coli outbreaks, it's logical to assume the farm was the source. Even though this has not yet proven, the reason to make this early assumption before a link can be definitively established is to get the word out to others that may have visited the petting zoo, in case there are more cases of illness. Authorities are telling people who visited the farm since the beginning of August to contact their physician. It's not clear whether they want to test everyone (by collecting a stool sample) or just have them checked out to make sure they are okay.
Meanwhile, the investigation at the farm is ongoing. Presumably, stool samples from animals on the premises and environmental samples have been collected to see if the same strain of E. coli is present. All direct contact between the public and animals on the farm has been stopped, and the site is being thoroughly cleaned. That's a pretty standard response overall, and hopefully if the petting zoo was the source, transmission has ceased.
Petting zoos can be fun and educational and we don't want to over-react and assume they are all inherently dangerous. There's always some degree of risk of infectious disease exposure, and the key is making sure petting zoos are run optimally to reduce, as much as possible, the risk to the public. The public also has to play a role, by following rules, supervising children and (probably most importantly) actually using hand sanitizers and handwashing stations that are provided.
.Dirofilaria immitis is the parasite that causes heartworm in dogs (and rarely cats). This mosquito-borne parasite can cause serious disease in dogs, and a lot of effort is spent trying to prevent heartworm infection. It can also cause disease in people who are bitten by a mosquito that has fed on an infected dog, but human infections are quite rare and of limited health risk. The main concern with regard to human infection is that it can create a small mass in the lungs. The mass itself isn’t usually a problem, but if it gets seen on an x-ray, it may appear very similar to a lung tumour, potentially leading to the use of more invasive diagnostic techniques (e.g. lung biopsy) to rule out cancer.
Dirofilaria immitis is not the only species of Dirofiliria. In fact, there are mulitple different Dirofilaria species with different hosts, some of which can also rarely infect people.
When it comes to dogs, D. immitis is the main concern, but dogs are also the host of Dirofilaria repens, which is most common in Mediterranean countries, eastern Europe and sub-Saharan Africa. Now, there’s a new one to add to the list, based on a paper in the Journal of Clinical Microbiology (To et al. 2012) that describes a novel Dirofilaria species in Hong Kong. Interestingly, it was found first by identifying disease in people.
Three human cases were identified in Hong Kong over a 10 month period in 2011-2012. When the researchers recovered the parasite from these individuals, they determined that, while it looked like other Dirofilaria, it was genetically different from any known species. They have tentatively named it «Candidatus Dirofilaria hongkongensis» (not very original but descriptive).
They then tested blood samples from 200 dogs and 100 cats, and found a parasite in six dogs that was identical to the new Dirofilaria from the human patients. They also tested the dogs with a commonly used commercial heartworm test that detects D. immitis and they were all negative, except for one dog that was actually infected with both the new species and D. immitis.
This is an interesting report and shows the need to be aware of potentially emerging issues. Some important questions need to be answered:
- What’s the risk to people? Obviously it can cause disease, since the three people in this report were actually sick. However, is this a very rare condition or something that may be more common? Is it something that’s been around for a long time and not diagnosed or is it really new?
- How do people get infected? They presumably get it from being bitten by an infected mosquito (as for other Dirofilaria) but how does the mosquito get infected? Are dogs the main source, one of many sources or are they inconsequetial?
- Does this new Dirofilaria cause disease in dogs? The six positive dogs were healthy, at least at the time of testing. Heartworm caused by D. immitis is a gradually progressive disease, meaning the signs become worse over time, so the fact that these dogs were clinically normal doesn’t mean there’s no risk, as they could start showing signs later on.
- What is the risk outside of Hong Kong? It’s hard to say because we know so little about this parasite, but it’s probably limited, at least at this point in time.
I’ve written about lymphocytic choriomeningitis virus (LCMV) before, as an interesting but pretty uncommon rodent-associated disease. Human infections are mainly associated with handling rodents, although other routes of transmission, such as organ transplantation from an infected donor, have also been reported. Being a disease associated with rodents and considering how rodents are produced in North America (i.e. mass production in large breeding colonies, followed by transportation to large distributors and massive mixing of animals), LCMV is bound to be a recurring problem associated with the pet rodent trade.
An issue of the CDC's ominously titled Morbidity and Mortality Weekly Report describes the risk of infection with LCMV to people who work in rodent breeding facilities. It all started with the diagnosis of meningitis in a person who worked in a rodent breeding facility in Indiana. An astute doctor suspected LCMV and the diagnosis was confirmed. The breeding facility was a pretty large one, housing approximately 155 000 (!) mice and 14 000 rats. An investigation of facility personnel ensued and approximately 25% of employees had antibodies against the virus, indicating previous infection. A large percentage of the workers reported having had signs consistent with disease (e.g flu-like illness), indicating that they were likely infected and not just exposed.
Considerable effort was put into testing the animals. Of over 1000 animals tested, 21% of mice had detectable levels of the virus in their bodies. That’s pretty impressive and concerning, both for employees and anyone receiving animals from this facility.
In response to this investigation, all mice at the facility were euthanized, and the facility was thoroughly cleaned and disinfected.
This report highlights the risk of exposure to LCMV for people who work with rodents, especially in large facilities such as this. It also highlights the risks posed to people buying rodents from these facilities, which also includes other diseases in addition to LCMV. Good general hygiene and infection control practices should greatly reduce the risk of LCMV transmission to rodent owners. In particular, efforts should be directed at new rodents, since LCMV shedding is probably greatest during the initial period after an animal enters a household or other facility. Virus shedding it often transient, and once they get out of the high-risk facility and become acclimatized to their new home, shedding rates in these rodents probably decrease over a short period of time. Overall, the risk of LCMV in someone with a pet rodent is low, but these basic preventive practices are easy to do and make a lot of sense.
Photo: Female mouse with her litter. (Photo credit: Seweryn Olkowicz) (click image for source)
When bacteria containing NDM-1 (New Delhi metallobetalactamase 1) were first identified a few years ago, I talked about it during presentations as something bad that's coming our way. NDM-1 is an enzyme that gives the bacteria that possesses it resistance to a huge range of antibiotics, to the point that few or no viable treatment options are available. Given the close relationship between animals and humans, I figured it was only a matter of time before cases were identified in animals, especially household pets. A presentation by an FDA researcher at the 2012 Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) has confirmed the finding of NDM-1 in E coli from a pet cat in the US. I can't take much credit for foresight because it was pretty predictable, but it re-affirms concerns about emerging diseases and how infectious pathogens can move between people and animals.
Not much is known about this current case, since the E coli isolate was submitted for testing as part of a large ongoing surveillance study by Dr. Dawn Boothe of Auburn University. At this point, it's unclear whether the cat had been on antibiotics earlier, whether the owner had been diagnosed with the infection, whether the owner had traveled to areas where this bug was first found (e.g. India), and other relevant pieces of information remain unknown (or at least unreported).
The cat was positive for the NMD-1 E.coli on multiple samples. The most intriguing aspect of this case is the fact that the culture samples from the cat were collected in 2008 and 2009 - at least a year before NDM-1 was first identified in the US. That's strange and concerning, and raises lots of questions about where this super-E.coli originated.
Some possible origins of the NMD-1 E.coli in this cat include:
- The owner may have traveled to an area where the bug was present, became a carrier and spread it to his/her cat upon returning home.
- The owner could have been infected when traveling, but it the infection may have been minor such that it didn't require medical care or a culture wasn't taken (so no one knew it was being caused by a super-bug), and subsequently the owner passed it on to the cat. (Remember that NDM-1 is a major concern because very few antibiotics are effective against it. However, the enzyme doesn't make the bacterium that carries it inherently more able to cause disease, so minor infections are possible.)
- On ProMed, the moderator stated that he believes stowaway rodents from India or Pakistan likely carried the bug to the US and spread it amongst other rodents, with eventual exposure of the cat through catching an infected rodent. It's possible but it's a major stretch, in my opinion.
- Perhaps the cat came from one of those endemic regions. That's pretty unlikely but there's a lot of animal movement around the world, with very little regulation, so it is possible.
We may never know how this cat got infected, but this case should be a reminder that we need to pay attention to animal populations in parallel with the human population. I keep saying it, but getting action has been difficult. People like to talk about "One Medicine," but actually getting people to practice "One Medicine" has been easier said than done.
a) there are more rabid beavers these days,
b) rabid beavers have always been around in these numbers but they have recently acquired a taste for human flesh, or
c) it's just a fluke,
The latest incident involved a beaver in West Springfield, Virginia that chased after some kids at a nature centre. The kids had been swimming and saw a beaver swimming towards the dock. It's not that unusual to see beaver's swimming around in some areas, but like most wildlife, they typically stay away from people. Not this one though. It "leaped out of the water onto the dock, acting aggressively and chasing the children." Police shot the animal and testing confirmed it was rabid. Presumably, no one required post-exposure treatment since there were no bites.
While rabid beavers are rare, this and earlier incidents involving attacks by rabid beavers, otters and other critters highlight some basic principles regarding rabies safety:
- Stay away from wildlife.
- Mammalian wildlife that are acting abnormally, including displaying no fear of humans, should be considered rabid until proven otherwise.
- Any bite by a wild mammal should be considered a potential rabies exposure. The animal should be tested whenever possible and if it can't be shown that the animal wasn't rabid, it must be assumed that there was rabies exposure.
Common sense goes a long way toward avoiding rabies exposure, but sometimes it's not avoidable. Knowing what to do in the event of a bite from a wild and potentially rabid animal is important. The key is involving physicians and public health personnel who understand rabies exposure risks, so that a proper risk assessment can be done and treatment can be started promptly if it's indicated.
Image: A North American Beaver (Castor canadensis), by Laszlo Ilyes (click image for source)
If you ask people about tapeworms, they typically think about the "ick" factor of having a large worm in their gut, but they probably don't get too concerned. However, some types of tapeworm infection can be serious health problems in humans and animals. One of the worst is infection by the tapeworm species Echinococcus multilocularis. A couple of recent reports about E. multilocularis in Canada have received a lot of attention.
With Echinococcus, the problem isn't the worm living in the intestine. Adult worms live in the intestinal tract of only "definitive hosts," which are primarily foxes and coyotes in North America. The worms aren't necessarily a problem for these animals, but they can pass large numbers of tapeworm eggs in their stool. The parasite's normal life cycle continues when small animals (e.g. rodents like mice and voles) swallow a tapeworm egg. The parasite then develops into a cyst in the animal's body, and if/when the little critter is eaten by a fox or coyote, the cyst gets eaten too and the fox/coyote develops a new adult tapeworm in the intestinal tract.
When it comes to people (and some other domestic species), the problem is what happens when they ingest tapeworm eggs. Like in rodents, the eggs hatch and the immature parasites migrate through the intestinal wall, and can then spread to virtually any place in the body. They can then develop into large cysts that, over a long period of time, result in serious disease. Large cysts and/or cysts in critical areas (e.g. the brain) can be devastating. Treatment is difficult, prolonged and expensive, and death rates are high.
Dogs are a bit of an oddity in this cycle, since they can carry adult tapeworms (not surprising, since they are similar to foxes and coyotes) but they can also get these large tissue cysts. From public health and infection control standpoints, dogs shedding Echinococcus eggs are the main concern, but cysts are potentially devastating in the rare dog that develops one, just as they are in people.
Recent concerns revolve around two papers, one that described a dog from British Columbia with Echinococcus cysts (Jenkins et al. Emerging Infectious Diseases 2012) and a study that identified E. multilocularis eggs in feces from 23/91 (25%) urban coyotes in Alberta (Catalano et al. Emerging Infectious Diseases 2012).
What's the risk in Canada?
It's low. Actually it's very low, and there have been only a handful of cases diagnosed even in people in North America. But with a serious disease like this, you can't ignore it. If Echinococcus is spreading in coyotes and foxes, it creates the potential for exposure of other species (including humans). The risk gets higher as coyotes and foxes get closer and closer to people and dogs, as is happening in some areas because of urban sprawl. The more coyotes that are around and the closer they are to human populations, the greater the chance that a person or dog will inadvertently ingest a tapeworm egg from coyote feces. Dog parks may be of particular concern because of the high traffic through them and the potential for them to be a big mixing site between wildlife, pets and humans.
There shouldn't be any panic because of this, as it still remains an extremely rare disease. But, it's not much consolation that it's a rare disease if you're the one with a big Echinococcus cyst in the brain. So, while the risk is low, we don't really know (yet) whether it's changing, and it's worth using some basic practices to reduce the risk. These include:
- The standard: Don't eat poop. Pretty straightforward but easier said than done, in many respects, since fecal contamination of the environment is pretty common. Avoiding inadvertent ingestion of feces can be done through proper handling of dog and wildlife feces and attention to handwashing.
- Controlling rodents and preventing pets from catching and eating rodents.
- Preventing dogs from eating wildlife feces.
- Routine tapeworm deworming should kill Echinococcus and if a dog is at particularly high risk, more regular testing and treatment for tapeworms may be indicated. Not many dogs fit into that category at the moment, though.
Image: Echinococcus multilocularis isolated from a fox in Hungary. Unlike the very long tapeworms of the Taenia genus, which are most commonly found in dogs and cats, Echinococcus tapeworms are quite small (the bar in the picture is 0.5 mm), but the eggs shed in the feces of animals with an intestinal infection (involving mature adult worms) are virtually identical to those of Taenia spp. (click image for source).
The annual US rabies surveillance report has been published in the latest edition of the Journal of the American Veterinary Medical Association (Blanton et al 2012). There's not really anything earth-shattering in it, but it's a good overview of the rabies diagnoses in the US from 2011. As always, it only provides a peek into rabies in wildlife (since only a small percentage of wildlife with rabies get diagnosed and reported) but numbers and trends in domestic animals, along with general wildlife data, provide useful information about the state of this virus in the US. Among the highlights:
- Rabies was diagnosed is 6031 animals and 6 people, from 49 states and Puerto Rico (Hawaii remains rabies-free). This is a 2% drop in animal cases from 2010, but I don't put much stock in that because the numbers are weighted towards wlidlife cases, and it's hard to have confidence in year-to-year numbers of rabid wild animals (because it's so dependent on what actually gets tested).
- The main wildlife species that are involved in maintaining the rabies virus in the US (reservoir species) continue to be raccoons, bats, skunks and foxes on the mainland, and mongooses in Puerto Rico. The relative importance of these species varies between regions.
- Raccoons were the most commonly affected species, accounting for 33% of all rabid animals reported. Other leading species were skunks (27%), bats (23%) and foxes (7%). Less common species included coyotes, bobcats, javelinas, deer, otters, mongooses, wolf hybrids, groundhogs and beavers.
- Cats were the leading domestic animal, with 303 diagnosed cases. Dogs came in next with 70, followed by cattle (65), horses (44), and goats and sheep (12). There were also single cases in a domestic bison and an alpaca.
- The six human cases represent the highest annual number of cases since 1994, if you exclude 2004 where four cases were associated with transplantation of organs from a single infected person. In a review of the 24 domestically-acquired human cases from 2002-2011, 88% were linked to bats.
- Three of the six 2011 human cases were acquired outside of the US; one each from Haiti, Afghanistan and Brazil - and all from dogs.
- Two of the three domestically-acquired cases were associated with bat contact. The source of the remaining case, an eight-year-old girl, is unknown, but contact with cats from a feral colony near the girl's school is a possibility.
- 5/6 people with rabies died. That's actually an impressive survival rate, since any survival is still a very noteworthy event when it comes to rabies. The survivor was the eight-year-old girl, and she apparently has suffered no longterm cognitive impairment.
Interestingly, we get a good synopsis of Canadian rabies data in this report too:
- 115 rabid animals were identified, with 92% being wild animals.
- There were three rabid livestock (two of which were horses) and six dogs and cats.
- No rabid raccoons were identified, continuing a trend started in 2009.
And regarding rabies in Mexico:
- 148 rabid animals were identified, mainly cattle (82%).
- Rabies was diagnosed in 20 dogs, with evidence that the canine rabies virus variant (which has been eliminated from Canada and the US) is circulating in some regions.
- There were three humans cases: two acquired from vampire bats and one from a skunk.
The Guelph Humane Society has re-opened after a temporary closure to manage a potential ringworm outbreak. The shelter took an aggressive, proactive approach to the issue, including testing and treatment of all animals and thorough disinfection of the facility.
Looking back on a proactive outbreak response like this one, it's always hard to say if a bad outbreak didn't develop because it wasn't going to, or because of the early aggressive response (i.e. did it get better because of what they did or despite what they did). However, if you sit back and wait (or remain in denial), you can be sure that it's much more likely that badness will develop.
Once things have settled down, people sometimes complain that an aggressive response was unnecessary because nothing bad happened, but they're often the same people that complain that not enough was done when an major outbreak occurs. An ongoing challenge in infection control is fighting complacency, since successful infection prevention and control programs sometimes lead to people forgetting about the bad things that can happen and why such programs are in place to begin with. We should applaud facilities that "suck it up" and accept the negative PR, time and financial consequences of an appropriate response in order to protect the health and welfare of the animals for which they care and all the people (employees and public) who have contact with them.
When I give talks about pet therapy animals, I talk about appropriate and inappropriate animals. On one slide I have a picture of a hedgehog, and I use it as an example of an animal that sometimes makes its way into pet therapy programs, despite standard guidelines to the contrary. This is a species that raises significant infectious disease concerns because hedgehogs can carry an impressive array of microorganisms that can be spread to humans. A big one is Salmonella.
So, it doesn't come as too much of a surprise that the CDC is reporting a multistate outbreak of salmonellosis associated with hedgehogs. Here are the highlights:
- Fourteen infections have been reported between December 2011 and August 2012. There are probably many more because in most outbreaks, only a minority of affected people get tested.
- People have been infected in six states (Alabama, Indiana, Michigan, Minnesota, Ohio and Washington), all with the same strain of Salmonella Typhimurium.
- All 10 people that were interviewed reported contact with hedgehogs or their environments. Considering the rarity of hedgehogs as pets, that's a pretty good indicator that hedgehogs were the source. The outbreak strain of Salmonella was detected in two households, in areas where the hedgehogs lived or were bathed.
- No one has died, but three people were hospitalized.
- As it typical, a large percentage (50%) of affected individuals were children 10 years of age or under.
The fact that this outbreak appears to have occurred over a long period of time and a large geographic area strongly suggests that this might be ultimately traced back to a common breeder or intermediary source. Many small pets like these are mass produced by large breeders and shipped across the country, creating the potential for a problem at a single breeder to have far-reaching consequences in other breeder colonies and in households. This has been shown repeatedly with species like hamsters and mice.
This report doesn't mean that hedgehogs shouldn't be kept as pets. However, hedgehogs do seem to be a higher-risk species than average, and households that include high-risk individuals (e.g. young children, elderly persons, immunocompromised individuals, pregnant women) should probably avoid them. More importantly, the potential for transmission of Salmonella and other pathogens indicates the need for good basic, routine hygiene practices, such as washing hands after handling a hedgehog, keeping them out of the kitchen, not bathing them in kitchen or bathroom sinks, and supervising contact between hedgehogs and kids.
I'm not really sure what to think about canine norovirus. Is it a rare, oddball infection or is it an important, overlooked and/or emerging problem?
- There are only a few reports of norovirus infections in dogs, but I doubt many people are looking for it.
- I've looked for it a few times during outbreaks, but not enough to convince me it's not here.
- Most outbreaks of canine gastrointestinal disease are not investigated, and norovirus testing isn't commonly available.
So, I think it's hard to say much about this bug at the moment.
However, another outbreak report involving canine norovirus (Mesquita and Nascimento, Transboundary and Emerging Diseases 2012) has been published, increasing concern that this might be an overlooked or developing issue. This latest report from Portugal describes an outbreak in a kennel that started after the introduction of some dogs imported from Russia (yet another example of the problems that can occur with dog importation, especially in the absence of good quarantine and infection control practices).
The outbreak started after two dogs from Russia were brought into a Portuguese kennel. Both had diarrhea at the time of arrival (strike 1 - introduction of new dogs, particularly sick dogs, is just asking for an outbreak) and were put into the general dog population (strike 2). Two days later, the other five dogs in the kennel developed diarrhea (not surprising). All were positive for canine norovirus (ok, that's surprising) and within one week, all the dogs appeared to have fully recovered.
There's no mention of whether testing for other causes of diarrhea was performed, but I assume that's the case. The sudden onset, rapid transmission and relatively short, self-limiting course of disease is consistent with norovirus infection.
Canine norovirus has been found in Portugal before, and the virus found in these dogs was very similar to previous Portuguese isolates. Whether that means the dogs acquired the virus in Portugal en route to the kennel or whether this virus is widely disseminated internationally isn't clear (in large part because so few people have looked for canine norovirus).
Much more remains to be learned about this virus. It should be considered in outbreaks of diarrhea in dogs, especially outbreaks involving rapid transmission between animals. A major obstacle to obtaining more information about this pathogen is the general failure to investigate outbreaks in which it may be involved. While outbreaks are often dramatic, testing is usually limited because of the cost. That's especially true when dogs aren't dying. Often, testing for rare or potentially new problems only occurs when there's a complete disaster and/or if an interested researcher or diagnostic laboratory gets wind of it and is willing (and able) to do some testing at no cost. That's not often an option. I do testing as much as I can, but I don't have any money dedicated to outbreak investigation so it depends on whether I have spare resources to put into an investigation at the time.
The risk to people from canine norovirus is not known, but is probably limited. There is some evidence of potential transmission of noroviruses from pigs or calves to people, but the risk from canine norovirus isn't clear. Common sense practices to avoid contact with diarrhea (from any animal) should be used, as much to prevent exposure to the pile of other pathogens that can be in dog poop, as to prevent potential exposure to canine norovirus.
An 8-week-old puppy in Van Buren County, Michigan has died from infection by a virus that normally infects horses. This is a rather rare occurrence of a nonetheless devastating infection. The puppy was euthanized after developing seizures and other neurological abnormalities, and Eastern equine encephalitis (EEE) virus infection was ultimately diagnosed. Testing for this and other viruses was probably undertaken because of concerns about rabies.
EEE virus is a mosquito-borne virus that circulates in the bird population and is spread by mosquitoes. Horses are the main victims of infection but disease can occur in various other mammals, including people and dogs.
Canine infections are very rare and this can be considered an "oddball" infection. There's no evidence that dogs are at any elevated degree of risk compared to previous years, but it is a reminder that while infections are rare, dogs can be susceptible to EEE. The puppy's young age probably played a role and certain groups (e.g. puppies, elderly dogs, dogs with compromised immune systems) are presumably at greater risk of illness than the normal dog population. The other obvious implication of this report is that it is clear that EEE is circulating in mosquitoes in the area. That means other susceptible species, namely horses and people, are also at risk of exposure.
EEE in people is pretty high on the badness scale. It's fortunately rare but when it strikes, it's usually fatal. The same is true for horses. There is a vaccine for horses but not for people, so the main protective mechanism for people is mosquito avoidance.
As with EEE in horses, infected dogs pose no real risk to humans. The virus is not spread by regular contact and dogs don't develop high enough viral levels in their blood to be able to infect more mosquitoes (who could then infect people). There's a potential risk of transmission through contact with infected tissues during post mortem examination (necropsies) but standard practices used to prevent transmission of other diseases (e.g. rabies) should be effective for EEE as well.
After being a relatively rare problem in most regions over the past few years, West Nile virus (WNV) case numbers have boomed lately, with large outbreaks in some US states.
Forty-nine (49) confirmed or probable human cases have been reported in Ontario, the largest number in a decade. Considering we're just heading into the typical peak WNV season, it's quite concerning as the worst may be yet to come. At this time last year, there were only 24 reported cases.
Human cases have been reported in at least four other provinces: Alberta, Manitoba, Saskatchewan and Quebec.
Two equine cases of WNV have been reported, one in Saskatchewan and one in Quebec. It's hard to have a lot of confidence in this number because of the poor surveillance and reporting for this disease in animals in Canada, given that the CFIA has largely washed their hands of dealing with it. Infection with West Nile virus has been pretty much a non-entity in most regions over the past few years, at least in terms of diagnosed cases, and it remains to be seen whether equine cases will mirror the spike in human cases this year. Typically the trends are similar each year, so the next few weeks will tell us a lot.
The US is in the midst of its largest WNV outbreak ever. At least 1118 human cases have been reported so far in at least 37 states, with at least 41 deaths. Typically less than 300 cases are reported by this time of year. Texas has experienced a huge outbreak, accounting for about half of the US cases.
There hasn't (apparently) been a surge in equine cases, with less than 100 cases of WNV reported in horses as of August 18. Whether that's because of infrequent testing, biological or geographic factors resulting in less equine exposure or vaccination of horses (remember that there is no WNV vaccine for people) isn't clear.
Concern is being raised about risks to pets, but the true risk is very limited. While WNV infections have been reported in dogs and cats, these are extremely rare and dogs and cats are failry resistant to the virus.
Often, when a new infectious disease emerges, the first year or two are the boom years, after which things settle down. That was the pattern with WNV in most areas; however, this year in on track to meet or surpass the numbers from those early years.
Why is this happening? No one knows for sure. Changing weather patterns, by chance or through the larger spectre of global warming, are probably playing a major role. Warmer temperatures let mosquitoes mature faster and allow the virus to grow quicker in the mosquitoes. Milder winters help mosquitoes survive. Any factor that fosters more mosquito numbers and growth, particularly the subset of mosquitoes that bites both birds (the reservoir of the virus) and people, can increase the risk of human and animal exposure. Changes in rainfall, wetland management, climate and human proximity to mosquito breeding sites can all play a role.
'Tis the season for ringworm, I guess.
The Guelph Humane Society has closed to visitors, and adoptions have been suspended in response to concerns about the potential for a ringworm outbreak. Implementing a proactive response, all animals are being tested for ringworm and all cats are being treated. While the scope of the problem isn't yet clear (and hopefully it's minimal), this type of response is the optimal approach because waiting to "see what happens" and waiting for culture results (which can take a long time) before deciding to take aggressive measures results is a much greater chance of things getting out of hand.
In an outbreak like this, the first week or so is critical. Introduction of an animal that's carrying ringworm is hard to prevent, as is limited transmission within a shelter (even with good routine infection control practices) from that first case. That's the non-preventable component of shelter diseases. However, it's the 2nd generation of transmission (transmission of ringworm from that initial animal or group of animals to the broader population) that leads to things getting out of control. That's the preventable fraction of infections, on which we can have the biggest impact. It's during this early phase where intervention is critical It's always better to have an overly aggressive response and simply tone it down after a few days, than to have an inadequate response that lets things spiral out of control.
More information about ringworm can be found on the Worms & Germs Resources - Pets page.
A few years ago, I looked out my kitchen window one holiday morning and saw a newborn foal running outside of a fence line. The foal had been born to my neighbours' mare, a maiden mare, and they were out of town. The mare had rejected the foal and wasn't interested in any of my attempts to get them back together. She also had little colostrum (the first, antibody-rich milk that foals need to drink early in life to survive). To make a long story short, I ended up doing a field transfusion, collecting blood from another horse on the farm to give to the foal, to provide it with those much-needed antibodies. The donor horse was healthy and I didn't know of any disease issues in the area, so I was pretty confident that there wasn't a significant risk of disease transmission, but you never know. Ideally, equine blood donors are screened for infectious diseases, particularly equine infectious anemia (EIA), since EIA is a rare but nasty disease that can be spread by blood.
When I started to read a report the other day about a transfusion-associated EIA infection in a German foal, my first thoughts were "that's bad," followed by my ever-optimistic side thinking "well, maybe it was an emergency transfusion and it was a bad but unavoidable consequence" or "maybe it the donor was properly screened but was infected with the EIA virus after it's last test" (the latter situation is an ever-present risk when you are screening donors in advance (days, weeks or months) of collecting the blood for transfusion, since test results only tell you what their status was at the time of testing).
Unfortunately, it didn't take long to see that this wasn't an unfortunate or relatively unavoidable infection. Rather, I can only interpret this as stunning negligence.
Here's the story
- On August 2, EIA was confirmed in a 3-month-old foal in North Rhine Westphalia. When the foal was two days old, it had a septic joint (and probably an overall deficiency in antibodies) and was treated with a plasma transfusion, which is a pretty standard procedure in such a case.
- EIA antibodies were then detected in the donor.
- Since 2009, 20 other horses had received plasma from this horse. Four have been confirmed as infected, and horses that live with these infected animals have been quarantined until test results are back. Positive horses are typically euthanized because they pose a lifelong risk of transmission of the virus to other horses. The four positive horses in this case have been euthanized (and presumably the foal as well).
So, this wasn't some random emergency field transfusion, or a donor that got infected after testing. It appears that this donor has been used for years with no testing, despite the fact that it's well known that EIA transmission is a risk from blood transfusions and the virus is present (albeit rare) in Germany. While there are no standards of care for equine blood transfusions (as opposed to dogs), EIA testing is a standard recommendation in anything I've seen written about equine blood donor programs (click here for one example). Sometimes you get put into situations where testing can't be done in time for logistical reasons, but I can't see how anyone would not test horses that are to be used for a formal donation program or repeated transfusions. Failure to do low cost and easy EIA screening of that donor horse has resulted in the deaths of multiple horses, with the potential for even broader secondary transmission of this virus to additional animals.
The scope of the outbreak isn't really clear from press reports, but "a couple" of other animals now have signs of the skin disease. Investigation of the timing and likely sources of exposure of new cases is crucial. They may just be animals that were infected early, before the problem was recognized (the best case scenario) but investigating these "new" cases is very important because if these animals were exposed after the outbreak was identified, then there are problems with containment.
Shelter personnel have declared that they aren't planning on euthanizing more animals, but the shelter remains closed for adoptions. Stray animals will continue to be accepted. This creates a tricky situation where new animals (e.g. fuel for the fire, if things aren't under control) come in and can actually propagate the outbreak. It also creates overcrowding issues since the shelter was probably pretty full to start with, and continuing admissions with no adoptions can't be maintained for long. The shelter is looking at renting units in which to put animals - this is a relatively common approach for creating more contained spaces, and one that can be useful if good infection control practices are in place (although I've seen too many outbreaks where the offending pathogen quickly makes its way into the new units). Clear policies, sound training, careful supervision, exquisite planning and good communication are critical for making a situation like that work.
While the shelter has gone from an unrealistically optimistic time frame to a warning about long-term efforts, as with most things in life, the middle ground is usually the most accurate. Ringworm outbreaks can't be declared over in a few days (it's possible to contain it in a short period of time, but not declare an outbreak over). A few days isn't even enough time to get culture results back to figure out exactly what's happening. Testing, isolation, cohorting, mass treatment, evaluation of training, evaluation of infection control practices, and similar measures are needed, but if done right, an outbreak can be contained in a reasonably short period of time. Given the need to repeatedly treat all animals (affected animals are being bathed every three days with a medicated solution) and the time lag for ringworm culture, it's going to take at least a few weeks, but let's hope this outbreak ultimately gets measured in weeks rather than months.
It might just be my perception, but it seems like there are a lot more reports of nasty dog bite infections in the news lately, particularly infections caused by the bacterium Capnocytophaga canimorsus. I don't know whether that's because they are becoming more common, more commonly diagnosed (since the bug is hard to identify), more commonly reported in the press or a combination of all three (or whether my perception is simply incorrect).
The latest report is from Omaha, Nebraska, where a 50-year-old man died four days after suffering a minor dog bite on the cheek. The cause of infection wasn't reported, but the article says that he was unable to fight the infection because he didn't have a spleen. For me, minor bite + fatal infection + no spleen = Capnocytophaga infection until proven otherwise, since this is a textbook description of such an infection, and Capnocytophaga can be found in the mouth of virtually every dog.
This follows the high-profile case of a cancer survivor who lost her hands and feet from Capnocytophaga infection complications and a UK inquest into the death of a man caused by infection with this bacterium, among other cases.
Here are the simple take home messages:
- Avoid bites and any interactions whereby dog saliva may come in contact with non-intact skin.
- Know if you are at high-risk for an infection caused by a bug like Capnocytophaga. This bacterium typically doesn't cause disease in healthy individuals but can produce rapidly fatal disease in certain people.
- Realize that minor bites can cause major problems (even if you are otherwise healthy).
- Use good first aid practices if you or someone you're with is bitten, including careful washing of the wound and seeking medical care if you are at increased risk of infection, or if the bite is over the hands, feet, face, joints or other sensitive areas.
The facility was closed to the public on August 4th because three cats and one dog were showing unspecified signs of ringworm.
Samples were collected for testing, but they decided to euthanize the 4 animals.
"You’re kind of under the gun to decide what you want to do,” said their operations manager. I can certainly empathize. It's not easy to deal with an outbreak. However, from my standpoint, if you feel like you're under the gun in that kind of situation, you're likely to make (or to have already made) mistakes. If you're managing the situation well, getting advice and following standard practices, you may be stressed, exhausted, humbled and concerned, but you shouldn't feel "under the gun." Maybe euthanasia was warranted here, but with a small number of infected animals, the ability to potentially isolate and treat them, and lots of information about how to manage ringworm to avoid further spread, it's important to avoid a panic response that leads to premature euthanasia decisions.
The three cats that were euthanized apparently did not have ringworm, but the shelter is "certain" (not sure how) that the dog had ringworm. Sudden onset of skin lesions in dogs and cats at the same time is certainly suggestive of ringworm, and if the dog was truly infected, it's hard to believe the cats were not (especially since cats are most often affected in ringworm outbreaks compared to dogs). So I wouldn't be too quick to rule out ringworm in the cats. Ringworm culture can take a couple of weeks, so it's not clear to me whether this interpretation is based on culture results or not.
"With the results being better than expected, the humane society will not have to move larger numbers of possibly infected animals to a different facility — the usual procedure in an outbreak." While I can't say too much from a distance, I can say that moving animals to another facility is certainly not a typical outbreak response measure. It's an effective outbreak propagation measure, since it can easily disseminate ringworm to other places, so it's good to hear that they are not planning on moving animals. It's much better to manage things well at one site than to have to manage things at multiple sites.
They state that "the situation now appears to be under control." Hopefully that's true, but it's way too early to say. You can't declare an outbreak over a few days after you declare that it started. There hasn't even been enough time for any animal or environmental ringworm culture results to come back. Closing, testing, treating all exposed animals and thorough cleaning and disinfecting of the environment can be a great start, but trying to say "we won" too early often leads to inadequate response and continuation of the outbreak.
"We’re keeping our fingers crossed and hoping that everything comes back negative so we can be open for business sometime next week" Again, I'm not involved and I'm working with sparse information, but this seems to be way too early to reopen the shelter. You need to make sure things are really under control before you get out of "outbreak mode" and before you can be "open for business" again. That's especially true with a disease like ringworm that is highly transmissible and can be spread to people. Too often, a small outbreak is identified and declared over prematurely, only to be followed by a big mess in short order. Let's hope that's not the case here.
Image: Photo of a dermatophyte-positive culture specimen, which can take two weeks or longer to grow.
If I was reincarnated as a mosquito, I'd want to live where I do now (convenient, eh?). I live in the country surrounded by areas of "protected wetland," which, in many cases, is a fancy word for swamp. I try to avoid mosquitoes, but getting bitten is a regular (daily) event. As I was getting swarmed last night, I was thinking that the mosquito-borne disease I'm really concerned about is Eastern equine encephalitis (EEE). While quite rare in Ontario, with only a handful or no cases in horses every year, it's a worry because it's almost always fatal. It also affects people, not via transmission from horses but from being bitten by mosquitoes that pick up the virus from birds. It's very rare in people, but it's highly fatal.
This is the time of year that we start seeing mosquito-borne infections in Ontario, and a Disease Alert from the province re-inforces concerns about EEE. The alert was issued in response to a case of EEE in a horse in New York state, not far from the Canadian border. The horse, from the Ogdensburg, NY area, showed signs of illness on July 23 and died the next day (a pretty typical progression for this disease). Since mosquitoes don't respect borders, cases in this neighbouring region suggest that infected mosquitoes might also be active in Ontario.
EEE isn't the only mosquito-borne virus that we worry about - West Nile virus being the other main issue around here - so mosquito control and avoidance are important. While you can never guarantee that you or your animal will not encounter a mosquito, various things can be done to reduce mosquito numbers (e.g. eliminating sites of standing water (which are mosquito breeding sites) wherever possible... swamps being a logical exception) and to reduce the risk of being bitten (e.g. avoiding high risk areas and times, long clothing, mosquito repellants). Vaccines are available for EEE and West Nile virus in horses (but not people), and the risk of these diseases should be considered when designing a horse's vaccination program.
Rabies is most commonly reported in dogs, skunks, raccoons, bats and a few other species. However, any mammal is susceptible, and sometimes unusual cases are identified.
1. In a serious take on Monty Python's "killer rabbit," a rabid bunny has caused a lot of problems in Chom Thong, Thailand.
The pet rabbit, Poko, had been purchased last year and starting biting the feet of people in the family on June 10. The rabbit was eventually put in a kennel and died July 28. The other rabbit in the house died the next day (no word on why). The time frame is a bit strange, since if the rabbit was biting because of rabies, it should have died a lot quicker. Once an animal is showing signs of rabies, death occurs quite quickly (usually within 10 days), not over a period of 7 or 8 weeks. So, most likely the rabbit wasn't biting because of rabies, at least at the start.
In response to the diagnosis, authorities have launched an investigation and 120 health officials are fanning out in the area to look for other rabid animals, since where there is one, the are others. Dogs and cats within 5 km of the rabbit's home are being vaccinated against rabies. Family members are being given post-exposure prophylaxis. The father has expressed concern that the treatment was too late since they were bitten several days before, but it's not really much of a risk. Rabies typically has a long incubation period, especially with bites to lower extremities, and starting treatment a few days (or even weeks, in some situations) after exposure can still be effective (albeit the sooner the better). The key is for treatment to be started before any signs of rabies develop - after that happens there's very little that can be done.
The source of rabies isn't clear and I haven't seen any speculation. If the rabbit was caged, then there aren't too many possible sources, with bats probably being the most likely.
2. Swimmers beware... it's not just rabid otters you need to worry about.
A man swimming in eastern Pennsylvania was bitten by a beaver that was subsequently identified as rabid. The beaver apparently attacked a canoeist earlier that day, before encountering the swimmer, a Boy Scout leader. The man suffered 15 lacerations from the attack, and the beaver remained firmly attached to the man's arm as he was helped to shore. The stubborn critter wouldn't let go until the resourceful (and brave) Scouts got it off by hitting it with "anything they could find around them, sticks, rocks..." The beaver was killed and confirmed as rabid.
It's another reminder that any bite from a mammal should be considered a possible rabies exposure. It's also a reminder to avoid contact with wildlife, although that can be easier said than done when a rabid animal is involved.
While I'm certain I'll face more wrath from the keep-reptiles-in-schools group that is currently bashing me on the internet (there's even a Facebook page... at least I'm making an impact!), this brings up a few serious issues. One is the whole idea of putting a python around the neck of a young child. I won't go there, and in reality the risk of injury is very low. The main issue is, obviously, Salmonella exposure, because of the high rate of Salmonella shedding in reptiles and the high susceptibility of young kids to salmonellosis. A recent paper in Zoonoses and Public Health (Hydeskov et al. 2012) provides more evidence that the concerns about Salmonella exposure in such situations are valid.
- This study involved the reptile collection at the Copenhagen Zoo. There, the reptile collection consists of two groups: the main group is comprised of animals in the breeding centre, quarantine station and the primary zoo exhibit; the other group is a smaller collection that's used for education and hands-on teaching. The latter group has direct contact with many people, including kids.
- Salmonella was isolated from 35% of reptiles overall, with the highest prevalence in snakes (62%).
- Reptiles from the education group had a significantly higher prevalence than the other reptiles; 64% vs 23%.
- While these numbers are high, they are presumably an underestimation, since other studies have shown that you will miss a reasonable percentage of positive animals if you only test a single sample from each individual. So, it's fair to say that at least 62% of snakes and at least 64% of education-group reptiles were Salmonella positive.
Has the zoo ever been the source of Salmonella in a person? Nothing's been confirmed; however it's important to note that in Denmark, official investigation of salmonellosis cases only occurs as part of an outbreak. Since reptile-associated salmonellosis would most likely occur as sporadic cases, not an outbreak, cases might not be identified and reported.
It's also possible that the zoo hasn't been a source, because of the short-term nature of contact with the reptiles, contact only by older children and their hygiene practices.
At the Copenhagen Zoo, all reptile contact by kids is supervised, and students are required to wash their hands after touching a reptile. That's a great approach (as long as compliance is good), and the risks should be low for a short-term supervised activity such as this. High-risk kids, from an age standpoint, aren't involved since only 7-18 yr old students participate. So, the main group that would be of concern is immunocompromised children, who comprise a small but important subset of participants, and one that may slip by the established control measures since not all immunocompromised kids are readily identifiable. Unless schools know about all high-risk kids (and I'm far from convinced they do) and know that there are things these kids shouldn't do (e.g. have contact with reptiles), there are still some concerns. Those can be lessened further by ensuring that there is good communication between parents and the school, such that schools are really aware of any high-risk kids. That requires adequate knowledge on the part of the parents and the school, good communication in both directions and trust (since private health information is being disclosed). We have a long way to go to get there, and few people seem interested in starting those discussions.
Back to the Guelph paper photo. This wouldn't happen at the Copenhagen Zoo, since they apparently don't let 3-year-olds have contact with reptiles. I wasn't there so I don't know what was done in terms of hygiene, but even if this girl washed her hands after, there would still be a good chance that Salmonella was present on her skin or clothing based on how she handled the animal. This nature centre does some excellent work but I worry about the shows they offer for birthday parties. Their advertisement for this, with the "bring your cake and touch a snake" approach, and the picture of another young child with a snake draped around her raises concerns.
Reptile contact isn't inherently bad. There are just situations when it's high-risk and should be avoided. Beyond that, if it's going to be done, it must be done right. Unfortunately, more often than not, that's not the case.
As with most "pocket pets," guinea pigs don’t get a lot of attention in the scientific literature. As a result, we are limited in what we know about certain diseases in this species, and we tend to rely a lot on personal experience, small case studies and extrapolation from other species. It’s not that these sources of information are bad, they’re just not a replacement for larger, more controlled studies.
A recent study in the journal Mycoses (Kraemer et al. 2012) provides a rather comprehensive overview of ringworm (dermatophytosis) in these little fuzzy critters. The authors surveyed 74 owners of guinea pigs with ringworm and veterinarians. Here are some highlights from the results:
- 97% of ringworm infections were caused by Trichophyton mentagrophytes. Ringworm can be caused by a few different species of fungi, with a different organism, Microsporum canis, being most common in dogs and cats.
- 43% of the time, a new guinea pig was introduced into the household in the weeks preceding the onset of disease, and around one-third of affected guinea pigs had been in the household for less than 3 months. That’s not too surprising, since new animals are often a prime source of infectious diseases. It shows the importance of ensuring that new pets are examined carefully and are healthy before they are brought into the household. It’s certainly no guarantee that there won’t be problems, since healthy-appearing animals can be shedding various infectious agents, but it helps reduce the risk.
- Ringworm lesions were most common around the head. Hair loss was the most common sign, with scaling and crusting also common.
- Signs of ringworm were also present in other guinea pigs in the household in over one-third of cases.
- Various treatments were used and some animals weren’t specifically treated. In fact, 7/8 of the guinea pigs that did not receive specific anti-fungal therapy got better. It's known that ringworm can be self-limiting (meaning the animal will get better on its own over time). However, treatment can speed the process up and decrease the likelihood of transmission to other animals or people.
- In 24% of cases, people in the household also had signs of ringworm, on the head, neck and arms. Children were most commonly involved. That’s not too surprising since kids probably had more contact and closer contact with the animals than their parents.
While not a severe disease, ringworm is a problem because it’s highly transmissible. It can easily and quickly spread between animals, and between animals and people, and elimination of ringworm from a highly contamination household can be a major hassle. Presumably the risk of widespread environmental contamination is less with guinea pigs compared to dogs and cats because of their smaller size and tendency to be kept confined to cages most of the time.
Ringworm should be considered in any guinea pig that develops hair loss or other skin/hair problems. This is particularly true if it’s a new acquisition or if a new guinea pig has been introduced to the household recently.
If ringworm is suspected, a prompt visit to the veterinarian is in order. The guinea pig should be handled sparingly (or ideally, not at all) until the cause of the skin disease is identified. Close attention should be paid to hand hygiene, and even the use of gloves could be considered, although gloves aren’t a cure-all and people sometimes misuse gloves to such an extent that they actually increase the risk of spreading disease.
If a new guinea pig is obtained, it’s ideal to have it examined by a veterinarian before it comes into the household. I’m a realist and realize this is unlikely, but it’s ideal. In lieu of that, it’s important to get a guinea pig from a reputable source, to ensure that other guinea pigs from the same source don’t have skin disease, and to carefully examine the animal for skin lesions before it gets home. It’s also ideal to keep any new guinea pig in its own cage for a couple weeks to act as a quarantine period and allow for identification of any incubating diseases.
If owners of an infected guinea pig develop skin lesions, they should be examined by their physician, and make sure the physician knows they have been in contact with an infected animal.
Methicillin-resistant Staphylococcus aureus (MRSA) and other antibiotic-resistant bacteria are big problems. They account for millions of illnesses, thousands of deaths and billions of dollars in costs every year internationally. Antibiotic-resistance is a complex issue, but some people try to over-simplify (and under-analyse) the problem.
A recent article on Examiner.com is an example. Entitled "MRSA cases double in five years while natural solution is overlooked", the article - while providing very little real information - claims that essential oils are "unmatched tools in the fight against MRSA."
- It talks about the bacterial killing power of essential oils. That's certainly true. Many essential oils are potent antibacterial substances.
- It also claims that essential oils are "free of the side-effects common to antibiotics." That's not so true. In fact, essential oils can be quite toxic. Tea tree oil, one of the more popular essential oils, can cause a range of adverse effects, and I'm aware of a couple of dogs that have died from suspected tea tree oil toxicity. A study presented at the North American Dermatology Forum last fall (Valentine et al.) showed that while some essential oils were effective against resistant staphylococci, they also had damaging effects on canine skin cells. One oil had essentially no antibacterial effect but did a lot of damage to skin cells.
The antibacterial effects of essential oils might be useful, but only if they do no damage to the animal (or person) at the same time. The problem is these products are not technically sold as drugs, despite the fact that they are really marketed as drugs, so they bypass the requirement to demonstrate safety and effectiveness. If a product showed good antibacterial activity and no toxicity, it would be a potential option for the treatment of superficial infections, but in the absence of proper testing demonstrating safety, I wouldn't use an essential oil, as it may do more harm than good.
The Examiner.com article doesn't contain much useful information and is more of an infomercial than anything else. It highlights on particular company called Young Living Essential Oils. The author of the article also seems to be that company's "Product Training Program Manager," according to articles he's also written on the website. No conflict of interest there, obviously!
A complex problem like antimicrobial resistance requires complex solutions. Non-antimicrobial options are one part of this, which is why my lab has done work in this area. However, all-natural doesn't necessarily mean safe or effective, and we need to demand proper testing of such products. Too many companies take the cheap and easy way out and don't do any testing. While they may make money, their customers (and their pets) are the ones who can end up paying the price.
Sometimes, I get a little concerned when research papers get picked up by the press. It's not necessarily because the research is weak, it's just that results sometimes get overstated or misinterpreted when they work their way outside of scientific forums.
A paper published in the latest edition of the American Journal of Veterinary Research is one of those. The paper (Tsuchiya et al. 2012) describes a study that looked at the impact of interferon-alpha (used to stimulate the immune system) and enrofloxacin (an antibiotic) on body temperature and lung fluid white blood cell counts in 32 horses that were shipped for approximately 26 hours in commercial vans. Horses either received just interferon or interferon and enrofloxacin before being shipped.
- After shipping, 3 antibiotic-treated and 9 untreated horses developed fevers. That's actually not statistically significant, by my calculations, and it's quite strange that the authors didn't do that analysis (and that the reviewers didn't pick that up).
- Two antibiotic-treated and 7 untreated horses were treated with antibiotics after arrival because of concerns about infections. Again, that's not statistically significant and it's surprising (and concerning) no one pointed that out.
- Overall, the average temperature of horses in the treatment group was significantly lower after arrival, but the clinical relevance of that is questionable since it was only a 0.4 C difference. Further, it's hard to say what a temperature immediately after arrival really means, since that's pretty early for a bacterial infection to have developed.
- There were significant differences in tracheobroncial fluid (fluid collected from the airways) between the groups, with lower white blood cell counts in the treated group. That's an interesting finding and is consistent with less inflammation. What that means in terms of disease prevention is harder to say, but it's something worth investigating further.
- There does not appear to have been any difference between the two groups in the ultimate health status of the horses.
This study provides some interesting information to help us think about how, when and why infections and inflammation develop after shipping. Results suggest that antibiotics might be useful in certain situations, but many questions remain. Any antibiotic use runs some risk of complications such as antibiotic-associated diarrhea. It also increases the risk of antibiotic resistance (and ultimately more problems trying to treat disease). We have to remember these issues when considering these results. Further, while it is typically much better to prevent disease than treat it, in situations like this, it's hard to say whether mass prophylactic treatment is actually preferable to early treatment, since horses can be observed closely after arrival and treated when early signs of disease develop. Ultimately, it's still not even clear from these data whether pre-treatment with antibiotics actually does have a positive clinical effect.
It's important to remember what this study tells us, and what it doesn't. Despite what some lay articles that have picked up the story say, it doesn't mean that antibiotics are broadly useful for keeping shipped horses healthy. The authors address this by stating "The use of enrofloxacin raises concerns regarding the emergence of antimicrobial-resistant bacteria, and it is important that antimicrobials such as enrofloxacin are not used inappropriately. The guidelines for enrofloxacin use in the Japan Racing Association’s medical office require that it is only administered as prophylaxis against transportation-associated fever when the duration of transportation is expected to be ≥ 20 hours and the horse has had clinical signs of transportation-associated fever before or is considered to be at risk for developing transportation-associated fever (eg, if the horse has undergone laryngoplasty or has a history of pneumonia)."
Regarding the big picture, however, this should make us think again about how we manage horses. Antibiotics should never be used as a crutch in place of good management. In a situation like this, where 19% of horses treated with interferon and enrofloxacin and 56% of horses treated with interferon alone get sick, something's wrong. Antibiotics may be an easy way to try to reduce the likelihood of disease in some situations, but that doesn't mean it's a good idea. Considering the number of horses that get sick (and die) every year from shipping-associated illness, maybe we need to rethink how they are transported. Is lack of antibiotics the problem, or is it how (and how long) horses are shipped? Maybe long, interrupted trips aren't a good idea, antibiotics or not.
I get a lot of emails about this blog. Some are complementary, some... well... not so much.
When it comes to the latter group, the most common (and often the most grammatically-challenged) group is raw meat feeders. They're a constant source of interesting comments about my intelligence and other aspects of my life. Some actually provide well-written explanations of why they do what they do and I've had some good discussions with a few. Others just like to call me stupid and move on. The guy who provides treatment recommendations for dogs based on fish antibiotics (and his buddies) was another interesting one. The dodgy equine protozoal myelitis clinical trial person (and her friends) was another (she also wrote to my Dean... that's another story). The list goes on.
The latest group has been people upset that I have concerns about reptiles in schools. It seems that a post I wrote a while ago about a school reptile club ended up on a reptile website, whose members are now inundating me with emails. While I appreciate the fact that they are reptile enthusiasts and like their pets, they're missing the big picture.
Yes, reptiles can be good pets, in certain situations. I actually like reptiles. I used to own a few, and the first patient I treated in practice was a reptile.
I've also spoken with people whose children have acquired Salmonella from a reptile. I've read numerous papers about kids that died from Salmonella from a reptile, and I think I've yet to meet an infectious diseases physician who doesn't almost immediately launch into reptile-Salmonella stories when they hear what I do.
The fact is, reptile exposure accounts for a very disproportionate number of Salmonella infections in people, and kids bear the brunt of this. That's why the CDC and various other groups say that reptiles shouldn't be in households with young kids (or the elderly, pregnant women or people with compromised immune systems). The same applies for schools and day cares, where young kids are present, parental knowledge of the exposure is often non-existent, and basic infection control practices are spotty, at best.
No one is saying people shouldn't keep reptiles as pets. However, to me, the evidence is clear that certain people shouldn't have reptiles as pets or be in contact with them. Adults can decide to do things that compromise their health. Adults shouldn't make decisions that compromise the health of their kids or kids for whom they are responsible. Ensuring high-risk children stay away from high-risk animals like reptiles is part of that.
In response to Salmonella outbreaks linked to these critters, their popularity as pets for young kids, and efforts to ban them in some areas, we've developed an info sheet regarding African Dwarf Frogs. As with our other info sheets, it discusses the good and bad points of owning these little guys, things to consider when deciding whether to get one, and measures to reduce the risk of infection.
This info sheet, along with many others, can be found on the Worms & Germs Resources - Pets page in the Information Sheets for Pet Owners section.
The old saying is "when you hear hoof-steps, think horses, not zebras." In a medical context, it means common things occur commonly, so don't start off thinking about wild and bizarre conditions before you've ruled out the usual suspects. Along that line, when I hear "rabies," I think "bats, raccoons, dogs, cats, foxes..." I don't think about... zebras.
Considering there aren't that many zebras in Ontario, and even in places where there are zebras, most people don't have a lot of contact with them, it makes sense that zebras don't typically make the rabies suspect list. But that doesn't mean zebras can't get rabies.
A Letter in Emerging Infectious Diseases (Lankau et al, 2012) describes one such unusual scenario. In January of 2011, an orphaned zebra foal was taken in by a safari lodge (that's probably not too unusual of an occurrence), and not surprisingly, tourists were allowed to handle and feed the foal. Unfortunately, the foal was bitten by a dog at the end of July. The dog was suspected of being rabid but it doesn't seem like any changes were made to how the baby zebra was handed. Unfortunately, the foal died at the end of August and rabies was confirmed. Lodge staff tried to contact people who had visited during the July-August time period, mainly through emails to travel-booking agents who (it was hoped) forwarded the information to travelers.
Several US travelers contacted CDC after getting the email and their risk of rabies exposure was investigated.
- CDC obtained names of 243 travelers who were at the lodge, 136 of whom were from the US.
- They worked with the assumption that the outside window for rabies virus shedding by the zebra was a 14 day period leading up to its death. Seventy-seven (57%) of the US visitors had been there during that period.
- Twenty-eight of those visitors had already started post-exposure treatment for rabies. None of those individuals had high-risk exposures, 2 had moderate-risk exposure while the rest had low or no-risk exposures, so treatment would not have been recommended for most of them. That's probably because the information went from the lodge to travel agents to travelers, and then to the peoples' general physicians (who are generally less well versed in rabies exposure issues) rather than through public health.
- The cost of rabies post-exposure treatment is at least $4000/person in the US (although I know of cases where the cost was much higher), so at least $100 000 was wasted, in addition to stress and other factors.
Some take home messages
- People need to think about animal contacts when on vacation. Travelers that go to rabies-endemic areas need to pay particular attention to avoid high-risk contact with animals.
- Facilities that allow animal contact need to protect the public. Rabies vaccination of this foal might have prevented its infection and the subsequent human exposures.
- If an animal has been attacked by a rabid animal, don't let people come into contact with it!
- Rabies exposure is a medical urgency, not an emergency. There's time to make sure things get done right, and public health personnel should be involved in discussions of exposure and treatment.
The outbreak stretched over a long period of time, from 2007-2009, and involved a strain of Salmonella called Salmonella Java. During the course of the investigation, 75 people with S. Java infection were identified, although there were probably many more infected since diagnosed cases are usually the minority of the true total.
Individuals affected ranged in age from 1 month to 60 years, but the median age was only 2 years, which means the majority were very young children. The investigation started to focus on playgrounds and ultimately 207 sand samples were collected from 39 locations. Thirty-five isolates of S. Java were found, all from 6 playgrounds. These playgrounds had all received sand from the same depot over the preceding year, but Salmonella wasn't found in samples from the depot.
To try to find a source, they started testing critters living in the area of parks, and found S. Java in 34 of 261 animals, mainly from long-nosed bandicoots (a marsupial indigenous to Australia).
It's possible that this Salmonella strain is widely present in bandicoots (and other critters) in the area. I don't know their defecation habits, but if they have a preference for pooping in sandboxes (like cats do), they could be contaminating play areas. The other possibility is that the sand was contaminated from some other source and the bandicoots were infected from the sand just like the people. There's not really any easy way to figure that out.
Sandboxes have been associated with various disease outbreaks, but the overall risk is low and it's certainly not a reason to keep kids away from them. Some things that can be done to reduce the risk of potential disease transmission from things in the sand include:
- Supervising kids to prevent them from sticking things in their mouths.
- Making sure they don't eat or drink in the sandbox/playground.
- Making sure they wash their hands after playing in the sand.
- Covering the sandbox whenever it's feasible (not always an option but good if it can be done) to help prevent animals from defecating in the sand.
More information about sandboxes and potential disease risks can be found on the Worms & Germs Resources - Pets page.
Image: Long-nosed bandicoot from Eastern Australia (Perameles nasuta)(click image for source)
Let me say it again... yes, dogs can get salmonellosis.
...and in French, oui, les chiens peuvent devenir malades de salmonellose (hope that's close)
...and in Swahili, ndiyo, mbwa anaweza kuwa na wagonjwa salmonellosis (thank Google Translate for that one).
What prompted my recurrent 'yes dogs can get Salmonella rant'? Another fluff piece on feeding dogs raw meat diets, this time in the Globe and Mail (a national paper in Canada).
The "dogs can get Salmonella" rant doesn't actually stem from the newspaper, since the article didn't even bother to get into potential infectious disease or nutritional deficiency concerns with these diets (in-depth reporting it was not). Rather, the rant is in response to comments on the paper's website that include the typical garbage that dogs are not susceptible to Salmonella because of their short and acidic intestinal tract. It's a fallacy that's widely distributed on the internet on raw pet food sites, and it's wrong (although ironically enough, many of these same sites also talk about how dogs get sick from Salmonella from commercial foods).
To set the record straight:
- Dogs can get Salmonella.
- Most often they don't get very sick, but sometimes they die.
- Ingesting Salmonella from food or other environmental exposures is the source.
- The more Salmonella a dog eats, the greater the risk of disease.
- Raw meat is often contaminated with Salmonella.
Now that I've gotten that off my chest, I'll get back to the article. It's written by someone who feeds her dog raw meat. I have no major problems with that for the average dog and average person. It increases the risk of salmonellosis in the dog and in the family (and potentially anyone or anything in contact with the dog or its poop), but the risk of infection for your average, healthy dog and person is relatively low. It's a bigger issue when there are high risk people or animals in the house, and human and pet infections from feeding raw meat certainly do occur.
I'd rather people not feed raw (or at least make sure they feed high pressure pasteurized raw meat) but I'm a realist and I realize some people are going to do it anyway. I therefore focus on trying to educate people about situations when they really shouldn't feed raw meat (e.g. high risk dog or person in the household, young growing animals) and what to do to decrease the risk of transmission of Salmonella. More information of this kind is available on the info sheet that can be found on the Worms & Germs Resources - Pets page).
Anyway, back to the article (I really mean it this time). The article includes some interesting information, particularly the very high cost of feeding a raw diet compared to commercial dry or canned foods. However, it also contains some of the same drivel that's found in most of these articles. For example:
"'Dogs don’t have microwaves or grocery stores in the wild,' she says with a laugh, adding that she believes a dog that eats raw will lead a longer, healthier life than one fed traditional dog food."
- They also don't necessarily live long, happy and healthy lives in the wild. Today's domestic dog is long removed from the mystical wild dog. My dog Meg wouldn't make it very far in the wild, unless there are dog food trees somewhere that I don't know about.
"'On a kibble diet, her dogs were 'overweight, with no energy - scratching all the time from all the allergies,' she says. 'These were our fat, miserable, lethargic dogs.'"
- Less food, more exercise and good veterinary care could probably have taken care of that too.
As I said above, people are free to make their own choices, but they should get informed, and they need to go beyond raw food company websites and support groups. They need to think about potential benefits, potential risks, cost, hassle and other factors to determine if it's right for them and their dog. Getting real information and critically assessing the information that's out there are critical steps.
Q-fever, a serious disease caused by the bacterium Coxiella burnetii, is an important concern at petting zoos because small ruminants (sheep and goats) are commonly present at these events and they are the major source of this pathogen. The risk is greatest around adult animal at the time of birthing, and around the new lambs and kids (baby goats), because this is when large numbers of highly infectious Coxiella can be shed. That’s one of the reasons why pregnant small ruminants shouldn’t be part of any petting zoo, but unfortunately this particular recommendation is widely disregarded.
Other than petting zoos, the general public can also have contact with small ruminants through various other routes. An outbreak of Q-fever in the Netherlands (a country with serious Q-fever problems) was reported in association with one of these atypical events, namely "lamb viewing days" on a farm (Whelan et al, Epi Infect 2012).
This farm was open to the public every year during lambing season, and attracted about 12000 visitors from the area annually. Visitors could watch lambs being born (if the timing was right) and interact with young lambs. After finding a cluster of Q-fever cases in the region, an investigation ensued, which compared people who were diagnosed with Q-fever in the region to a group of people without Q-fever. Here are some of the highlights:
- 21% of people with Q-fever reported visiting the farm compared to just 1% of controls.
- When various other factors were controlled in the analysis, having visited the farm meant someone was 43.3 times as likely to have Q-fever compared to someone who didn’t visit the farm.
- Coxiella burnetii was identified in numerous sheep, as well as from 7 of 8 air samples collected on the farm. (Coxiella is a very small, hardy organism that can resist drying, and it can therefore often be found in the dust in the air in areas that have a lot of environmental contamination, like pens where goats and sheep give birth.)
- Specific contacts (e.g. holding a lamb, witnessing a birth) were not identified as risk factors, but the small sample size of people that reported what types of contact they had may have limited the ability to detect a difference.
Visiting farms and having contact with farm animals shouldn’t necessarily be considered a high-risk behaviour. In fact, in some ways it’s a good thing. Greater contact between people and animals and a better understanding of farm animals can be very beneficial. However, we’ve known for a long time that some situations pose an increased and unnecessarily high risk. People organizing farm encounters or petting zoos need to take some basic precautions to reduce the risk to visitors. These are pretty simple and can be done without significantly affecting the visitors' experience. Visitors also need to take some responsibility themselves and follow recommendations, like practicing good hand hygiene and keeping food and drink out of animal areas (just to name a couple). Additionally, the more visitors know about risks and preventive measures, the more they can pressure facilities into doing things right. Public health personnel can work hard to try to improve petting zoos and other events, but nothing will change things quicker than an informed public withholding their money from places that put them at unnecessary risk.
I've had a run on questions about survival of rabies virus outside the body. The topic comes up periodically with respect to touching roadkill or veterinary clinic personnel working with animals that have been attacked by an unknown animal. The case of three people who developed rabies after taking care of a sheep that had been attacked by a rabid animal, probably through contact with saliva from the rabid animal on the sheep's coat coming into contact with broken skin on their hands, shows the potential risk. An important part of assessing the risk is understanding how long the virus lives outside the body.
Some viruses are very hardy and can live for weeks or even years outside the body. Parvovirus and norovirus are classic examples of this type. Some viruses, like HIV, die very quickly in the environment. Part of this relates to whether they are "enveloped" or "non-enveloped" viruses. Enveloped viruses have a coating that is susceptible to damage from environmental effects, disinfectants and other challenges. Damaging this coating kills the virus. Non-enveloped viruses don't have that susceptible coating and that is in part why they are so much hardier.
Fortunately, rabies is an enveloped virus, and it doesn't like being outside of a mammal's body. Data on rabies virus survival are pretty limited, since it's not an easy thing to assess. To look at rabies virus survival, you have to grow the virus, expose it to different environmental conditions, then see if it's still able to infect a mammal or a tissue culture. We can do this easily with bacteria, but growing viruses is more work, especially a dangerous virus such as rabies virus.
I can only find one study that has looked at rabies virus survival (and I can only read the abstract since the rest of the paper is in Czech). The study (Matouch et al, Vet Med (Praha) 1987) involved testing of rabies virus from the salivary gland of a naturally infected fox. They exposed the virus to different conditions and used two methods to look at the infectivity of the virus.
- When the virus was spread in a thin layer onto surfaces like glass, metal or leaves, the longest survival was 144 hours at 5 degrees C (that's ~ 41F).
- At 20C (68F), the virus was infective for 24h on glass and leaves and 48h on metal.
- At 30C (86F), the virus didn't last long, being inactivated within 1.5h with exposure to sunlight and 20h without sunlight.
So, rabies virus can survive for a while outside the body. Temperature, humidity, sunlight exposure and surface type all probably play important roles, but in any particular situation you can never make a very accurate prediction of the virus's survival beyond "it will survive for a while, but not very long."
From a practical standpoint, it just reinforces some common themes:
- People should avoid contact with dead or injured animals.
- Veterinary personnel or pet owners dealing with a pet that has been attacked by another animal should wear gloves, wash their hands and take particular care if they have damaged skin.
- People who are at higher than normal risk of being exposed to potentially rabies-contaminated surfaces should be vaccinated against rabies.
Image: Schematic diagram of a rabies virus showing the outer viral envelope (source: CDC Public Health Image Library)
I love my cats. But sometimes when Bonnie and Clyde are living up to their names, puking up hair balls twice a day, peeing on the guest bed (yes, contrary to popular belief even vets can't stop their own cats from doing this sometimes), caterwauling at 3 AM, or begging for food all afternoon, they do make me c-r-a-z-y crazy - but they're not making me suicidal.
In yet another example of how the media will present study results in the manner that will sell the most newspapers or magazines, rather than the way that helps people interpret the results in a logical manner, comes an article entitled "Is Your Cat Hosting a Human Suicide Parasite?" The article talks about a study recently published in the Archives of General Psychiatry (Pedersen et al. 2012) which looked at a cohort of 45 788 women in Denmark who gave birth between 1992-1995, and found a statistically significant association between self-directed violence (including suicide attempts) in these women and their antibody titre to Toxoplasma gondii at the time of birth. The risk in seropositive women was 1.53 times greater than the risk in seronegative women.
Toxoplasma gondii is a parasite that is shed in the feces of cats, which are the parasites definitive host. Most house cats only ever shed significant amounts of the parasite the first time they're exposed to the parasite (typically when they're young). Depending on where people live and various cultural practices, transmission of the parasite from scooping out litterboxes may actually be relatively uncommon compared to other possible sources including exposure from soil (e.g. working in the garden and then not washing one's hands), eating unwashed vegetables, or eating some types of undercooked meat.
The most glaring limitation of the Pedersen study is that they didn't control for any other factors that may have resulted in the women who committed acts of self-directed violence being more likely to be seropositive for Toxoplasma than others. For example, women with mental illness may be less likely to practice good hand hygiene (one of the most important factors for reducing the risk of parasite transmission), and therefore more likely to be exposed to Toxoplasma, or there may be other factors about their health or their lifestyle that make them more prone to infection. The point is the authors only found an association in a specific subset of the population (Danish women who had given birth to at least on child). This does not mean that the relationship is causative - they can't say that Toxoplasma infection makes people more prone to self-directed violence, only that women - in this particular group - who were seropositive for the parasite were also at increased risk for this kind of behaviour. It's a somewhat subtle but very important difference. The authors of the study clearly acknowledge the limitations of their work, but the news article does not do quite as good a job of pointing this out, until right at the very end where it does finally get mentioned.
Does Toxoplasma infection cause behavioural changes in rats that may make them more likely to wander into a cat's territory and be eaten? According to an experimental study it can, and it does make a certain amount of ecological sense that the parasite could have an effect on its intermediate host (the rat) that makes it more likely to be able to continue its life cycle (via being eaten by a cat) by reducing fear in the rat. Could infection of the brain in humans cause subtle behavioural changes? I can't deny the possibility, but humans are not rats and I would be very wary of extrapolating results from one species to the other. But is this parasite likely to "drive our brains off the highway" as the news article says? I'm not ready to buy that, certainly not based on this study. As the authors clearly state in the first line of the paper "Suicide is a tragic multifactorial outcome of mental illness, with complex biopsychosocial underpinning..." There are so many things that contribute to such an unfortunate outcome that a lot more work is needed before anyone can justifiably blame a "suicide parasite" in cats.
Whether you believe Toxoplasma infection can result in behavioural changes in people or not, there are some very simple steps everyone can take to help decrease the risk of becoming infected with this parasite regardless. These are particularly important for individuals who are immunosuppressed and women who are pregnant, because it is very well established that toxoplasmosis in these high-risk individuals certainly can have severe repercusions to either the individual or the unborn fetus. However, it is by no means necessary for such individuals to get rid of their cats if they take these simple precautions:
- Clean your cat’s litter box every day. The oocysts shed in cat feces usually take about 24 hours to become infective once they’ve been passed, so daily cleaning helps remove them before they reach this stage.
- Always wash your hands with soap and water after cleaning your cat’s litter box, after working in the garden or in any soil, and after handling raw meat.
- Keep your cat indoors. Outdoor cats are more likely to be exposed to Toxoplasma and shed oocysts in their stool.
- Keep sandboxes covered so outdoor cats don’t contaminate them with stool.
- Cook all meat, especially pork, lamb, mutton and wild game, to an internal temperature of 67ºC/153ºF or higher.
More information about Toxoplasma can be found on the info sheet on the Worms & Germs Resources page.
When I'm giving talks about zoonotic diseaes to people in the human healthcare field, I sometimes mention tuberculosis (TB) as an example of a serious human disease with poorly defined (but theoretically important) risks of transmission between people and pets. TB is a very important disease of increasing of concern because of its resurgence in many areas and the spread of drug-resistant strains.
We don't know much about TB and pets. There are some older studies that provide conflicting information, suggesting that Mycobacterium tuberculosis, the bacterium that causes TB, can be commonly or rarely isolated from dogs owned by TB patients.
A recent study from South Africa (Parsons et al. Research in Veterinary Science 2012) provides more information. The study involved two main components:
- For the first component, they examined 100 stray dogs in Cape Town, South Africa, for evidence of TB. The dogs were being euthanized for population control purposes so the researchers were able to do necropsies (post-mortem exams) to look for the bacterium and signs of disease that may not have been outwardly apparent. They isolated the bacterium from 4% of the dogs, with only one of those having any signs of disease. That shows that TB is present in dogs in the area, albeit at a low rate. The fact that 3 of 4 TB-positive dogs had no evidence of disease is both good and bad. It's good for the dog's health that illness doesn't always occur (just like in people), but it also means that apparently healthy dogs can be carrying this concerning bacterium. The risk of transmission from healthy carriers isn't known. It's probably rather low since close and prolonged contact are required to transmit TB between people, and healthy carrier dogs are probably not shedding many TB bacteria through their respiratory tract. Greater concerns are probably present in dogs with TB infection of the lungs who are coughing and spewing TB bacteria into the air.
- The second component of the study involved testing of 24 dogs living with people with TB. They used two different tests: the TB skin test (a test that's commonly used in people but one that's been typically considered useless in dogs) and an interferon gamma release assay (IGRA)(a test more commonly used now in humans). They concluded (not surprisingly) that the skin test was pretty useless, but their data suggest the IGRA may be a good test for dogs. 50% of dogs in those households had evidence of TB exposure through IGRA, consistent with one older study that indicated transmission of TB from people to pets may be common.
What are the implications of all this?
For the average person and pet, not much. TB transmission requires close and prolonged contact with an infected individual. You don't get it walking down the street behind someone with TB.
The concern is in situations when people with TB may have contact with pets - the same concern as in situations when people with TB may have contact with other people. The potential for transmission is something to pay attention to in households where there is an infected person, or in populations where there may be high TB rates and common pet contact (e.g. some homeless populations).
Results of this study should be a reminder that when considering who's potentially been exposed to a person with TB and making plans to reduce the risk of transmission, you need to consider all individuals - human and animal - with which the person has contact. Therefore, measures taken by people to avoid transmission of TB to other people should be equally applied to reducing transmission to pets. Pet exposure should always be considered, particularly when dealing with multidrug-resistant (MDR) or extensively drug-resistant (XDR) TB, since such strains are huge concerns in people and we don't want to create canine or feline vectors of these strains. The study results also indicate that pets owned by TB patients may be at increased risk of disease from TB, not just at risk of being infected and harbouring the bug. Therefore, knowing that a pet has had close and prolonged contact with a person with TB is relevant to veterinarians when evaluating sick animals.
Markham, Ontario's city council has passed a bylaw prohibiting the keeping of African Dwarf frogs. While in reality more of a ban on the sale of frogs in the city (since I doubt there will be any effort to search for contraband frogs in households), and perhaps of somewhat limited impact because of the availability of the potentially Salmonella-laden critters in neighbouring areas, not to mention the common practice of pet retailers flouting laws like this, it's nonetheless a step that will hopefully reduce the number of these animals in households.
Why the fuss about African Dwarf frogs?
- Mainly, it's because of the risk of transmission of Salmonella from these frogs to people. Large numbers of Salmonella infections have been linked to these frogs internationally, and the risks are amplified with pets like this that are marketed toward young kids (especially as pets to keep in their bedrooms) and for schools and childcare facilities, because children are one of the highest risk groups for developing salmonellosis.
- The other important issue is animal welfare, since these frogs are often sold in unsuitable habitats and have a fairly limited lifespan in captivity.
Not surprisingly, the owner of the US company that is one of the main distributors of these animals is unhappy with the decision. It's hard to be sympathetic given the fact that they essentially ignore the risks these animals pose to people, at least in the materials they present to the public. Despite the fact that they are marketing what is considered a high-risk animal as a pet, there's little effort put into providing information about that risk or risk mitigation. Looking at their promotional materials, I can find lots of information about how to care for the aquarium. Yet, none of it mentions Salmonella. There's no statement about keeping young kids away from frogs. There's no mention of washing hands after contact with frogs or their environment, or that aquarium water shouldn't be dumped down bathroom or kitchen sinks... or any other basic, relevant infection control practices. They do have some CDC information on their website if you look around, which is better than nothing, but it needs to be more prominent. Everyone that purchases one of these frogs should get a clear information sheet that explains the risk of Salmonella transmission and how to avoid getting sick. Yes, it puts a bit of a damper on the new pet, but a lot less than being hospitalized.
Back in Markham, it's hard to say whether the ban will have an impact on frog ownership because of the ability to buy frogs a few minutes away in neighbouring municipalities, and the likely lack of any real enforcement effort. However, it's a start and if nothing else, and publicity associated with the ban may help educate people. African Dwarf frogs that are already in households are exempt and can live out their natural (albeit often short) lifespans, but people can't replace them when they are gone.
More information about Salmonella can be found on the Worms & Germs Resources - Pets page. We don't have a dwarf frog info sheet (it's coming) but most of the information on the Reptiles info sheet equally apply to frogs.
Travel always carries a risk of infectious diseases. More people are paying attention to their health and going to travel clinics to find out about these risks and what preventive measures they can take. They still constitute only a minority of travelers, but it’s an improvement. There aren’t travel clinics for pets, so travelers thinking about pets and infectious diseases need to rely on sources like their regular veterinarians and government websites.
Unfortunately, that doesn’t always result in good information, as shown in a study recently published in Zoonoses and Public Health (Davidson et al 2012). For the study, the authors called veterinary clinics in eight European countries (Austria, Belgium, Finland, France, Germany, Sweden, Switzerland and the UK) and asked them about taking a dog to Norway. They also called clinics in Norway and asked about bringing a dog to the country from an unspecified location in Europe. Calling was done not as a research survey but by a person pretending to be a pet owner.
The study focused on two main pathogens, Echinococcus multilocularis (a tapeworm that is present in some parts of Europe but not others, and one that is both an animal and public health concern) and rabies. Only 9% of clinics provided accurate information about these two problems. Some clinics (58%) referred people to government sites that have good information, but unfortunately 13% of clinics referred people to websites or government agencies that provided incorrect or incomplete information. When information from websites is included, people received correct advice 62% of the time. Not bad but not great.
Among the bad advice that was given (or important information that was not given):
- Failure to tell people about the requirement for tapeworm treatment after arrival.
- Incorrect tapeworm treatment information.
- No mention of rabies titre testing.
- False information that pets traveling to Norway don’t require tapeworm treatment.
This shouldn’t be taken as indicating that veterinary clinics aren’t competent. Travel medicine certainly isn’t something I was taught in vet school. Most veterinarians (understandably) don’t spend much time reading about problems that only occur in other geographic regions, since there’s enough other new information on which they must stay current. So, they may not have answers at the tip of their tongues when asked a question. Trying to get good information by random phone calls or as an aside during a veterinary appointment might not be the best approach. However, since we have a surprisingly mobile pet population, with pets traveling with owners to many different regions, it’s an important area for veterinarians to think about, from two standpoints:
1) Counseling people who are traveling: As was the focus here, it’s important for people to know about disease risks and regulatory requirements for places to which they travel. Specific preventive measures (e.g. vaccination, deworming) that are not needed at home may be indicated when traveling.
2) Diagnosing disease in returning animals: It’s easy to miss travel-associated diseases, and that can lead to bad outcomes. If veterinarians don’t ask whether a pet has traveled, they won’t realize that there might be some other diseases to consider. If they don’t know about disease concerns in other regions or (perhaps more importantly) don’t have ready access to good information about disease risks in other regions (e.g. accurate websites), they might not consider important diseases even if they ask about travel history.
This study highlights a few of the current gaps in the system, involving background knowledge, client communications and variable accuracy of electronic sources. People who are traveling with pets (or acquiring pets from abroad) should have a thorough discussion with their veterinarian (not just a casual call to the veterinary clinic, during which information may come from or through lay staff) about the situation, and they need to do their own homework. It's probably best to make sure the clinic knows that there will be travel questions in advance, so mentioning it at the time of booking the appointment might help.
As the authors of this research state “An accessible, centralized, easy to use website, that is updated by a central regulating agency and applies to all countries, would allow veterinarians to refer pet owners to one site for further information regardless of which country they are travelling from and going to.”
That's the ideal situation. Given the minimal attention that governments pay to pet animals, it's probably going to have to be an government-independent, collaborative venture. We've had some discussions about this in the past and it would be great to do, but the logistics are a bit daunting. Maybe it's time to resurrect those discussions.
This time of year, it's very common around here to see young raccoons wandering about. It's also still pretty common to hear about people keeping a litter of baby raccoons in their house. I can understand the appeal - they're cute and entertaining. However, in addition to being illegal in many regions, handling young raccoons also poses a risk of exposure to a variety of infectious diseases.
Chief among the infectious disease risks of handling young raccoons is rabies, as a Walker County, Alabama, family found out. Two baby racoons were found in someone's attic, and another two littermates were found a little while later. The person who found them gave two each to two separate people. As is often the case, they were handled by many different individuals before one of the raccoon kits was found to be rabid. Now more than 20 people are facing post-exposure treatment. It's one of the larger reported exposures from a single rabid raccoon, but it's far from unprecedented.
Beyond the obvious public health concern, this situation demonstrates another possible issue. Rabies is sporadically distributed in some regions, and moving wild animals around leads to the potential for dissemination of rabies, as well as other infectious diseases. Raccoon rabies is present in the area where the baby raccoons were found, but has not been found in Walker County, even though it's not far away. If the rabid raccoon had escaped (or was released), it could have potentially spread rabies into an area where it's currently not well established, thereby increasing the risk of exposure to everyone (animals and people) in the county.
As mentioned above, it's also illegal to harbour wildlife in many regions if you are not a licensed rehabilitation facility. While getting fined seems to be uncommon, four people in this incident have been charged with unlawful possession of a protected animal. Just one more reason not to do this.
While baby raccoons may have some appeal, as Alabama's state veterinarian Dee Jones says, "...people just need to stay away from them."
Case 1: A veterinary technician was infected through contact of broken skin with saliva. The man had scratched skin on his hand, which he put in the mouth of a rabid cow during a procedure. This situation brings to mind several important points:
- All veterinary personnel in rabies endemic areas should be vaccinated against rabies. I don't know about rabies vaccine supply issues in Iran, and that might be a limiting factor, but there are still too many unprotected veterinary personnel in most countries.
- This person seemed to have known that rabies was suspected in the cow, but apparently didn't consider this kind of contact to constitute exposure, so he didn't seek treatment. Once he started to get sick, he actually suspected rabies well before his physicians, so he obviously was well informed about the disease.
- There is a need to consider rabies when evaluating any animal, to use proper barriers (e.g. gloves) when handling rabies suspects, to test for rabies when there is any chance an animal has died of the disease, and to get post-exposure treatment if there has been a potential exposure to the virus. These steps aren't always straightforward, especially since signs of rabies in cattle can be quite variable.
Cases 2-4: There were three members of the same family tending a herd of sheep and one of the sheep was attacked by a rabid wolf. The three individuals were believed to have been exposed while tending to the sheep, since their hands were scratched in the process and it was thought that rabies virus-laden saliva still on the sheep's wounds got into those scratches.
- This one surprises me. It's not a route of rabies exposure we typically consider, since rabies virus is quite labile (i.e. rabies virus does not survive long once it's exposed to the environment, even on the outside surface of a wound). I guess it makes sense if the three individuals were scratched and exposed to saliva right after the attack. I don't think this indicates broad risk to people who take care of animals that have been attacked, but it's something to think about when dealing with an animal that has just been attacked. It's another reason that we should be wearing gloves when handing open wounds (typically, gloves are recommended to protect the individual with the wound, but it goes both ways) and take care to perform proper hand hygiene. However, both of these are hard to do while tending a flock of sheep in rural Iran.
Case 5-6: These individuals were infected through corneal transplants from the same donor. The donor was reported to have died from "food poisoning," although undiagnosed rabies must have been the true cause (unless you have the very unlikely situation that the person was infected but coincidentally died of food poisoning just before signs of rabies developed).
- Corneal transplants have been associated with transmission of various diseases, and transplant-associated infections of many kinds have caused many deaths. That's why there are strict protocols for screening donors, both in terms of what they died of and what testing is required. I'm surprised they'd use tissues from someone who died with an inexact diagnosis such as "food poisoning," especially since that can have an infectious cause.
Overall, these non-bite associated cases account for a small minority of human rabies cases that occur every year, but unusual routes of exposure need to be considered in any case.
Israel's Health Ministry is recommending rabies vaccination for people traveling to India.This seems to be mainly in response to the recent high-profile case of an English woman who died of rabies acquired from a dog in India. While it was high-profile, that certainly wasn't the only travel-associated rabies infection in the past year. Rabies exposure is a serious concern for people who might encounter dogs (intentionally or accidentally) while traveling in countries with endemic canine rabies. The news report states that rabies vaccine is available at clinics in Israel for would-be travelers, however it doesn't say whether the cost of vaccination is covered by the government. Human rabies vaccination is quite expensive, which may be a limiting factor when it comes to convincing travelers to get vaccinated, unless the government foots some or all of the cost.
Raising awareness of the problem with rabies in some developing countries is good. Most people don't really think about travel-associated disease (beyond the ubiquitous diarrhea that comes with travel to some areas), particularly something like rabies. In addition to focusing on vaccination, however, it would be even better to see a broader initiative to remind people to avoid contact with stray dogs (and other animals) and to make sure they get proper medical care after potential rabies exposure. Also, while India is certainly a hotbed of canine rabies, it's important to remember that there are many other countries where dog rabies is a major problem, and similar measures need to be taken for travel to these places too.
A surprisingly large number of people get sick and die every year from diseases acquired during travel. Travelers need to be aware of disease risks in areas they visit, know what preventive measures they should take and how to get proper medical care in any region they visit. While thinking about this might put a damper on vacation planning, it's worth the effort. When it comes to rabies, unless you know that a region is officially (and truly) rabies-free, assume that any encounter with a wild mammal, especially a stray dog, could be a source of rabies exposure. You don't want to travel in a bubble and stick to sterile locales, but you also don't want to come down with a fatal disease when some basic precautions could have prevented it.
While rabies is classically transmitted from animals to people by bites, any situation that allows saliva from an infected animal to get past the body's protective skin barrier can result in infection. Graeme Anderson, a 29-year-old South African canoeist, recently died after contracting rabies from a sick dog for which he was caring. There was no history of a bite, but the dog had licked damaged skin on the man's hands, allowing the virus to enter the body.
Any contact with animals showing signs consistent with rabies needs to be investigated. Licks over damaged skin (or mucous membranes like the mouth) are classified by the World Health Organization as having the same level ("severe") risk of rabies exposure as bites, and post-exposure prophylaxis is indicated. Bites are the main source of rabies transmission, but not the only source, the fact of which situations like this remind us.
Plague cases tend to get a lot of press. The fact that this disease killed a large percentage of the human population in a few different pandemics (albeit centuries ago for the most part) probably plays a role in that. Despite the impression by some that it's just a historical disease, plague is alive and well in certain parts of the world, including parts of the US, and infects a few thousand people every year.
Plague is caused by the bacterium Yersinia pestis, which lives in various wild rodents and is circulated by fleas. Transmission to people historically has been via fleas that jump from rats to people. However, plague isn't just a rat-human disease, as it can infect other animal species. Among domestic animals, cats seem to be most commonly infected, probably because of exposure while hunting.
The problem with plague and pets has been shown once again a case of plague in an Oregon man who likely picked up the infection from his cat. (Oregon is outside of the main range of plague in the US, where the disease is most common in the southwest). The man was bitten by the cat while retrieving a dried, decayed mouse carcass from its mouth. He developed septicemic plague (infection of the bloodstream), and then pneumonic plague (infection of the lungs), which is the worst case scenario. At last report, he was in critical condition and the prognosis for survival is probably guarded.
There's no mention of the cat's health. Most cases of cat-human plague occur in people taking care of sick cats (especially veterinarians). If a person is infected by a cat bite, I would expect the cat to have been sick with plague, although transmission has been reported from apparently healthy cats. Some other possible routes may need to be considered. If the cat in this case was exposed to plague, then plague's obviously in wildlife in the area, so you have to consider that the infected man might have been bitten by an infected flea (that came directly from an infected wild animal or that the cat tracked in) or from direct contact with wildlife, especially if his house had a rodent infestation.
Regardless, it's important for people in plague-endemic (and neighbouring) areas to be aware of plague and take measures to reduce the risk of exposure for themselves and their pets, such as:
- Avoid contact with wild rodents (and wildlife in general, since larger wildlife species can also be infected).
- Keep cats inside.
- Don't let pets with outdoor access roam unobserved, where they might be more likely to encounter wildlife.
- Have a flea control program for pets.
- Address any animal/household flea infestations promptly and aggressively.
- Make sure sick pets get prompt and appropriate medical attention, since diagnosing plague in a pet may be a critical factor in prompt treatment of people infected by the pet. Plague is an example of a disease for which diagnosing infection in the pet might save the owner's life.
Today's Toronto Star has an article about a reptile club in a Toronto Elementary School. Teacher Jim Karkavitsas runs a session every day that teaches students about a range of reptiles. His menagerie has expanded from one snake five years ago to more than 40 different species in his classroom. Some are loaned out to other classroom's on request and two lizards now make their home in the school's main office.
- Learning about, and interacting with, animals can be very important for kids, especially those who don't get exposure to animals at home and outside of school. It can teach responsibility and empathy, and be the springboard for a range of educational discussions.
- The animals are kept in a room adjoining the classroom, so they are relatively contained and all students aren't forced to be around them (since some kids might be afraid of them). Housing the reptiles in a different room also means students presumably aren't eating in the same room in which the reptiles are housed.
- Kids use hand sanitizer before and after contact with reptiles. This is a very important preventive measure for the problems outlined below, but it's not 100% protective (or usually performed all the time or done properly).
- Mr. Karkavitsas takes the animals home during the summer. A problem with some classroom pets is people don't assume ownership for them to take care of them properly when school's not in session. Similarly, the school's parent council provides $5000 to cover the cost of keeping the reptiles. Hopefully, that also means that veterinary care would be provided if something happens, which can be a problem in many cases when classroom pets need care but no one has a mandate to arrange or pay for it.
The bad and the ugly
- Salmonella. That's the big one. Reptiles are classic sources of Salmonella. You can almost guarantee that more than one of these reptiles are shedding the bacterium. If a reptile is shedding Salmonella in its feces, it will also likely have the bacterium on its skin, in its cage and in any areas where it roams. It also means that anyone touching it (or its environment, or contaminated areas) can pick up Salmonella on their hands, with subsequent transfer into the mouth. This is a high-risk situation since reptiles are a major source of salmonellosis, especially in kids. Reptile-associated salmonellosis does occur in classroooms.
- Mr. Karkavitsas buys frozen rats to feed the snakes. Frozen rats can also be contaminated with Salmonella, and frozen rats have caused salmonellosis in kids in a school (which was also brought home and spread other family members). There's also been a large (and likely ongoing) international salmonellosis outbreak associated with frozen rodents.
- Standard recommendations are that children less than five years of age (along with pregnant women, elderly individuals and people with compromised immune systems) not have contact with reptiles. This is a grade 5-6 classroom, so the students would be older than this, but I wouldn't be surprised if younger kids in the school also have contact with the reptiles. Additionally, the immunocompromised group is an issue, since many people have compromised immune systems due to various diseases or treatments. Teachers may not know about all of these and parents may not realize that their high-risk child is having contact with high-risk animals in school. When you can't be sure that high-risk people won't have direct or indirect contact, that's a problem.
The sentiment is great and I applaud the teacher's efforts to engage kids and teach them about animals, However, it's a cost/benefit situation and the potential costs (which may be extreme) outweigh the benefits (significant as they may be). While reptiles can be great pets in certain situations, they're not meant for schools where there are lots of kids, challenges with supervision, difficulty implementing good infection control practices and potentially individuals at high risk for infection.
It's not the first, and it's a safe bet it's not the last, but a lawsuit has been filed against Diamond Pet Foods in response to a case of salmonellosis in a New Jersey infant. The lawsuit claims (probably correctly) that the infant acquired Salmonella from contaminated dog food that was in the household. The infant was hospitalized for three days but recovered. The lawsuit, one of at least eight that have been filed, claims negligence and fraudulent representation, and is seeking over $75000 in compensation.
In reality, it's hard to consider a company liable simply for Salmonella contamination. Various practices can be used to reduce the risk and to detect contamination when it occurs, but these will never be 100% effective. Standard hygiene practices that are recommended to reduce the risk of exposing people (especially high risk people) to any pathogens that might be found in pet food must therefore always be used. It's hard to say what degree of responsibility needs to be placed on consumers versus companies, since companies need to do their best and people need to use common sense.
From my completely non-legal standpoint, the issues of negligence and liability come in when:
- A company has inadequate facilities that do not conform to standard requirements to reduce the risk of contamination (e.g. duct tape and cardboard in food processing equipment, as per the FDA report).
- A company has an inadequate quality control program.
- A company knows there's a problem and doesn't take prompt and appropriate action to correct it.
Based on what information has been released (including the relatively damning FDA report that cited lack of microbial analysis of certain ingredients, lack of hand hygiene facilities and the use of duct tape, cardboard and other non-cleanable materials in the plant) combined with some questionable communications strategies, it certainly seems like a case can be made here.
From one of my grad students who, contrary to his claim, maybe does spend too much time on YouTube.
While I guess it's getting beyond the point where Hendra virus infections in horses in Queensland, Australia are considered "news," it's still a highly concerning situation. Infections caused by this fruit bat-associated virus continue to occur in the region and there's no sign that this problem is going to go away any time soon.
In the latest report, two horses from a farm where a horse recently died of Hendra tested positive for the virus. In another location, a dog is being re-tested after a weak positive test. This situation brings back memories of the debate that occurred last year after a healthy dog that tested positive was euthanized as a precautionary measure, despite no information about whether the dog could actually be a source of infection.
Hendra is resulting in profound changes in the horse industry in Queensland. Beyond being a major problem in horses, this virus can be passed from horses to people, resulting is tremendous concerns amongst horse owners and veterinarians. Many veterinarians are refusing to work with horses because of the risk and I assume that some people are selling horses for similar reasons.
Infection control practices can presumably reduce the risk of transmission of Hendra virus between horses and from horses to people, but there's no way to completely eliminate the risk. Fruit bat control strategies get discussed, ranging from removal of fruit trees from horse pasture to reduce fruit bat exposure (logical) to fruit bat culls (highly unlikely to have any longterm effect). At a minimum areas under fruit trees should be fenced off from horses, and it has also been recommended to keep water troughs covered to prevent contamination with excrement from the flying foxes. Ultimately, everyone's holding out for an effective vaccine, which has yet to appear, but work on the vaccine is well underway and the hope is that a commercial vaccine could be released as early as next year.
The title from Food Safety News' latest report says it all: "After eight expansions, how big is the Diamond Pet Foods Recall?" It's disturbing that we can't answer that question, considering the contamination stretches back to 2011 and now it's apparent that there are problems with another one of their plants.
Accordingly to Food Safety News, the FDA has indicated Salmonella contamination has been found in Diamond's Meta, Missouri plant, in addition to the South Carolina plant that's been at the heart of the recall. However, the Missouri Salmonella contamination is from Salmonella Liverpool, a different strain from the South Carolina plant where Salmonella Infantis has been involved. So, there's no evidence that the two recalls are linked, although you have to wonder whether deficiencies that were found by the FDA at the South Carolina plant might also be present at other plants, thus creating an increased risk of Salmonella contamination.
Anecdotal information about sick animals and people associated with this recall abounds, in stark contrast to information from Diamond Pet Foods. It would be nice to have some clear communication from the company about this outbreak, and some information about what they are doing to control it and prevent it from happening again. The continued expansion of the recall and contamination is concerning, and in the absence of clear communication from the company it's hard to have confidence in the safety of any more of their products.
A 50-year-old UK woman, the first of two recent travel-associated rabies cases in the UK, has unfortunately but not surprisingly succumbed to the infection.
The woman was bitten by a puppy while traveling in India. Given the widespread nature of rabies in dogs in India and the large number of human rabies deaths associated with canine rabies there, this was a high-risk exposure. I still haven't seen any information about whether she sought medical care in India or not. Too often, people don't bother to go to a doctor after being bitten, especially if the bite appears minor - but even a minor bite can transmit rabies. Furthermore, people don't always get the care they need, since rabies treatment is astoundingly not always offered after dog bites in India, and rabies vaccine and antibody may sometimes be in short supply.
Whatever happened in India, the woman was reportedly turned away twice by doctors back home at Darent Valley Hospital in Dartford, Kent. It's not clear why, and an investigation is underway, but it's not necessarily surprising since signs of rabies can be very vague at first. Initial signs could mimic a range of minor illnesses, and if the doctors didn't know that the woman was bitten by a dog in India, rabies presumably (and reasonably) wouldn't be considered, especially since it's not present in the UK.
In what is hopefully a case of misquoting or misinterpretation, Dr. Ron Behrens of the London School of Hygiene and Tropical Medicine is quoted as saying that there is a 24 hour window after a bite when antibody treatment can prevent the virus from entering the nervous system. In reality, it's not that quick and the incubation period can be very long in some cases. Post-exposure treatment can be highly effective even if it's given well after exposure, as long as it's before signs of rabies occur. Prompt treatment is always best.
Just as I was getting ready to write about a recent case of travel-associated rabies in the UK, a second suspected case has been identified in the UK. They're not linked and it's just a co-incidence that the two have been identified in a short period of time, but they highlight the potential risks of rabies during travel.
The first report is about a confirmed case of rabies in a woman in her 50s who was bitten by a dog in India. At last report, she was being treated in hospital, although the prognosis is presumably extremely poor if treatment was started after the onset of disease. Public health officials have investigated people who were in contact with the woman to determine who needs post-exposure treatment.
There's not much information in the most recent report, beyond the fact that a suspected rabies case was detected in a person in Leeds following a dog bite that occurred abroad. There's no information yet (at least that I've seen) about where the bite occurred, the condition of the patient or whether the person received medical care after the bite.
While travel-associated rabies is very rare, it's almost always fatal. It's almost 100% preventable too, and any cases that occur typically reflect a breakdown in knowledge, communication or medical care.
Knowledge/Communication: People need to know about rabies, and be aware that any bite from a mammal in a rabies-endemic area should be investigated as a potential rabies exposure. They need to know about the risk of rabies in areas they visit, and avoid situations that might lead to a bite. Travelers and non-travelers alike need to know to go to a physician after any bite and to ensure that rabies exposure is duly considered. Individuals traveling abroad need to know how to access the healthcare system where they are, communicate the problem and act as their own advocate to make sure things are taken care of properly.
Medical Care: With proper post-exposure treatment, rabies is almost 100% preventable. The problem is getting the treatment in a timely manner. Knowing to go to a doctor is one issue. Getting proper care once there is another, particularly in some countries where access to rabies vaccine may be limited or where the healthcare system is poor. Rabies exposure is a medical urgency, not an emergency (although the more severe the bite and the closer to the head, the more important it is for a prompt response). If someone has had a potential rabies exposure and they aren't getting proper care, they need to get home (or somewhere else) where they can obtain the appropriate treatment. That doesn't mean panicking and getting on the first flight out of the country, but it also doesn't mean waiting until your planned vacation is over. It means getting home in good time, while not freaking out if it takes a day or two.
The large recall and salmonellosis outbreak associated with a variety of foods produced by Diamond Pet Foods continues to expand, in terms of species involved, the number of cases, the number of recalled products and geographic scope. The only thing that's not expanding in information from the company.
Reports (of varying strength) of Salmonella cases in dogs have been cropping up, but it's not just a US problem or a problem only involving people and dogs anymore. Two cats from a Montreal animal shelter have apparently died. At least two people in Canada have also been infected, one each from Quebec and Nova Scotia.
As with many outbreaks, the depth of information is variable when it comes to potential cases and it's hard to say if everything that's reported in the press is real. Just because an animal has been eating recalled food and gets sick, that doesn't mean that the food caused the disease. Testing is required to make the diagnosis of salmonellosis and confirm the involvement of the outbreak strain. However, enough reports are coming in to be fairly convincing that this is a very large, wide reaching outbreak involving people, dogs and cats, and multiple countries.
Communication is critical when managing an outbreak. It can let companies show they are doing everything that's necessary (and more), demonstrate their commitment to correcting the problem, show how they are helping people with affected animals, and provide confidence that once the problem was identified, it was (or will be) rectified and the product can be considered safe. Some companies shine during outbreaks. Some don't.
Here, communications don't seem to be ideal.
- Another product was added to the recall list, without too much publicity.
- We know recalled food is in the US, Canada and Puerto Rico (with sick people and animals in at least Canada and the US), but has contaminated food gone any further? Importantly, has information about the potential risk gone anywhere the food might have gone, since the FDA's mandate ends at the US border. eFoodAlert reports some concerning information in that regard. The Taste of the Wild website lists over 50 countries where the food is available and a correspondent for the site apparently bought a recalled product in Ireland. What is actually being done to correct problems that lead to the outbreak is also unclear.
- I also haven't seen any press releases from the company addressing the numerous FDA violations that were identified in the outbreak investigation.
Outbreaks happen. Sometimes they're not preventable. Sometimes mistakes happen. That's an unfortunate aspect of life. However, how a company deals with those issues, both in terms of correcting the problem and restoring consumer confidence, is critical, and seems to be lacking here.
A good adage when it comes to outbreak communications is "never announce a problem without announcing a solution." That doesn't mean hide outbreak information (something that is done too often). Rather, it means don't just say that you have a problem. Be clear about your problem and at the same time be clear about what you are doing to fix it. Hopefully, Diamond Pet Foods has an aggressive ongoing response to correct these problems, and that's what consumers need to know about. In the absence of any clear information, we're left wondering whether they are doing anything at all.
I'm getting a lot of questions now about canine aspects of this recall, so I've addressed my take on some of the important issues below.
Can Salmonella cause disease in dogs?
Absolutely. The common myth about dogs being immune to Salmonella (mainly found on raw food sites) is just that: a myth. Dogs can and do get Salmonella infections, and it can make them sick.
Are dogs getting sick because of the recalled food?
I don't know but I suspect they are. There's no reason to think that the strain of Salmonella involved here would infect people but not dogs. The reason that there are reports of human but not canine cases could simply be because there is a formal surveillance and reporting system for humans but not dogs. Also, testing is not commonly performed on dogs with diarrhea, so large numbers of cases could go unidentified.
What would a sick dog look like?
The most common presentation of salmonellosis in dogs is diarrhea. Vomiting, lethargy and lack of appetite may also be present. Diarrhea can range from mild to severe and bloody. Chronic diarrhea can also develop but is less common. Other types of infections such as bloodstream infections can occur, with or without diarrhea, but these are pretty rare.
How do I know if my dog has salmonellosis?
The only was to know is to try to detect the Salmonella bacterium. This usually involves testing of stool samples. Culture is the standard and preferred approach, and is best done by a lab experienced with Salmonella testing and one where selective culture methods will be used. PCR, a type of molecular test, can also be used to detect Salmonella DNA. The quality of these tests (and the labs that offer them) is quite variable, but some of these tests are quite good. The downside is that all you find out with PCR testing is whether Salmonella is present or not. With culture, the bacterium can be tested further to see if it is the outbreak strain, and it can be tested for its susceptibility to antibiotics in the uncommon event that antibiotic treatment is needed.
My dog is healthy but has been fed recalled food. Should he/she be tested?
I don't recommend that. I only want to do a diagnostic test if I have a clear plan regarding how to use the results, which wouldn't be the case is a situation like this. If the dog was positive for Salmonella, I wouldn't do anything special except remind you to avoid contact with its poop (which you should be doing anyway). We don't treat Salmonella carriers - dogs that are healthy and shedding Salmonella will eliminate it on their own, usually within a couple weeks. A negative result also doesn't guarantee that the dog is truly negative. Usually we want multiple negative cultures to rule out Salmonella since it can be shed intermittently and can be hard to detect.
My dog is healthy but has been fed recalled food. Should he/she be treated with antibiotics?
NO. That's the last thing I want to do. Antibiotics are not very effective (or effective at all) at eliminating Salmonella that's living in the intestinal tract. A healthy animal shedding Salmonella is an indication that the body is handling it. It doesn't mean that disease won't occur, but one critical aspect for preventing intestinal infections is the protective effect of the gut microbiota - the trillions of bacteria that are in the gut helping suppress "bad" bugs like Salmonella. My concern with prophylactic treatment is that we might make things worse by suppressing this protective bacterial population and letting Salmonella overgrow in a situation where it otherwise would not have been an issue.
Fox / dog / human, North Carolina
In this case, a rabid fox had a "direct encounter" with several people, then it was killed by a dog. Three people have started post-exposure treatment.
- The article states that the dog was vaccinated against rabies, which is good to hear. However, it goes on to say that exposed pets need to be euthanized or have a 6 month quarantine. In reality, standard guidelines are that unvaccinated pets are treated like this while vaccinated pets undergo a less rigourous 45 day observation at home. Hopefully the discrepancy is simply due to inaccurate reporting and not misinterpretation of guidelines by local officials.
Cat / human, Maryland
A rabid stray cat scratched five people, who have been urged to undergo post-exposure treatment. Officials are calling for anyone who potentially had contact with this cat go to an emergency room.
- However, odds are if someone goes to an emergency room and says they might have had contact with this cat, they're just going to sit around until someone tells them they don't know what needs to be done, or to go home and deal with someone else. Rabies exposure is a medical urgency, not an emergency. People should take a little extra time to work with their physician and/or public health rather than go to the emergency room.
- People who may have had contact with the cat need a proper assessment to determine if they were potentially exposed to rabies, since just being around the cat or having casual contact is not a risk. Scratches are a bit controversial since they are low risk for rabies transmission (unless the scratches become contaminated with saliva from the animal), and there are conflicting guidelines regarding what to do for a person who is scratched.
- This is also a good reminder to stay away from stray cats.
Fox / human, Pennsylvania
In this report, authorities are trying to find a person that cradled an injured fox in a blanket. The fox was subsequently identified as rabid and they need to determine whether the person was potentially exposed to the virus.
- Again, another reminder to stay away from wildlife, and if there is contact with wildlife, make sure rabies exposure is considered.
Bat / human, Indiana
A student was bitten by a rabid bat while he slept in an Indiana University dorm room. He woke up after being bitten (good thing, since he probably wouldn't have noticed otherwise due to the often tiny marks left by a bat bite). He is now receiving post-exposure treatment.
Rabies isn't going away, at least any time soon. People need to be aware of the risks in rabies-endemic areas, take care around wildlife and vaccinate their pets.
Photo credit: Rob Lee (click for source)
After starting off like a simple recall of potentially Salmonella-contaminated dry pet food, the Diamond Pet Food problem has now expanded into a multistate outbreak of salmonellosis in humans linked to exposure to the contaminated pet food. At last count, there were 14 affected people from 9 US states, including 5 who required hospitalization. These numbers could increase since so far they only include people who got sick up to April 1 (because it takes time for Salmonella to be grown in the lab, sent to CDC for testing and the result investigated, later cases may not have been reported yet).
This outbreak involves Salmonella Infantis, a strain that is uncommonly identified in people. Finding an increased number of infections caused by an unusual strain makes it easier to identify an outbreak, as was presumably the case here. This strain has also been isolated from various types of pet food that were produced at the Diamond Pet Foods' South Carolina plant. Despite the name, this strain of Salmonella is not more likely to infect infants, and people ranging from less than 1 year to 82 years of age have been infected.
Details about the types of contact people had with the pet food are limited. 70% of infected people reported having contact with a dog the week before getting sick. How the other 30% could have been exposed is unclear. Sometimes peoples' recall is poor, especially if they had transient contact with a pet. Individuals could have been exposed from environmental contamination when visiting a household where contaminated pet food was fed, without having direct contact with a pet. It's also possible some cases are not directly related to the outbreak and co-incidentally were exposed to the same strain from some other source.
Since we see periodic outbreaks associated with dry pet food, does that mean that other types of pet food are safer? Not really. Canned food is ultimately the safest because of the heat processing, but it's not practical for all animals.
Typically, after a report like this, I get a barrage of emails from people saying "See... we don't have large outbreaks from raw food diets so they are safer." Unfortunately, that's not the case. High pressure pasteurization (HPP) of raw food, a process that uses pressure with minimal heat to kill bacteria, is an effective method for reducing contamination of such products with harmful pathogens like Salmonella, and HPP is now being used by a couple of companies. These raw diets should be quite safe from a Salmonella standpoint. Otherwise, the risk of Salmonella contamination of raw pet foods is still very high, and if anything, the dry food outbreaks show how people can be infected from contaminated pet food.
Why don't we see large outbreaks associated with raw food? Outbreaks get detected because certain patterns or unusual findings are identified. Raw pet food associated outbreaks probably occur but are not as readily identifiable since raw meat contamination is common but involves variable Salmonella types that regularly change. In a situation like that, you can potentially have lots of people getting Salmonella from raw food, but if there is limited commonality in strains and products, it doesn't get picked up as an outbreak. That's particularly true when the strains that are involved are the common ones found in food, since they would often be dismissed on the premise that the person likely got it from some unknown food source. Without large numbers of cases in an area or a cluster of unusual strains, the investigation wouldn't likely get very far and nothing would be reported.
How do reduce the risk of getting Salmonella from pet food (or your pet)?
- Don't feed pets in the kitchen. This practice has been associated with an increased risk of disease in a previous outbreak of salmonellosis in children.
- Wash your hands after handling pet food.
- Don't let young children have contact with pet food.
- Use common sense when handling pet feces.
More information about both Salmonella and issues pertaining to raw diets (including how to reduce the risk) can be found on the Worms & Germs Resources - Pets page.
The CDC is investigating CDC is investigating more cases of salmonellosis associated with feeder rodent contact, caused by the less-than-catchy-named Salmonella I 4,,12:i:-. This strain is the same one that was implicated in a large and prolonged outbreak in the US and UK in 2009-2010 which was also associated with frozen feeder rodents (rodents sold frozen as reptile food) from a single US supplier. The current outbreak has affected people in 22 US states from August 2011-February 2012, and involvement of the same strain from the same source certainly leads to suspicion that this is actually an ongoing problem.
In the latest outbreak:
- 46 people have become sick. As is common, kids have borne the brunt of this outbreak, with the median age of affected persons being 11 years.
- 37% of affected people were kids five years of age or younger. Since this outbreak involved feeder rodents, clearly people aren’t heeding the guidelines that kids of that age shouldn’t be in households with reptiles.
- No two affected people reported buying rodents from the same store. This shows how widespread the problem is and that it must be originating from the place where the rodents are bred and/or distributed, not a focal pet store issue.
Record-keeping at the pet stores complicated figuring out the source. However, two breeders that supplied pet stores received mice from the company that was the source of the 2009-2010 outbreak. This suggests that not only were people exposed from frozen feeder rodents in the earlier outbreak, but that breeding colonies in different areas were infected from that source. This may have allowed wide dissemination of this Salmonella strain into numerous rodent breeding colonies, creating many possible sources of exposure for members of the public purchasing feeder rodents. The large-scale commercial nature of rodent breeding and wide distribution network creates a great opportunity for widespread outbreaks, as is apparent here and with various other outbreaks (including salmonellosis outbreaks from guinea pigs and baby poultry).
If you are going to buy feeder rodents:
- Treat them as if they are carrying Salmonella, because they just might be.
- Keep them away from human food. Keep them in a separate freezer or fridge, or in a sealed container if they have to be in the same fridge as human food.
- Don't handle them in the kitchen.
- Wash your hands thoroughly after handling.
- Keep them away from young children, as well as people with compromised immune systems, elderly individuals and pregnant women. None of these groups should have contact with reptiles either.
Image: A package of frozen rats, as sold commercially for feeding reptiles.
Identification of the strain of rabies in the first person in Toronto to be diagnosed with rabies in the past 81 years has essentially confirmed that the infection was acquired abroad. Toronto Public Health has indicated that the strain obtained from the infected man is one known to circulate in dogs in the Dominican Republic, where the man had been working over the past few months.
Little additional information is being released, including whether the patient is alive (and if so, what his condition is). As part of the typical rabies investigation, 15 healthcare workers and an unknown number of family members and friends have been deemed to have been potentially exposed to rabies from the man and have been offered post-exposure treatment. The risk of human-human transmission is exceedingly low, but given the severity of disease, the logical approach is to err well on the side of caution when considering post-exposure treatment.
While rabies strain typing supports a dog bite as the source, that can't be confirmed at this time since the man was too ill to provide any information by the time rabies was being investigated. Sometimes, exposure is determined indirectly based on information from friends and family (e.g. the person mentioning that he was bitten by a dog) and presumably there is an effort to question people who had contact with the man in the Dominican Republic to try to piece this story together.
A group of flea (or flea and tick) collars have been removed from the market in France following a risk assessment. The review looked at these widely available, over-the-counter products that contain a variety of different chemicals. The determination was that the risks posed by contact with the collars (particularly to children) were unacceptable compared to the benefits.
As with most risk assessments, cost-benefit is the key. With flea collars, you have something containing a chemical that's easily (and commonly) touched by people, and you also have the potential that young children could put them in their mouths. That's the "cost" aspect. The beneficial side is two-pronged. One consideration is the importance of flea and tick control to human and/or animal health. That's certainly significant, since fleas and ticks can be associated with various problems, including infectious diseases and flea allergies. However, the other consideration is whether there are safer and/or more effective alternatives. The answer to that is yes - there are now much better approaches for flea and tick control than flea collars in terms of effectiveness and safety. The disadvantage is that these alternatives are somewhat more expensive and not available over the counter, but the cost and logistics are far from cumbersome.
So, the withdrawal of the flea collars from the market in France is a very reasonable move, and one that needs to be accompanied by information to pet owners that emphasizes that:
- yes, flea and tick control are still important.
- there are much more effective options that are safer for the pet and the family.
- people should work with their veterinarian to determine the approach that best fits their pet(s) and family.
Toronto Public Health has confirmed the diagnosis of rabies in a person in the city of Toronto, the first such diagnosis since 1931. Details are limited at this point, but there appears to be strong suspicion that this is a travel-associated infection.
The affected person is a 41-year-old man who was working in the Dominican Republic as a bartender. He reportedly started to develop signs of illness last month - it's unusual for someone to be clinical ill due to rabies for so long, as typically once signs occur they progress very rapidly (and almost always end in death). Regardless, after he became sick in the Dominican, he returned home to Toronto, presumably for more medical care. He was taken to hospital by police after arrival since he was behaving erratically at customs. It's reported that he had fairly serious signs before leaving the Dominican Republic, including trouble swallowing and fear of food, water and air. Given that, I'm amazed that he was allowed onto a plane, even with the pretty lax approach that airlines typically take towards sick people boarding planes. While I know circumstances can be difficult and options may have been limited, this isn't really a good way to bring someone home from a foreign country with an unknown disease. Fortunately, rabies isn't spread by casual contact, but you have to consider the potential for more easily transmitted diseases when you go ahead and put someone on a plane with lots of other people. Thankfully his erratic behaviour started on the ground, not in the air, and he didn't have a more transmissible disease.
The man's current condition isn't clear. It appears that the diagnosis was made a few days ago and he's being treated in hospital. However, rabies is almost invariably fatal, especially when disease is advanced by the time it's diagnosed.
People who have had contact with the affected man are being evaluated to determine who requires post-exposure treatment. Further testing will be done on the virus to see what strain it is, to provide more information about the possible origin. Most likely, it was from a dog bite, but that's just a guess on my part.
While little information is available regarding this case, it's a chance to remind people again of a few key rabies prevention points:
- Pets should be vaccinated against rabies.
- People (especially kids) should be taught basic bite-prevention practices and to avoid strange animals.
- Any bite from an animal needs to be investigated to determine whether there might have been rabies exposure.
- Rabies is very common in many countries (especially less developed countries), particularly dog rabies. People need to pay extra attention to bite avoidance when traveling.
- Rabies is basically 100% preventable if proper post-exposure treatment is provided. The weak link is often people failing to seek medical care after a bite. That's particularly true for many travelers. If you are bitten while traveling, you need to make sure you get adequate care, or get home to get treated properly, and promptly.
Don't tell Samuel L. Jackson (Snakes on a Plane was bad enough), but on August 2011, a bat was found flying through the cabin of a plane shortly after take-off from Wisconsin. Failing to heed the seat belt sign, it flew around the cabin a few times before it was eventually trapped in a bathroom. The aircraft then returned to the Wisconsin airport...vnot sure whether that was because they were worried about the bat or because they didn't have an available bathroom any more.
Unfortunately, when they got back to the airport, no one thought to close the plane door before opening the bathroom door, so the bat flew out of the bathroom, out of the plane, down the jetway, through the airport and was last seen exiting the airport via automatic doors (smart bat). The problem with the bat's escape is there was then no way to determine whether it was rabid, since even bats with a good sense of direction can be shedding the virus. Because of that, it had to be assumed that the bat was rabid and an investigation ensued.
The Wisconsin Department of Health called the CDC for assistance and a standard investigation was undertaken. A key component was to determine who, if anyone, was potentially exposed to rabies, assuming the bat was carrying the virus. Rabies is spread through direct contact of saliva from an infected animal with broken skin or mucous membranes (e.g. mouth, nose). Most often, this occurs via a bite. Being in the same area as a bat doesn't constitute a risk.
A rabies investigation typically involves interviewing people who were in the same area as the bat to see if they had any contact with it. That was done, but it was complicated by "difficulties obtaining an accurate passenger manifest...". (Considering it seems like I have to do everything short of depositing a DNA sample to fly to the US these days, I can't fathom how they couldn't have a list of who was on the plane.)
Anyway, the airline gave the CDC a list of 15 people that they knew were on the plane and 33 who had reservations (but apparently they didn't know for sure whether they were on the plane). Considering 50 passengers were on the plane (not counting the bat), that left a few unknowns, which was compounded by their finding that some people who had reservations confirmed they were not on the plane. They tried various ways to contact people, but ultimately ended up with 5 mystery passengers.
Fortunately, the risk of rabies exposure in this case is low. All 45 of the contacted passengers reported having no direct contact with the bat, and it's very unlikely anyone else did given the description of what happened. Similarly, none of the pilots (hopefully it was easy to figure out who they were) and other flight or ground crew reported any contact.
An environmental assessment was performed to see if there was a bat problem at the facility, and nothing out of the ordinary was found. They made a few recommendations to reduce the chance of this happening again:
- Use of netting to cover crevices in the airport where bats might roost.
- Extending and retracting jetways before the first flight of the morning (I guess to scare the bat out before a plane is hooked up).
- Training employees on bat capture methods.
- Testing any bats for rabies.
So, it was more of an interesting story than a true disease concern, but with rabies, you have to be thorough to convince yourself that there's no risk.
It also seems like this bat was much more organized than the airline.
As we've discussed previously, rabies has been a big problem in Bali since 2008. Previously rabies-free, this densely populated island has been struggling with a large and persistent canine rabies outbreak that has resulted in numerous deaths and much debate about control measures.
- Dog bites are very common on the island, with a daily average of nearly 100 bites reported over the study period. Since many bites don't get reported, even this large number is an underestimate.
- The average age of affected people was 36 years, with a range of 3-84 years. All 104 died.
- Most of the cases (57%) were male. This is common, although whether it is because men are more likely to be bitten (because of greater exposure or greater provocation) or less likely to seek medical care after a bite is not known.
- There was a history of a dog bite in 96/104 infected people. It's likely a bite occurred for the others as well, but in those cases the patient was unconscious at the time rabies was suspected and family members did not know of any bites.
- The incubation period ranged from 12 day to 2 years. It was less than 1 year in 98% of cases. Very short incubation periods, like the 12 day one reported here, are almost always associated with bites to the head or neck, since it's a shorter distance for the virus to travel up nerves to the brain.
- Early signs of disease are often vague. Pain or numbness at the location of the bite (37%), nausea or vomiting (30%), fever (22%), aches (17%), headache (16%) and insomnia (7%) were most common.
- 81% of people that developed rabies did not undergo any type of treatment. 11% washed the wound themselves. Only 6% went to the hospital on the day of the bite. The people who went to the hospital received a course of rabies vaccines but did not receive rabies immunoglobulin (RIG, which is anti-rabies antibodies). So, while they were treated, they didn't get the full recommended treatment. This is incredibly frustrating since rabies is almost 100% preventable if people get proper medical care. Failure of most of these cases to even seek care is a huge issue, and inadequate treatment of people who sought medical care compounds the problem. Not all of the vaccinated people completed the full vaccine course before developing signs of rabies. These were individuals who had short incubation periods because of bites to the head and neck.
These results are not surprising but demonstrate a few important concepts, including:
- the need for education of the general public to seek medical care after a bite.
- the need for proper education of healthcare providers so that people who are bitten get proper medical care.
- the need for adequate supplies of rabies vaccine and immunoglobulin. It wasn't stated whether people didn't receive RIG because it wasn't offered or (as is common in some regions) it wasn't available.
- rabies may not be considered initially when signs first start appearing, as many of these people ended up being treated for various other potential problems before rabies was considered. While rabies is almost always fatal, there have been very few "successfully" treated individuals (meaning they didn't die, but they can still have long-term neurological impairment), but to have any chance at success, treatment needs to be administered as quickly as possible.
- control of canine rabies is a key part of controlling human rabies.
Max, a 12-year-old Chihuahua from Greenfield, New Jersey, was euthanized recently after he was exposed to rabies. While far from unusual, the case highlights the ongoing risk of rabies exposure as well as issues with understanding of rabies guidelines and communication.
Max was attacked by a rabid raccoon - an ever-present risk for animals that go outside (or get outside) in many regions. Animal control was called and the raccoon was caught. It was euthanized and rabies was confirmed, indicating that Max was very likely exposed to the virus.
Here's where things seem to get strange. The paper reports:
"Once exposed to a rabid animal, a six-month quarantine is required for the exposed animal, even those animals that have been inoculated with a rabies vaccine."
- Not really. In Canada, standard guidelines are for a 6 month strict quarantine for dogs (and cats) that are not properly vaccinated, but only a 45 day observation period is required for vaccinated animals. I don't know if in this jurisdiction they made up their own different rules, whether someone doesn't know what's supposed to be done or whether it's poor reporting, but it's a concern because it can be a difference between life and death... not necessarily from rabies, but from the quarantine requirements alone. People are often unwilling to undertake a strict 6 month quarantine and choose euthanasia (as was the case here), while the 45 day observation period is much more acceptable.
The attending veterinarian stated "Because of the way it was exposed and because of the positive, I think there was a really good chance this dog was going to get rabies".
- It's certainly possible, and nowhere does it say whether Max was properly vaccinated. However, there's a reason we vaccinate. It's a highly effective vaccine and we're trying to prevent disease. Nothing's 100%, but with proper vaccination, the risk of rabies is greatly reduced.
It's also stated that "due to the nature of rabies, until behavioral changes occur, the animal is not infectious".
- While this doesn't have anything to do with Max's situation, it's not true. Animals can shed the virus for a short period before they show signs of illness. That's the reason there is supposed to be a 10 day quarantine period after a dog bites someone - to see if the dog develops signs of rabies (which would have major implications for the person who was bitten).
Curiously, the article ends with a reminder to vaccinate pets, which seems kind of strange if their assumptions are that an exposed animal will get sick irrespective of vaccination status and that vaccination will have no impact on what happens to an animal after exposure.
However, despite the miscommunication, the take-home message emphasizing the need for vaccination should be heeded. As well, people making decisions about what to do after rabies exposure should make sure they do so based on the best evidence that's available, namely the Compendium of Animal Rabies Prevention and Control.
.A five-month-old Britich baby was hospitalized with salmonellosis that was presumably acquired from a family pet. The baby developed severe diarrhea and was rushed to hospital. Fortunately, the child has recovered, something that's far from assured in such cases, since salmonellosis can be life-threatening in infants.
As expected, an investigation followed the diagnosis of salmonellosis. Typically, these investigations focus on food and animal contact, and since this family had a bearded dragon (see picture) and tortoises, the investigation honed in on the reptiles. Reptiles are high risk for Salmonella shedding and are commonly implicated in human infections. Further, the type of Salmonella that infected the infant, S. Pomona, is commonly associated with reptiles. It doesn't sound like they've confirmed that the same strain of Salmonella was present in the reptiles, but I assume that testing is underway.
Reptiles should not be present in households with infants. It doesn't matter if the animal never leaves its enclosure, because while the critter may not leave the enclosure, Salmonella will.
In low risk households (households without kids less than five years of age, elderly persons, pregnant women or immunocompromised individuals), good management practices can be used to minimize the risk of transmission of Salmonella, but given the potentially fatal nature of salmonellosis in infants and other high-risk individuals, these precautions are not adequate in high-risk households. While reptiles can be great pets, they're just not worth the risk in some situations.
The CDC has announced an investigation of three multistate outbreaks of salmonellosis linked to pet turtles. At last report, 66 affected people had been identified, and since most outbreaks like this only identify a minority of cases, it's safe to assume there are many others.
- Three different types of Salmonella have been implicated; S. Sandiego, S. Pomona and S. Poona.
- Infected people have been identified in 16 US states (see map).
- 11 people have been hospitalized, but no one has died.
- Most cases (55%) have involved children under the age of 10.
- Almost all infected individuals who provided information about turtle contact with said the turtles were less than 4 inches long.
This ongoing outbreak, dating back to September 2011, has all the hallmarks of a pet turtle-associated outbreak: a large number of cases over a wide area and prolonged period of time, a predilection for young children, and the potential for severe disease. While far from novel, this outbreak also highlights some recurring themes.
The potential for widespread outbreaks from mass production and distribution of pets has been repeatedly demonstrated with a range of diseases, including recent examples involving chicks and guinea pigs. That doesn't mean that mass production is necessarily higher risk (although it certainly can be), but when something goes wrong, it can go very wrong because of the large number of infectious animals that get sent out.
Sale of turtles with shell lengths under 4 inches has been banned in the US since 1975. This is because small turtles are more likely to be handled (and potentially put in the mouth) by young kids. Despite extensive lobbying by US turtle breeders, the law remains in effect, but it's widely flaunted. It's surprising more efforts aren't put into enforcing this regulation given the number of people who are sickened every year from contraband turtles. (It's also surprising that infected people in the US haven't started large lawsuits against people distributing small turtles.)
Anyway, this is yet another reminder about the risks associated with reptiles and high risk individuals (i.e. young children, elderly, pregnant, immunocompromised) and the need for pet turtle owners to follow basic hygiene and infection control practices. More information about turtles - for owners, veterinarians and healthcare professionals - can be found on the Worms & Germs Resources page.
Local media are reporting an apparent case of West Nile virus infection in a horse in Northampton County, Pennsylvania. This is surprising since, while I know there are certainly mosquitoes emerging early with this mild weather, seeing active mosquito-borne infections at this time of year would be very unusual. That's particularly the case with West Nile virus, since it tends to be a late summer and fall disease based on the mosquito types that are predominant at that time of the year.
Information about this West Nile virus case is pretty sparse. The report simply says the horse was euthanized because it was "suffering from the virus." Knowing if and how it was actually diagnosed is important to determine whether it was truly an active infection or a false-alarm, like this winter's report of West Nile virus in British Columbia.
Regardless, it's still a good reminder that we are now heading into the time of year when we have to think about mosquito-borne diseases in various species (including people). Measures to reduce mosquito populations, such as eliminating standing water (see picture), and mosquito bite avoidance are always good, regardless of what diseases are currently being diagnosed.
Image source: www.saskatoonhealthregion.ca
Authorities in Hawaii are advising people in Oahu to eliminate standing water as a mosquito control measure. While it's always a good idea, it's of particular concern in this case bacause a rare type of mosquito, Aedes aegypti, was found around the Honolulu International Airport. This mosquito species is a highly effective vector for various infectious diseases, including dengue fever and yellow fever.
What does this have to do with companion animal disease? Well, nothing directly, but it's a good reminder of how infectious diseases can easily reach a distant area (even Hawaii) in a short period of time.
There are a plethora of mosquito-borne diseases out there, and presumably we don't even know about many of them. Mosquitoes don't fly very far, which helps contain these diseases to certain areas. However, mosquito-borne diseases can still spread over wide ranges if either the pathogen or the mosquitoes are hitch-hiking.
A common way for pathogens to travel is in various kinds of animals (especially birds) that can harbour the pathogen (usually a virus) and infect mosquitoes in distant areas.
Modern transportation can be an effective vehicle for pathogen-laden mosquitoes. Theoretically, all it takes is for a single infected mosquito to hop onto a plane and survive the flight to a new region. If the mosquito bites a susceptible host, it can cause a rare disease - that's of particular concern since it's unlikely that an exotic foreign disease in someone who has not left the country would be promptly diagnosed (and therefore promptly treated). Even worse, the disease could establish itself in the new region if a series of things happen:
- The mosquito has to bite something or someone.
- That something or someone has to be susceptible to the pathogen and that pathogen needs to grow inside the host's body to high enough levels that it can infect another mosquito.
- Another mosquito that can carry the pathogen must come along, bite the infected individual and acquire the pathogen.
- The new mosquito must then find another susceptible host to bite.
- The above needs to be repeated enough times that the pathogen establishes a foot hold in the area and starts causing disease.
Is this common? No.
Is it possible? Yes.
West Nile virus is an example of what can happen. This mosquito-borne virus came out of nowhere in North America in the early 2000's and caused widespread illness and death in humans, horses and various other species. Did it arrive via a mosquito on a plane? No one knows, but it's certainly a possibility.
At this time of year, I start to see ads from local feed supply stores about annual chick sales. Overall, it's not a big deal and most people that buy chicks don't have problems. However, it can be a particular concern for certain high risk groups, particularly young children, and outbreaks of salmonellosis are a recurring issue.
Contact with young poultry is considered very high risk for Salmonella exposure, since Salmonella shedding rates amongst the little guys are pretty high. Most outbreaks of salmonellosis disproportionately involve young kids, due to a combination of increased handling, poor hygiene and inherent increased susceptibility of young kids to infection. The problem is that sometimes people buy chicks because their young kids want to raise and handle them. Outbreaks associated with sales of young chicks, as well as hatching chicks in schools and daycare, have been reported.
A recent CDC report describes yet another multistate outbreak of Salmonella, this time associated with a mail-order hatchery.
The outbreak occurred from February to October 2011 and was first noticed through lab-based identification of clusters of Salmonella Altona and Salmonella Johannesburg. Ultimately, 68 cases of S. Altona and 28 of S. Johannesburg infection were identified in 24 states. Here are some highlights:
- 32% of people with S. Altona and 75% with S. Johannesburg were kids 5 years of age or younger.
- 74% of people with S. Altona and 71% of people with S. Johnannesburg reported recent contact with young poultry.
- Most people that had poultry contact reported purchasing chicks or ducklings at local agricultural feed stores. These stores got the chicks and ducklings from a single mail-order hatchery.
Mass production of animals for widespread distribution, whether it's guinea pigs like I wrote about the other day, or chicks and ducklings here, increases the risk of widespread outbreaks because a single focus of infection can have far-reaching effects.
Mass production and mail-ordering of chicks isn't likely to stop, so what can people do to reduce the risk?
- Keep high-risk people (that is kids 5 years of age or less, elderly individuals, pregnant women and people with compromised immune systems) away from young poultry. This includes keeping chicks out of schools, where hatching chicks is still performed in some areas.
- Use good hygiene practices when handling chicks or anything in their environment. Assume that all of the chicks are shedding Salmonella and treat them accordingly. By that I mean use good general hygiene practices, particularly hand hygiene, to reduce the risk of exposure.
- Stores selling chicks should also provide basic safety information to inform and remind people to use appropriate practices to reduce the risk of infection.
Botulism outbreaks in horses are usually bad news. Horses are very susceptible to botulism, and outbreaks in horses caused by contamination of food often end up killing multiple horses on a farm. The recent botulism outbreak in Reddington, IN is another reminder of how deadly it can be.
The outbreak involved a family that lost five horses to suspected botulism. "Suspected" because this disease can be hard to confirm sometimes, although it's usually possible to make a pretty solid presumptive diagnosis based on how the horses look and by ruling out the few other possible causes. The details are pretty sketchy. Apparently there are some other sick horses, but how sick they are and how many isn't clear.
Botulism occurs in two ways. In adult horses, it almost invariable occurs after ingestion of the extremely potent botulinum toxin produced by the Clostridium botulinum bacterium. In foals, it usually occurs after ingestion of the bacterium, which then produces toxin in the foal's intestinal tract.
In adults, outbreaks are usually associated with contaminated feed. There are some high-risk feeds like haylage and silage (see photo) that we usually focus on first, but sometimes botulism toxin can be found in hay or other common feeds. Haylage, silage and other fermented feeds become a problem with they are improperly fermented, allowing the Clostridium botulinum to grow and produce its toxins. Sometimes, contamination of feeds can occur when an animal that has died of botulism (and has the bacterium and its toxins in its body) gets incorporated into hay or other feedstuffs.
When an outbreak is suspected, a key step is removing any potentially contaminated feeds to reduce further exposure, although often it's too late by the time the disease is recognized. Antitoxin (which is pre-formed antibodies that help neutralize the botulinum toxin) can be given to exposed horses, but it's extremely expensive and does not reverse any damage that's already been done. That's why these outbreaks are often so disasterous, because when the diagnosis is made the only thing left to do may be damage control to try to save some of the less affected horses. That's tough because botulism has a very high mortality rate in horses.
The farm owners in Reddington are urging local horse owners to be on the lookout for botulism. It's reasonable, but rarely do we see multi-farm outbreaks from botulism. They also state that botulism doesn't affect cattle, which is wrong. Cattle are more resistant than horses, but they certainly can get botulism.
A botulism outbreak in horses poses little risk to people. People are susceptible to this horrible disease as well, but to get it someone would have to ingest the same contaminated feed that the horse did. There's no risk of transmission of botulism from an infected horse to a person or another animal.
Guinea pigs are relatively benign pets in terms of zoonotic diseases, but like any animal, they can carry some pathogens that are transmissible to people. This was highlighted in a poster presentation at the recent International Conference on Emerging Infectious Diseases in Atlanta. The poster (Bartholomew et al) described a CDC investigation into an outbreak of Salmonella Enteritidis infections in people in multiple states in 2010.
Here are some highlights:
- The first affected person was a child who purchased a guinea pig from a pet store. The animal looked "frail" and was housed with the child's existing guinea pig. Later that month, both guinea pigs developed diarrhea and died. Shortly thereafter, the child developed diarrhea, fever, cough, chest and back pain, a rash and some other signs. Ultimately, a Salmonella infection of the sternum was diagnosed, indicating that Salmonella had traveled from the intestinal tract to the child's bloodstream and set up an infection in the breast bone.
- The CDC investigation focused on other people who had been diagnosed with the same strain of S. Enteritidis. They identified 10 such cases who also reported guinea pig exposure, scattered over 8 US states.
- The same Salmonella strain was also identified in guinea pigs, including one from a Texas guinea pig broker, around the same time as these cases were occurring.
- Most of the affected individuals were children. Three had purchased guinea pigs from the same pet store chain as the first child. Three other affected people were employees of stores from that pet store chain.
- Testing of the environment in pet stores from that chain did not identify Salmonella. However, since sampling was done well after people got infected, it doesn't mean it wasn't there earlier.
- No common guinea pig source supplier was found, but one Pennsylvania breeder was identified as a possible source for the cases associated with that pet store chain.
This is pretty strong evidence that the infections were guinea pig-associated.
Some take-home messages:
- Any animal can be a source of potential infection, and general hygiene practices should be used all the time to reduce exposure to pet feces.
- Sick animals might mean the potential for sick people. While it's sometimes tough to convince people that testing dead animals (especially dead animals that don't cost much) is useful, it might have had a great impact on the care of the first child. If physicians knew that the child was exposed to Salmonella, they might have been able to make the diagnosis much quicker.
- Pet stores are not uncommonly implicated as sources of outbreaks, and there are also risks to their staff. Pet stores need to have good infection control, hygiene and disease reporting practices.
- The nature of pet rodent distribution, with large breeders sending animals to brokers where large numbers of animals get mixed and sent on to pet stores, creates the potential for widespread disease transmission, as has been repeatedly shown in the past.
The Ontario Ministry of Natural Resources and Welland SPCA are warning people about an apparently large number of cases of distemper in raccoons in the area. Distemper is a pretty nasty disease which can be spread between dogs and wildlife. It’s caused by canine distemper virus, but the "canine" part of the name can be a little misleading, since this virus readily infects some other species such as raccoons.
In addition to the problems with sick and dying raccoons caused by the outbreak, there are two main concerns for pet dogs:
One concern is the potential for wildlife to transmit canine distemper virus back to dogs. It’s hard to say what the risk of that is, and the risk would be primarily to young dogs that are not adequately vaccinated. If a dog has an encounter with a raccoon that is sick with distemper, it’s possible the pet could be exposed to the virus. Dogs are also probably more likely to have close encounters with sick raccoons that are unable or unwilling to run away, as opposed to healthy raccoons. If an inadequately vaccinated dog gets exposed, it can get very sick, which is obviously bad for the dog, and also creates another potentially infectious animal to keep passing the virus along.
The other concern is differentiating distemper from rabies. Distemper can cause signs that are very similar to rabies. If a dog has an encounter with a raccoon that is behaving abnormally, rabies is a big concern. If a dog is exposed and the raccoon is not available for rabies testing, the dog would require a 6-month strict quarantine or euthanasia if it's not vaccinated (or not adequately vaccinated), or a 45 day "observation period" (on a proverbial tight leash) if vaccinated. These measures aren’t easy to implement, and unvaccinated dogs often end up being euthanized because owners don’t want to go through the hassle of a 6 month quarantine.
What does this mean to the average pet owner? Well, nothing that they shouldn’t be thinking about anyway. This just increases the relevance of some routine measures such as:
- Keeping dogs that are outside are under control so they don’t encounter wildlife.
- Ensuring dogs are properly vaccinated against distemper and rabies.
- Taking particular care to prevent exposure of young unvaccinated dogs to wildlife.
- Discouraging raccoons from taking up residence in yards.
Nothing earth-shattering, but these basic precautions can greatly reduce the risk of disease transmission from wildlife to dogs, be it rabies, distemper or other bad bugs.
An interesting and frankly somewhat scary report in an upcoming issue of Veterinary Microbiology (Clegg et al 2012) provides further information suggesting that cats might be a source of canine parvovirus infection. This potentially fatal infection, which typically affects young unvaccinated (or inadequately vaccinated) puppies, is a major problem, and outbreaks occur (not uncommonly) in some high-risk populations like shelters.
In the 1970s, a new form of canine parvovirus, CPV-2, emerged and rapidly spread worldwide. That predates my veterinary career but I've heard stories of clinics where you couldn't turn a corner without stepping on a dog that was hospitalized for treatment of parvo, since it was a new disease and vaccines were not yet available. CPV-2 was shown to be able to grow in cat cells in the lab, but not in live cats, so it was generally assumed that dogs had CPV and cats had their own closely related virus, feline panleukopenia virus (FPLV). However, new variants of CPV-2 have emerged over time, and these seem to have a greater ability to infect cat cells in the lab, and disease caused by these strains has been reported in cats both experimentally and in limited real-world situations. However, it was still considered an uncommon event and the role of cats in parvovirus infection of dogs was largely thought to be inconsequential.
Or maybe not.
In this new study, researchers collected fecal samples from 50 cats in a cat-only shelter, and 180 samples from 74 cats at a shelter than housed both dogs and cats. Canine parvovirus shedding was identified in 33% of cats from the cat shelter and 34% of samples from the dog/cat shelter. A concern with a study like this is cross-reaction of tests for CPV and FPLV, but they went a few steps further to confirm that the virus was indeed CPV, not its feline relative. They also showed they could grow the CPV from fecal samples in cells in the lab, which means they were detecting live virus in the animals, not just dead viral bits working their way through the cats' intestinal tracts.
The results are interesting and concerning, since they showed that a pretty large percentage of cats in some situations could be shedding live CPV, making them a potential source of infection for dogs (and possibly other cats).
What makes this even more concerning is the duration of shedding that they identified when they collected samples from the dog/cat shelter over time: cats shed the virus for up to 6 weeks, despite appearing healthy.
This raises concerns about the potential role of cats in the spread of CPV. Cats and dogs don't tend to mix much in parks or outside, but CPV is a very tough virus that can survive for a long period of time in the environment. It's certainly plausible that cats could be depositing CPV-laden feces in the outdoor environment, and since the virus can survive the outdoor exposure and some dogs are notorious poop-eaters, it's a route of transmission that can't be dismissed. Cross-contamination within shelters is also a concern.
The true role of cats in canine parvovirus infection isn't known and it's probably quite limited compared to dog-to-dog spread. However, this study shows that we at least need to be thinking about it and considering cats when dealing with parvovirus problems in shelters and households.
Some things to think about:
- Young puppies should be kept away from cats, especially strays and cats from shelters, until they are properly vaccinated.
- Parvo is one more reason to have good physical and procedural separation between cats and dogs in shelters.
- If a parvo outbreak in underway in a facility, prevention of potential cross-contamination from cats is required.
- If a cat has been in contact with a dog with parvo, it should probably be considered potentially infectious and kept away from susceptible dogs for at least a few weeks.
- Canine parvovirus vaccination is highly effective in dogs. If a dog is properly vaccinated, the risk from cats (or other dogs for that matter) is minimal.
While rare, Morocco continues to be a source of rabies in European animals. The latest case involved a puppy imported into the Netherlands. The (somewhat) brief version of what happened goes like this:
- On Jan 28, 2012, a Dutch couple bought an 8-week-old puppy in a parking lot in Morocco. The puppy was taken to a local veterinarian, microchipped and given a certificate of good health. It would have been too young to vaccinate against rabies.
- On Feb 4, the couple travelled from Morocco to Spain by car and ferry. They then obtained a European pet passport from a Spanish vet, despite the fact that the dog was not vaccinated against rabies (an EU requirement for a pet passport).
- On Feb 11, they returned to the Netherlands. Customs officials "cuddled" with the puppy but apparently didn't ask about rabies vaccination. When they got home, the couple exposed the puppy to many family and friends.
- On Feb 14, the puppy started to become aggressive. They contacted a veterinary practice, and it was assumed the problem was stress, so a sedative was given. (It's not clear whether the puppy was actually examined. If not, that's a pretty big mistake.)
- On Feb 15, the puppy was uncontrollable. The report states "When they realized that the puppy originated from Morocco, the veterinarians contacted the Netherlands Food and Consumer Product Safety Authority (NVWA)." The puppy's history should have been a basic question asked when the couple first contacted the veterinary practice about the animal. Regardless, the concern about rabies came to the forefront with that information, and the puppy was euthanized. Rabies was confirmed that evening (a pretty impressive turnaround time for rabies testing).
- As is typical, an investigation was launched, and a search for people who had contact with the puppy during the period when it was potentially infectious was started. That's not easy when it involves multiple countries, as was the case here, since the potentially infectious period is 10-14 days prior to the onset of clinical abnormalities. The potential contacts included the Moroccan veterinarian, some friends in Spain, the Spanish veterinarian, three customs officials, a couple of unknown people in a Spanish restaurant and at the Malaga airport, and 43 people after arrival in the Netherlands (plus an unknown number of people who petted the puppy on the street).
- Contact doesn't mean exposure, since rabies isn't transmitted by casual contact, so the type of contact was queried further. The risk is from bites or contact between the dog's saliva and broken skin or mucous membranes (e.g. mouth, eyes). Because of concerns that kids don't accurately recall the type of contact they have (meaning they might fail to mention a little nip or some other high risk contact), all nine children who had contact with the puppy were given post-exposure prophylaxis. The Dutch friends in Spain reported high risk exposure and were also treated, however they had to return to Amsterdam for full treatment since anti-rabies immunoglobulin (antibody) was not available in Spain. Information was provided to Moroccan officials but information about what happened there wasn't available.
- Overall, it is stated that 45 people needed post-exposure treatment (although who those 45 were isn't really clear). That's a pretty large exposure, resulting is much angst and expense.
- Two cats and a dog were also exposed to the puppy. The dog had been vaccinated, and received a booster. (It would also be standard protocol to quarantine them for 45 days as well, but that's not stated.) The cats were euthanized because a "suitable quarantine place was not available," a rather strange statement since quarantine isn't a very high tech procedure.
Obviously, this is of relevance to people that live in Morocco or are going to get a dog from Morocco. Those people need to be aware of rabies, be careful when getting a pet, ensure their pets are properly vaccinated against rabies and be careful around stray animals. This report also highlights a couple of other issues:
- A parking lot isn't a good place to buy a puppy, for many reasons. A reputable breeder isn't going to sell a puppy there, and there are lots of good, well-evaluated puppies available through good breeders and shelters.
- Pet importation requirements are pretty weak in a lot of ways, especially if no one actually pays attention to them. That seems to be a recurring theme as well with these imported rabies cases. Here, the puppy was given a European dog passport without the required rabies vaccination, and was not kept in quarantine after arrival. It also went through no less than three customs points in transit, where no one queried rabies vaccination status. The mandatory 3 month quarantine would have prevented exposure of most of the people that required post-exposure treatment.
- Visitors to areas where rabies is endemic in the dog population need to be aware of it. Encountering stray dogs isn't exactly rare in many countries, and while staying away from strays is a good general rule everywhere, people should be particularly careful in areas where the risk of rabies is high. Travelers also need to be aware of what to do if they are bitten by a stray animal.
The parents of a US soldier who died of rabies after being bitten by a dog while deployed in Afghanistan want their son's superiors to be held accountable. Specialist Kevin Shumaker died last August, eight months after being bitten by a dog. An Army investigation concluded that he died because members of his unit ignored rules prohibiting keeping pets (they were befriending feral dogs) and that he didn't seek treatment or notify the chain of command after being bitten. His parents feel that their son is being falsely blamed and that people who should have known better didn't do their jobs. It's a complex issue with some interesting questions.
What should the average soldier know about rabies?
It should be assumed they know absolutely nothing to start off, and a risk assessment should be performed for each deployment to determine what they need to know. When they are being deployed to a rabies-endemic area, they need to learn to stay away from dogs and report dog bites promptly, and why.
Whose job is it to report a bite?
At the end of the day, everyone has to be their own advocate and make sure they report any possible rabies exposure. People up the chain of command don't see everything and individuals need to protect themselves. However, once the bite is reported, others have to act. That might be the breakdown here.
Was anyone actually notified?
The Army's investigation actually documents the fact that Spc. Shumaker notified other personnel at least twice. One was a veterinary corps officer and the other was the person doing his post-deployment health screening. Here's where the ball was probably dropped. Every veterinarian knows about rabies. A veterinarian working in a rabies endemic region is certainly aware of the risks and has a responsibility to act on a reported bite. I find it astounding that a veterinarian in this situation wouldn't initiate a response, particularly given the fact that (at least in my limited experience) the US Army Veterinary Corps has some excellent veterinarians, so this seems rather strange. Further, what's the purpose of a post-deployment health screening if health issues that arise are ignored? If the person doing the health screening didn't understand the concerns about rabies, he or she was inadequately trained and shouldn't have been doing the job. If the screener was properly trained and didn't report it, he or she was incompetent, plain and simple.
Would anything have changed the outcome here?
Absolutely. Rabies is almost 100% fatal, but it's almost 100% preventable when post-exposure treatment is given before the onset of disease. There was lots of time in this case between the bite and when the soldier became ill, and if he had been treated following one of these reports, you can almost guarantee he would not have developed rabies.
Whose fault is this?
Well, everyone plays a role here. The soldier ignored the animal contact rules. Superior officers on base presumably ignored the fact that they were ignoring the rules, probably not thinking about the possibility of rabies, and seeing the positive effect on morale of interacting with the dogs. If the veterinary officer and post-deployment health screener were told about the bite and did nothing, they played a huge role since they, of all the people in this chain, should have known better.
What should happen here?
Rather than fighting over who's to blame (the usual response), an investigation should figure out why this happened and how to prevent it from happening again, largely via better training and clear expectations of personnel.
Hopefully that's happening, since Deputy Commanding General Maj. Gen. William Rapp recently approved a series of recommendations, including:
• Further investigation to see if any members of the unit should be disciplined for their actions or omissions during the unit’s deployment to Afghanistan
• Institute an animal-borne disease surveillance program, standardize rabies vaccine requirements and improve dog bite reporting requirements (I'm surprised that wasn't already the case)
• Reinforce animal bite and rabies training for veterinarians and post-deployment health screening staff
Rabies is pretty rare in horses in North America, with only 37 reported cases in the US in 2010 and 1 in Canada in 2011 (the latest years for which data are available). So, finding two apparently unrelated cases of rabies in horses in the same area in the same month is pretty unusual and concerning. Yet, that's what's happened in Tennessee, where rabid horses were identified in both Rutherford and Marshall counties in January.
Little information is available about the cases, but both were identified as having the skunk rabies virus variant. That doesn't necessarily mean they were infected by skunks (since other species can be infected by this virus variant) but it is suggestive, and indicates that rabies must be active in the skunk population in that region.
Regardless of the source, these cases are a reminder of why rabies vaccination of horses is important, and why rabies vaccination is considered a "core" equine vaccine by the American Association of Equine Practitioners. Rabies is invariably fatal in horses and it's also a major public health risk. While I've been unable to find confirmed cases of horse-to-human rabies transmission, it's a possibility, and additionally, rabid horses have killed people because of their unpredictable and aggressive behaviour.
Vaccination is cheap insurance against rabies - it's never a 100% guarantee, but it's a whole lot better than without vaccination.
There's been a lot of publicity (aka hype bordering on paranoia, including a recent article in the Toronto Star) about the cat-associated parasite Toxoplasma gondii lately. Cats are the definitive host of this parasite and it can cause serious disease in certain people: in pregnant women who have not been previously exposed to the parasite it can infect the unborn fetus, and it can cause severe illness (including neurological disease) in people with severely compromised immune systems. It's also been very loosely implicated in various other conditions, but much of the information gets overblown, as there is lack of solid evidence of a role of Toxoplasma in most of these cases. Unfortunately, cats end up getting a bum rap in the process, even though most Toxoplasma infections don't come directly from cats.
Nonetheless, toxoplasmosis is a potentially devastating disease in some circumstances. and taking measures to reduce exposure to the parasite makes sense. To do this you need to know what makes cats more likely to be infected, so that these factors can be modified. A recent paper in Preventive Veterinary Medicine (Opsteegh et al. 2012) investigated risk factors for cats having antibodies against Toxoplasma. It's important to note that the presence of antibodies means the cat was exposed at some point and mounted an immune response, not that it's currently shedding the parasite in its feces. Most cats only shed Toxoplasma in their feces for a very short window of time (a week or two) after initial exposure, and that usually occurs early in life. Therefore, it's rare for older cats in households to be shedding the parasite.
The research group found 18% of cats they tested had antibodies against Toxoplasma, and they identified a few factors associated with previous Toxoplasma infection:
- Age: Younger cats were less likely to have antibodies. The likelihood of having Toxoplasma antibodies increased steadily from 1-4 years of age.
- Presence of a dog in the house
- Being a former stray
- Feeding raw meat
Most of these make perfect sense and are consistent with other studies. Cats typically get infected by ingesting Toxoplasma cysts found in the muscle of other animals. So, cats that are outside (indoor/outdoor cats, former strays) and hunt, or cats that are fed raw meat are more likely to be exposed. Analysis of the data indicated that hunting contributed the most.
So, while the risk of Toxoplasma infection for the average person is pretty low, some basic management practices can further reduce any risk:
- Keep cats indoors: This greatly reduces the chance they will be exposed to the parasite. It is also good idea for several other reasons.
- Don't feed cats raw meat: Cooking meat to the recommended temperature and time will kill any encysted parasites - this also helps prevent exposure of people eating the meat (to Toxoplasma and lots of other bacteria).
- Control rodents in the house (not by getting a cat!): Indoor cats can still be exposed to various infectious agents through catching mice. I know it's not always easy or even possible (my cat still catches the odd indoor critter) but taking measures to reduce the likelihood of this is wise.
Other important preventive measures include:
- Changing the litterbox regularly, especially if a high-risk person has to do it. Toxoplasma oocysts need at least 24-48h in the environment to become infective. If feces are removed daily, they don't get that chance.
- Clean up any fecal accidents and remove any fecal staining of the haircoat (e.g. poop stuck around the rear end of long-haired cats) promptly, before that 24-48h window expires.
- Wash you hands regularly, especially after contact with the litterbox or any potentially contaminated areas.
- Wash vegetables and cook meat properly. You're more likely to get Toxoplasma from food than from your cat.
More information about Toxoplasma can be found on the Worms & Germs Resources page.
I've written about this topic before, but it's an important (and increasingly common) issue to understand, so bear with me while I address the subject again.
I typically get multiple case consults in person, by phone or by email about methicillin-resistant (MR) staphylococci every day. A lot of these start with "I have a case with an MRSA infection..." While trying not to be rude, I tend to interrupt the conversation at that point with "Is this actually Staph aureus or another staph?"
I do this for a few reasons:
- A few years ago, the vast majority of "MRSA" infections in dogs, cats, horses and other companion animals were actually MRSA - that is methicillin-resistant Staphylococcus aureus. However, in the past few years, there's been a tremendous upsurge in other MR-staph, particularly booming numbers of MR-Staphylococcus pseudintermedius (MRSP) infections in dogs. These days, if it's a dog or cat, when I ask the "What staph is it?" question it's usually not actually MRSA. We're starting to see more MRSP in horses too, complicating things in that species as well.
- Staph are divided into two groups, coagulase positive species (which include S. aureus and S. pseudintermedius) and coagulase negative species. The coagulase negative species are commonly found in or on healthy animals and are often methicillin-resistant, but they are not very virulent and don't usually cause disease outside of very high risk populations (e.g. very sick animals in a veterinary hospital). If a MR coag-negative staph is isolated, I am far from convinced it's the culprit, and typically the real cause of the problem still needs to be found.
- MRSA is much more of a concern from a public health standpoint, as it can move between animals and people. While MRSP can cause human infections, these are extremely rare.
- MRSA is not really adapted to live in dogs, cats, horses and many other animals. It can, for a while, but doesn't do so longterm, and the vast majority of MRSA carriers will get rid of it on their own. In contrast, it appears that MRSP (at least in dogs) can stay with the animal for a very long period of time. Therefore, an animal that has had an MRSP infection has a reasonable chance of shedding the bacterium for a long period of time, which might be of relevance for its health in the future.
- The two main MR-staph of concern in companion animals are MRSA and MRSP. Some diagnostic labs still don't try to differentiate the two, despite the fact that there are different guidelines for determining whether they are methicillin-resistant. If someone has a result that doesn't differentiate MRSA from other staph, I tell them their lab isn't doing things right and they need to talk to them so they can have confidence in the results.
More information about MRSA and MRSP can be found on the Worms & Germs Resources page.
Yet another outbreak of salmonellosis traced back to pet turtles has been investigated by CDC and Pennsylvania's State Health Department. Pet turtles are notorious Salmonella vectors, for several reasons, including the fact that small aquatic turtles very commonly carry the bacterium, they are marketed towards young kids (who are increased risk of infection), and people tend to use poor (or no) hygiene practices when handling turtles or having contact with their environments. Efforts to restrict the sale of small (less than 4-inch long) turtles have greatly reduced Salmonella infection rates in people in the US, but have come under continual pressure from the turtle breeding industry, and the regulation is often flaunted by pet stores and road-side turtle sellers.
From August 5 to September 26, 2011, 132 cases of Salmonella Paratyphi B infection were identified in 18 US states.
- The median age of infected individuals was 6 years, and 2/3 were less than 10 years of age. This is consistent with a pet-associated outbreak.
- 56 patients (and their families, presumably) were interviewed, and 64% of them reported turtle exposure. That's a lot higher than one would expect if a random sample of the general US population was surveyed, and suggests that turtles were an important source.
- Of the 15 people who could provide details about the turtle, 14 of them described turtles that would have been too small to be legally sold in the US. This isn't surprising, and shows both the risk associated with these small turtles and the fact that this law is being widely ignored.
- The same strain of Salmonella was isolated from turtle tank water in five homes (it's not clear if only five were tested or if there were some negative tanks too). That's further evidence implicating the turtles.
This is yet another reminder of the risks posed by small turtles, particularly to young kids. Small turtles have high Salmonella shedding rates, are easy to handle and are even small enough for kids to put in their mouths (yuck!). That's a bad combination.
In 2007, Louisiana turtle breeders sued to reverse the FDA's small turtle ban. Fortunately they weren't successful, however it's clear that the turtle ban needs to be enforced, but that's hard to do. Perhaps more important, then, is increasing public awareness of the risks. If people are better informed of the issues, they can make better decisions about acquiring pets and how to properly manage them. One such resource for the public is the Turtles fact sheet that we have freely available on the Worms & Germs Resources page.
Pasteurella multocida is a bacterium that's commonly found in the mouths of dogs and cats. It's a common cause of cat and dog bite infections in people, but can also be spread through close contact with pets (without bites). It's logical to assume that the closer the contact, the greater the risk of transmission. A recent report in Clinical Infectious Diseases (Myers et al 2012) describes three people with life-threatening Pasteurella infections. A unique aspect was all three people got sick from nursing dying pets.
- A 55-year-old woman with sore throat, fever and difficulty swallowing was diagnosed with epiglottitis (inflammation of the epiglottis, a part of the throat region) and hospitalized. Pasteurella multocida was identified on a blood culture. It was subsequently revealed that she had provided palliative care to her dying dog. As part of this, she was dropper-feeding the dog honey, and also eating honey with the dog from the same dropper.
- A 63-year-old woman with sore throat, difficulty swallowing and hoarseness was diagnosed with uvulitis (inflammation of a different part of the throat region) and narrowing of her airway. As with Case 1, P. multocida was isolated from her blood. Her cat had died six weeks earlier and she had "continuously held, caressed, hugged and kissed her cat during its last 7 days of life."
- A 66-year-old woman was hospitalized with fever, chills, cough and difficulty breathing. She had severe pneumonia and P. multocida was grown from a sample of respiratory secretions. Two weeks before she got sick, she had provided palliative care for her dying cat, by "holding, hugging, and kissing the head of the cat and allowing the cat to lick her hands and arms."
Fortunately all three women recovered from their infections, but the severity of disease is certainly a concern. As is common, there was no attempt to see whether the implicated pets actually carried the same Pasteurella multocida strain as the owners, but here the authors at least had a good excuse, since all of the pets had died before the owners got sick.
There are some interesting points in the Discussion section of the paper.
"Our 3 patients’ histories of having recently provided palliative pet care to their dying animals were obtained only after P. multocida was identified in cultures and only after subsequent detail-oriented, animal contact histories were obtained."
- Pet contact (or animal contact in general) is still not asked enough by physicians investigating unknown illnesses. It's unclear whether it would have made a difference in these cases, but knowing more and knowing it earlier can help speed the path to the right diagnosis. Here, pet contact was only considered after a pet-associated bacterium was identified.
"Simply asking whether or not the patient had a pet would not have uncovered the defined association of these respiratory illnesses with palliative pet care. The patient with P. multocida uvulitis even denied having a pet (it had died 6 weeks previously) and only admitted to having provided palliative pet care when asked specifically if she had any animal contacts in the past 3 months."
- This shows some of the challenges and how care must be taken when asking about pet contact. Simply asking "Do you have a pet?" doesn't cover it.
"Only diligence and very detail-oriented, pet-related histories will likely uncover further patients with invasive P. multocida infection related to the pet owner’s provision of palliative pet care to dying animals."
- This shouldn't be focused on palliative pet care, since that's a minor component of pet contact. Many other people have close contact with their pets, even when the pets are healthy. It's something that should be considered at all times.
While it shouldn't come as a surprise considering other studies, a recent study in PLoS One (O'Brien et al 2012) has caused a bit of a stir in the US. This study, headed up by Dr. Tara Smith's research group in Iowa, looked for methicillin-resistant Staphylococcus aureus (MRSA) in retail pork. They bought pork from different stores in Iowa, Minnesota and New Jersey, and tested it for the presence of MRSA. They focused on pork because MRSA can be found widely in pigs internationally, including in the US.
Not surprisingly, they found MRSA. Overall, they tested 395 pork samples from 36 stores, including both "conventional" pork (300 samples) and "alternative" pork (95 samples). The latter consisted of samples labelled "raised without antibiotics" or "raised without antibiotic growth promotants." MRSA was found in 6.6% of samples; 6.3% of conventional pork samples and 7.4% of alternative pork samples.
When they looked at the MRSA types that were present, 27% were the ST398 "livestock-associated" MRSA that's most commonly found in pigs. However, like our earlier Canadian studies, they found common "human-associated" MRSA strains more often. These strains can also be found in pigs, albeit less commonly than ST398, and it's unclear whether meat contamination with these strains comes from pigs or from people who handle the meat throughout the processing chain.
The fact that there was no difference between conventional and antibiotic-free pork isn't surprising to me, although it catches some people off-guard because of some basic over-assumptions about the relationship between antibiotics and MRSA in food animals. We can find MRSA quite commonly on both regular and antibiotic-free farms. While it's reasonable to assume that antibiotics were a key factor in driving the emergence of MRSA in pigs, there's not much evidence showing that ongoing antibiotic use is an important factor in determining whether MRSA is present on specific farms or in specific pigs. One potential explanation is that in order to control infections, farms that stop using antibiotics start using other substances such as zinc in feed to help control overgrowth of certain intestinal bacteria, and these compounds may be just as effective at selecting for certain resistant bugs as classical antibiotics. That's just one possible explanation, but it shows how complex the issue of antibiotic-resistance is, and it shows that simply saying "stop using antibiotics," without really looking at the overall problem, won't necessarily reduce MRSA.
What does the presence of MRSA in food mean? Who knows? MRSA is a pretty high profile bug, and with good reason, because it's a very important cause of infection in people. A key aspect of MRSA in food is that cooking food will kill the bacteria (as well as many of the other harmful bacteria that often contaminate raw meat). So proper attention to food safety, including thorough cooking, cleaning of surfaces, prevention of cross-contamination and hand hygiene, should greatly reduce any risk (the problem is a lot of these things aren't usually done very well).
Although the weather in Southwestern Ontario seems quite confused lately regarding whether it wants to be winter or spring, at least we're still a few months off from having to worry about mosquitoes and the viruses they carry once again. Warmer parts of the world, however, are in the midst of their mosquito season, and some chickens are lending a hand to give people in the area a "heads up" about what's around.
The Health Department of Western Australia has detected Murray Valley encephalitis virus (MVEV) in chicken flocks in East Kimberley. The department has also tested and found the virus in its sentinel chickens in Wyndham and Kununurra. These sentinel birds play an important role as an early warning system when viruses like MVEV are circulating in the area. Just like West Nile virus, MVEV typically circulates between birds and the mosquitoes that like to feed on them, but problems occur when the same mosquitoes start to bite people (or other susceptible animals such as horses), particularly when there are a lot of mosquitoes, like when the weather is very wet or when there's been flooding. Although most people who are infected with MVEV or WNV fight off the virus with no difficulty, or may simply develop short-term, non-specific signs of illness like mild fever and malaise, in some people these viruses can cause severe infection of the brain (encephalitis) and may even be fatal.
Knowing that MVEV has been found in these "guardian" chickens lets people know (via warnings issued by the health department) to take extra precautions against mosquito bites, such as:
- Staying indoors during peak mosquito activity - dusk and dawn
- Wearing protective clothing including long-sleeves and long pants
- Applying insect repellent
In North America, you can pretty much substitute West Nile for Murray Valley in a case like this. Sentinel chickens have been used to provide early warnings of circulating WNV here, before cases are detected in people or horses. Another means of early detection that is also used is testing pools of mosquitoes directly.
It just goes to show you can still be an important part of the country's defenses, even if you're a little chicken :p
No, not gravy made from bearded dragons (a type of reptile), but foodborne Salmonella with a link to the reptile.
Reptiles are an important source of Salmonella, which is why standard guidelines recommend that high-risk people (e.g. children less than 5 years of age, elderly individuals, people with compromised immune systems, pregnant women) not have contact with reptiles or have them in the house. A report in Zoonoses and Public Health (Lowther et al 2011) highlights another possible risk.
The report describes a Salmonella outbreak that was traced back to a potluck dinner. Nineteen cases were identified, 17 primary cases (people that attended the dinner) and two secondary cases (household members of people that attended the dinner). Overall, 29% of people that attended the dinner got sick. A further 18 people had some intestinal disease but strictly speaking didn't fit the definition for a case (however it is suspected that they were part of the outbreak). Salmonella subspecies IV (a type mainly associated with reptiles) was isolated from the stool of five people, confirming the occurrence of an outbreak.
As is typical, food consumption history was evaluated. Sixteen of the 17 primary cases reported consuming turkey gravy, which was a statistically higher proportion than that of people who did not get sick. The gravy was made at the private home of a person who didn't attend the dinner. This was the only home of the people involved where reptiles were kept. Two healthy bearded dragons lived in the house, in a terrarium in the living room.
The investigation focused on the reptiles, since the Salmonella strain found is typically associated with reptiles, and the turkey (the source of the gravy) had no evidence of Salmonella contamination based on testing. Samples from the environment of the household where the gravy was made were collected, and two types of Salmonella were identified. One of these Salmonella types (Salmonella Labadi, which was different from the outbreak strain) was isolated from one of the bearded dragons, as well as the inside and outside of the terrarium glass, other terrarium surfaces, surfaces around the terrarium, the bathroom sink drain and kitchen sink drain.
A common question that comes up when people have reptiles and high risk people in the house is "If I don't take the critter out of the cage, I should be ok, right?" Unfortunately, that's not true. Human Salmonella infections have been clearly identified in situations where reptiles don't leave the terrarium because (as was the case here), while the reptile may not leave the terrarium, Salmonella often does.
The person who made the gravy said that the bearded dragons had not been out of the terrarium when food was being prepared. A child was responsible for feeding the reptiles and cleaning the terrarium, and was supposed to use the bathroom for terrarium cleaning. However, it was reported that the reptiles' dishes "might have" been cleaned in the kitchen sink during the the day period when food was being prepared for the party.
The overall conclusion was that this outbreak "probably resulted from environmental contamination from bearded dragon faeces." It's a reasonable conclusion. Even though the same Salmonella strain wasn't found in the reptile, it makes sense because the reptiles were the most likely source of environmental contamination in the household, and that was the most likely source of the foodborne contamination. Reptiles can shed various Salmonella strains and they can shed intermittently. It takes multiple samples over time to get a real idea of the scope of Salmonella shedding, and I assume that one or both of these reptiles were shedding the outbreak strain at some point.
How can something like this be prevented, since the standard recommendation of having high risk people avoid contact with reptiles doesn't apply to this type of situation?
- Good hygiene practices should be used when handling reptiles and their environments. In particular, there should be proper attention to hand hygiene after contact with reptiles or their cages.
- Reptiles should not be allowed in the kitchen. Ever.
- Food and water bowls should not be cleaned in kitchen sinks. Terrariums should not be cleaned in kitchen sinks. Ideally, they shouldn't be cleaned in bathroom sinks either. (If possible they should be cleaned outdoors with a hose.)
- Good food handling practices are critical. Here, gravy wasn't re-heated to a high enough temperature to kill the contaminating Salmonella. Adequate re-heating would have prevented this outbreak.
The Redlands Animal Shelter in California is looking into bird control measures after blaming Giardia infections in dogs on exposure to wild bird poop. On Facebook, Redlands Friends of Shelter Animals have declared "We have a serious problem with birds at the shelter. They land on the kennels and poop goes into the water bowls and give the dogs giardia - which is a parasite that gives them explosive diarrhea."
Giardia is a protozoal parasite that can cause diarrhea in dogs and other species. It can also be carried by healthy dogs, at relatively high rates in some groups. The scope of the problem at the Redlands shelter isn't clear since the news article only talks about one case. Whatever the scope, shelter management is blaming the birds.
Apparently, discussions are underway with different companies about a solution to the bird problem, something that is anticipated to be expensive. However, it's all too common for people to jump the gun on expensive interventions when there's an outbreak and overlook the root causes. While news reports don't always give the whole story, I'd be wary about blaming birds without much more evidence.
Can wild birds carry Giardia? Yes. However, there's more to the Giardia story than that. It doesn't sound like they've actually tested the bird feces to determine whether Giardia is there. Additionally (and critically) it doesn't sound like they've determined the type of Giardia that's infecting the dogs. There are different types (assemblages) of Giardia and most have a limited range of species they can infect. The vast majority of dogs with Giardia in most regions are infected by Assemblage D, a dog-specific strain that comes from other dogs and poses no risk to people. I'm not aware of Assemblage D being found in birds. Dogs can also be infected by Assemblage A, a type that infects people, and also can infect birds.
So, if Assemblage D is involved, they need to look at transmission between dogs within the shelter. If Assemblage A is involved, they still need to focus on dogs but could investigate birds as a potential source.
Overall, Giardia transmission is much more likely due to breakdowns in cleaning, disinfection, hand hygiene and general shelter practices rather than birds pooping in water bowls. It's a lot cheaper to address these shelter management practices (which will also help control various other infectious diseases) rather than dumping a lot of money into controlling bird exposure when in fact that may not be causing the problem. Trying to reduce exposure to bird poop is a good thing as a general practice, but it's important to focus efforts and resources on finding and addressing the true root problems during an outbreak.
More information about Giardia can be found on the Worms & Germs Resources page.
The unfortunate victim was a 73-year-old Haitian women. She initially went to an emergency room with a complaint of right shoulder pain, chest pain, headaches and high blood pressure. Difficulty swallowing was also noted when she was given pain medications, but she declined further testing and was discharged. It's not surprising that rabies wasn't considered at this point, although I doubt she was asked about animal contact or animal bites as a routine history question.
The next day, the woman went to two different emergency rooms, complaining of shortness of breath, spasms, hallucinations and balance problems. A cause was still not readily apparent, and over the next couple of days, her condition deteriorated, with development of more neurological abnormalities including tremors and mild seizures. Encephalitis (inflammation of the brain) was diagnosed, and a range of potential causes were ruled out. A nuchal skin biospy was collected for rabies testing but she was declared brain dead by the time results were obtained.
The strain of rabies that was identified most closely matched a canine rabies virus variant from a person in Florida who acquired rabies in 2004 while in Haiti. Upon further investigation, a cousin recalled that the person had been bitten by a dog in Haiti a few months earlier. The bite wasn't considered severe and medical attention wasn't sought.
As an almost invariably fatal infection but an almost completely preventable disease with proper medical care, education is a key aspect of rabies control, and that's where most of the breakdowns occur. This person didn't seek medical attention after the bite, because the bite wasn't too severe. Unfortunately, mild bites can transfer rabies just like severe bites, and any bite needs to be investigated as a potential source of rabies, particularly in highly endemic areas.
Canine rabies is a major problem internationally, accounting for tens of thousands of human deaths each year. Canine rabies has been eradicated in the US, meaning the canine rabies virus strain is no longer circulating. That doesn't mean dogs in the US can't get rabies, since they can be infected with various wildlife strains, but there is not a circulating pool of canine rabies virus like in some other regions. Canine rabies is still endemic in Haiti, although there have been efforts to control it through education and vaccination of dogs and cats in the country (where less than 50% of dogs and cats are vaccinated).
People living and traveling to rabies-endemic regions like Haiti need to be aware of the potential risk of rabies and consider any dog bite a possible rabies exposure. Similarly, healthcare workers need to query animal exposure and animal bites as a routine practice, since as with this case, rabies can be hard to diagnose initially.
Following on the heels of a case of bat-associated rabies in a South Carolina woman, a Massachusetts man has contracted rabies. Little information is currently available, although authorities state that they believe he was exposed by a bat in his home. News reports state that he's in critical condition but it's unfortunately very unlikely that he'll survive. Family members are receiving post-exposure treatment, however it's unclear whether this is because of concern for exposure from the infected man, or from the bat.
While these two cases don't represent a rampant rabies epidemic, it shows that there is still a long way to go with education of the public about bats and rabies. Rabies is a disease of extremes. It is essentially 100% preventable in people if exposure is identified and managed properly. It's also almost invariable fatal once disease sets in.
It seems like pet bite articles come in waves, with a recent cluster showing the variable quality in advice that's available.
Often, they are holiday "filler" articles that provide some basic useful information but overall are of limited use or even harmful based on their very superficial approach. They often mention rabies, get a quick quote from a veterinarian or someone in public health, but don't emphasize the potential problems that can occur with even apparently minor bites. The thing that often raises my ire is the common statement about watching the bite and going to a doctor if your limb swells up or has pus oozing out, without talking about the need for proper post-bite care to actually prevent that from happening.
Anyway, I came across a couple of better articles recently, that get some good information across in a nice, readable manner. One, an article in "The Herald News" entitled "Cat bites always require check by doctor", gets a very important point across quickly.
The news story details the saga of the PJ, a 13-year-old cat, and his owner. PJ bit the woman on the arm causing a seemingly minor wound, but by the next day, her arm was red and swollen, necessitating a round of intravenous antibiotics and four days in hospital. In the article, Gail Steele, an infection prevention nurse, states "Cat bites.. must always be considered medical emergencies. This is especially true when they occur in the hand because that area has a richer blood supply...Their sharp little teeth are like little needles, and they inject bacteria right into soft tissue..."
This is a pretty extreme example of what can happen after a cat bite, but it's far from rare. It's not really clear whether this person's infection would have been prevented with normal practices. Bites over certain sites, like the hand, foot, joints, tendon sheaths and prosthetic devices, and bites to young kids, elderly individuals and people with compromised immune systems typically require prophylactic antibiotics.
If this was actually a bite over the arm, as reported, antibiotics might not have been given, even though cat bites are much higher risk for infection than dog bites. However, the key is that bites should be assessed so proper determination can be made about the need for antibiotics. All infections won't be prevented but appropriate medical care should reduce the risk and also allow for adequate consideration of whether rabies exposure might be a concern.
There's a sad end to this article, as PJ bit his owner again a few months later. The bite was over the shin and, given her previous problems, antibiotics were provided. However, the owner still ended up with an abscess that required surgical intervention and took months to heal. (Whether this person has really bad luck, whether PJ has a particularly bad mix of bugs in his mouth or whether the owner has an unidentified problem with her immune system is unclear, but back-to-back severe infections is a major issue, especially with a cat that is prone to biting.) The woman's daughter ended up taking PJ home with her, but after another unprovoked bite, he was euthanized.
Cat bites aren't always this bad, and in fact, most don't result in complications. However, that's not to downplay the potential problems. When you consider how often cats bite, how often cat bites are not properly cared for because they appear to be minor, and the ability of a cat bite to inoculate bacteria deep into the tissues, it's easy to see how bad things can happen. Reducing the risk of cat bite infections involves a few basic steps:
- Reducing bites. Good handling and training (of both cats and people) can reduce the likelihood of bites. This is particularly important with kids, who may be bitten through rough or excessive handling of a cat.
- Bite first aid. Prompt cleaning of the wound can reduce bacterial contamination. Thorough cleaning with soap and water can have a big impact on the likelihood of infection.
- Medical care. Bites over certain sites or to certain individuals (see above) almost always require antibiotics. There's less consensus over other types of bites, but getting medical care is a good idea in any case to determine if there are any factors that indicate a need for antibiotics.
- Rabies avoidance. Every bite should be reported to public health so the rabies aspect can be covered. The biting animal needs to be identified and observed for 10 days. If it's healthy after 10 days, it couldn't have been shedding rabies virus. If the biting animal cannot be identified, it's likely that post-exposure treatment for rabies will be required.
Marion County (Florida) public health personnel recently issued a rabies alert after a horse in the area tested positive for the virus. It’s a standard alert, emphasizing avoiding contact with wildlife, reducing things that attract wildlife to houses (e.g. accessible pet food or garbage) and recommending vaccination. Interestingly, while this alert was prompted by a case of rabies in a horse, it only mentions vaccination of dogs, cats and ferrets. That may have been because it was an off-the-shelf alert, not really tailored to this situation, but it shows how horses can be overlooked when it comes to rabies.
Fortunately, rabies is a rare disease in horses. In 2010, there were 37 reported cases of equine rabies in the US and only one in Canada (two Canadian cases have been identified so far this year). That’s a very low rate, especially considering the number of horses out there, but it’s still more cases than there should be for a very serious yet highly preventable disease.
Unfortunately, rarity sometimes breeds complacency, so despite the fact that rabies is invariably fatal in horses and rabid horses pose a risk to people, vaccination of horses is often overlooked. While rabies is rare in horses, rabies vaccination shouldn’t be rare. Every horse in a rabies endemic region (or that might be traveling to such a region) should be vaccinated against rabies. It’s cheap insurance against a very dangerous and deadly disease.
A South Carolina woman has been identified as the first case of human rabies in the state in the past 50 years. Very little information has been released, including whether or not she is still alive. Unfortunately, the odds are quite low that she survived. Successful treatment of a Wisconsin girl in 2004 using a radical new protocol was accompanied by much optimism for treatment of this disease, which at the time was described as invariably fatal. While a few other survivors have been reported, rabies is now often referred to as almost invariably fatal, since the protocol has not been the panacea that it was hoped to be, and death is still the typical outcome.
In the latest case, exposure to a bat in the home a few months earlier was the suspected source of infection. This is a common source of exposure and a typical time frame. Few details are presented, so it's not clear whether the woman was known to have been bitten by the bat or whether that's suspected for some other reason (such as lack of other possible sources).
This is another indication of the care that needs to be taken around bats. While human rabies is fortunately very rare in Canada and the US (it causes tens of thousands of deaths each year worldwide, mainly from dogs in a few developing countries), bats are an important source of exposure. Any encounter with a bat needs to be accompanied by a determination of whether there is a risk of rabies exposure. Anyone bitten by a bat should try to make sure the bat is caught and tested for rabies, because otherwise there's no way to prove it wasn't rabid, and post-exposure treatment would be indicated.
Image: Bat bites can be very dangerous, because they carry the risk of rabies transmission, but they can be so small that they may not even be detected. (Image source: http://agrilife.org/batsinschools/responding-to-a-bat-bite/)
Pigeon fever is an equine disease that doesn't have anything to do with pigeons. It's an infection caused by the bacterium Corynebacterium pseudotuberculosis which results in the formation of abscesses, usually along the chest (pectoral region) and lowest part of the abdomen. The name "pigeon fever" comes from the swelling in the chest region that vaguely resembles a pigeon-breast. A recent report describes and outbreak of pigeon fever involving at least 30 horses in Louisiana, bringing the estimated number of cases in the state in 2011 to over 100.
Pigeon fever is a regionally (and to a lesser degree seasonally) variable disease. It predominantly occurs in California, but over recent years it has expanded its range in the western US, and from this report, it's obvious that it has a good foothold in some other areas in the south east as well.
Corynebacterium pseudotuberculosis lives in the soil, and causes infections in horses when it gets inoculated under the skin via wounds and perhaps sometimes through fly bites. Once it gets into the tissues, it starts to grow and causes painful (and potentially large) abscesses that often need to be surgically incised in order to drain them.
Infection control practices on farms can help reduce transmission of the bacterium between horses and to reduce the risk of injuries. These include:
- Quarantine of new arrivals and careful inspection for sign of infection.
- Isolation of known infected horses.
- Use of "contact precautions" when dealing with infected horses to prevent transmission of the bacterium via peoples' bodies or clothing. This involves the use of protective outwear (e.g. coveralls and boots that are only used for the infected horse(s)) and gloves.
- Proper use of handwashing / hand sanitizer by people handling infected horses (or any horses, really, from a broader standpoint).
- Prevention of cross-use of items like buckets between infected/quarantined horses and the general horse population.
- Use of fly repellent, especially on horses with open wounds or draining abscesses.
- Careful cleaning and disinfection of areas potentially contaminated by pus from draining abscesses.
- Inspection of stalls, paddocks and fields for things that could cause wounds that might subsequently become infected.
Pigeon fever is a good example of why it's important to know disease patterns in your region (and those to where your horses travel). Being aware of the possibility of a specific disease is an important step in diagnosis, and knowing there is disease activity in any area in which your horse may have been is a key part of that. This disease is also an example of why we need ongoing disease surveillance and reporting, because if a disease makes it into new regions, veterinarians and horse owners need to know about that as soon as possible to allow for quicker diagnosis and use of control measures. Unfortunately, organized disease surveillance and communication is sorely lacking in horses.
Photo: A Jiennense Pouter Pigeon, which has a very pronounced breast compared to other breeds. The swelling of a horse's pectoral region due to abscesses caused by C. pseudotuberculosis is the reason the disease is sometimes called "pigeon fever." (click image for source)
Today's Morbidity and Mortality Weekly Reports, published by the CDC, describes Campylobacter jejuni infection in two men. Campylobacter is a zoonotic bacterium that causes diarrhea (and sometime severe complications) in people after it's ingested. It's usually a foodborne disease, but any method that leads to the bacterium reaching the mouth and being swallowed can result in to infection. This report describes a rather unusual method of infection.
This summer, the Wyoming Department of Health investigated two cases of C. jejuni infection. Both people worked on a local sheep ranch and got sick at the same time. Both had typical campylobacteriosis disease with diarrhea, cramps, fever, nausea and vomiting. One was hospitalized but both recovered. The interesting part is how they got infected. It turns out the men were involved in a multiday "event" to castrate and dock tails of 1600 lambs. Ten other people were also involved and they didn't get sick. The difference between these two and the other ten? The two infected men used their teeth to castrate some of the lambs. Animal welfare issues aside, this is just stupid. (I doubt anyone's looking at this but these idiots shouldn't be allowed to care for animals.) I don't see how anyone with an iota of common sense wouldn't think this is a bad idea in the current day and age. A very long time ago, apparently the "bit and spit" technique of castrating lambs (see photo, click for source) was relatively common practice. But like so many things that people used to do, there are much better (and safer, and infinitely more hygienic) ways of doing this nowadays.
Hopefully, they learned their lesson. Additionally, hopefully the farm owner takes some responsibility to make sure their personnel don't act like idiots and that someone investigates the animal cruelty aspect.
Photo: In "the old days" during castration of lambs, after opening the scrotal sac with a sharp blade, the testicles were often removed using the teeth, because it was faster than attempting to do so with an instrument. This technique is (almost) no longer practiced (except for at least two men in Wyoming, apparently). Photo source: http://old-photos.blogspot.com (used with permission)
The Toronto Star has an article describing the efforts of Naz Sayani to bring home a group of street dogs from India. As an animal lover, she was touched by the number of stray dogs roaming around New Delhi while accompanying her daughter to India for medical treatment. She borrowed a car and started driving around the city dropping off food for strays.
- This is a high-risk activity for rabies exposure. Rabies is very common in India and contact with strays is a prime source of human infection. Ideally, anyone working with strays should be vaccinated against rabies. At a minimum, they should be aware of the risk and be ready to get post-exposure treatment if exposed (possibly through a quick trip out of the country, since knowledge about rabies prevention and access to rabies post-exposure treatment is variable in India).
A pregnant stray dog caught Naz's eye, and after hearing about people threatening or abusing the dog (and later her and her pups), she tried unsuccessfully to find them homes. Eventually, she made the decision to bring them to Canada, in order to try to find homes for them here.
I can certainly see how this would happen, as it's easy for people to get attached to a friendly, needy animal. It's also hard to balance a case-based scenario like this, when someone has an attachment to a specific animal, with the bigger picture of animal rescues, and all the associated pros and cons.
I get a surprising number of advice calls and emails from people "rescuing" dogs from various places.
- The typical questions goes something like "I am organizing a rescue of a group of dogs from [insert one of many central or southern US states here] and want to know if there are any infectious disease issues I have to worry about".
- Worse are the calls that go "I just got some rescue dogs from [wherever] and now my other dogs are sick. What might be going on?"
People that are rescuing dogs usually do it because they have big hearts. Some people like the "status" that they see attached to certain rescue dogs ("You have a new Mercedes? Well I have a new Hurricane Katrina rescue dog"). My problem with international rescue efforts is the question of a) whether it's a good use of resources and b) whether it poses unnecessary infectious disease risks to people and other animals.
- Organizing rescues, fulfilling regulatory rules, shipping dogs and finding them homes takes a lot of money. It would make more sense if there was a shortage of adoptable strays in Ontario. However, I haven't heard any shelter personnel lament their lack of dogs, undercrowded facilities or excessive financial resources.
- Moving animals between different regions carries an inherent risk of transmission of infectious diseases. The more movement, the more mixing and the greater the difference in infectious diseases in the areas, the greater the risk of making more animals sick, and potentially doing more harm than good.
- Rabies is one concern, and rabid dogs have been imported into North America in the past. Since rabies has a long incubation period, it's hard to be certain that a dog's not incubating a rabies infection.
- More likely to be imported would be a wide range of other bacteria, viruses, parasites and fungi. These are a concern from several standpoints. Some might cause disease in the imported animal, and diagnosis may be delayed or missed because of it being a disease with which local veterinarians have no experience. Some might bring an unusual pathogen into the area that could be spread to a few other in-contact dogs. Worse, some might bring in a new pathogen that could then establish itself in the local (or national) dog population. We don't know how often any of these scenarios occur, but they are always a risk, and need to be part of the cost-benefit analysis of animal rescue operations and associated animal importation.
At the end of the day, it's hard for me to support rescuing dogs from other regions when we already have a large population of dogs in our own shelters and animal being euthanized here because there are no homes for them. I can't justify the expense and risk of importing dogs if, for every new dog imported, one other dog in a local shelter gets euthanized because it doesn't have a home. Does importation really mean fewer adoptions here? We don't know, but it stands to reason.
A situation like this is a little different, as a chance and presumably (hopefully) one-time event prompted by a specific human-animal bond. Overall though, we could do better for the dog populations both here and in regions where there are massive stray problems by focusing attention on better care and adoption here, and international programs aimed at helping stray populations abroad through vaccination, education and sterilization efforts.
Staphylococcus schleiferi doesn't get much respect. Most of the attention gets paid to Staphylococcus aureus (because MRSA, the methicillin-resistant version, is such a high profile pathogen in humans and it can be transmitted between people and pets) and S. pseudintermedius (because it's a leading cause of infection and MRSP, the methicillin-resistant type, is spreading very quickly and widely in dogs).
Staphylococcus schleiferi is another Staphylococcus species that can cause various infections in dogs, particularly skin and ear infections. It's often overlooked, or more specifically, unnoticed. The problem is it takes some effort to differentiate it from other staph. This species is relatively unique in that it has two distinct subtypes - S. schleiferi coagulans and S. schleiferi schleiferi. The first one is very similar to S. pseudintermedius, and not all diagnostic labs go through the trouble of trying to distinguish one from the other. So there may actually be a lot of S. schleiferi infections that get mistakenly diagnosed as S. pseudintermedius. The second subtype is coagulase-negative (whereas S. pseudintermidius, S. aureus the first subtype of S. schleiferi are all coagulase-positive) and most diagnostic labs don't do any identification of coagulase negative staph. As a result, we only have a superficial understanding of it and its epidemiology.
A recent study from the University of Pennsylvania (Cain et al., J Am Vet Med Assoc 2011) that looked at 225 dogs with S. schleiferi infections has provided some insight into this perhaps not-so-unusual bug. Some highlights:
Ear infections and skin infections accounted for 87% of cases.
- That's expected, since these are very common types of infections for any kind of staph.
Allergic skin disease was the most common underlying disease.
- That's also not surprising. Most staph infections occur secondary to some underlying problem or procedure (e.g. surgery). This shows the importance of taking the time and effort to diagnoses and control allergic skin disease, in order to help prevent infections before they occur.
57% of S. schleiferi isolates were methicillin-resistant.
- Ugh! I'm not very surprised but it's scary how often we see methicillin-resistance in some staphylococci, because of the complications it can cause with treatment. Methicillin-resistant staph infections can be hard to treat because there may be few effective antimicrobials available.
Methicillin-resistance was more common in the coagulase negative subspecies, S. schleiferi schleiferi.
- It's hard to say whether this means a lot from a clinical standpoint. In generally, coagulase negative staph are much less of a concern than the coagulase positive staph since they are less likely to cause disease. However, we don't really understand the differences between the two S. schleiferi's. If the coagulase-negative version is less able to cause disease, then a lower rate of methicillin resistance in the more concerning coagulase positive type is better than vice versa, but I'm not sure we have enough evidence to say much about this at the moment.
Treatment with a penicillin (e.g. amoxicillin), first generation cephalosporin (e.g. cephalexin) or 3rd generation cephalosporin within the preceding 30 days was associated with having methicillin-resistant S. schleiferi.
- That's not surprising and is one more piece of evidence that "routine" use of antibiotics can contribute to selection for methicillin-resistant staph. It shows how we need to focus on prudent use of antibiotics.
A question I sometimes get is whether an animal with methicillin-resistant S. schleiferi poses a risk to people. We don't really know, but the risk is probably quite limited.
- S. schleiferi coagulans infections in people are extremely rare, so this bug doesn't seem to have much of an affinity for humans.
- S. schleiferi schleiferi infections in people are more common, but it is thought that this subtype is a "human Staphylococcus." Therefore, while it can cause infections in people (usually infections in people that are already sick and/or in hospital), it probably comes from people, not animals.
- So, overall, the risk posed by infected animals is minimal. However, some S. schleiferi can be very drug resistant and you don't really want to have an infection with a multidrug resistant bacterium of any kind ("you're case is very unique" isn't something you want to hear from your doctor), so using good general infection control and hygiene practices around infected dogs makes sense.
As MRSA in animals gets more attention, there have been increasing efforts to develop guidelines to reduce the incidence and impact of this important zoonotic pathogen. Among these are a set of recommendations developed in Finland for the prevention and control of MRSA infections in animals (or metisilliiniresistentti Staphylococcus aureus, as they would say in Finnish). Apart from the abstract which is translated into English, the document is entirely in Finnish, but it might be of interest to any of our readers that are proficient in that language (presumably a pretty small subset). This is clearly a worldwide issue, and it's important that it is addressed on a worldwide basis.
The scope of research that's being done these days is astounding. Somewhere, someone's working on a project that will lead to a Nobel Prize in medicine. Other research will gather less critical acclaim but still have a big impact on science. Some research is more basic but can result in important preliminary information. And some studies... well, they may have a serious side but they're not what people typically think about when envisioning medical research.
Here are a few highlights from the lesser-heralded group of people investigating bathroom behaviours:
- A study of toilet reading habits in Israeli adults (Goldstein et al. Neurogastroenterol Motil 2009) concluded that toilet reading is a common and benign habit. (I hadn't really thought of it as a potentially poor lifestyle choice, but I guess this confirms it's fine). While it involves more time spent in the bathroom, "It seems to be more for fun and not necessarily to solve or due to medical problems." (Perhaps a more relevant area of study would be hand hygiene practices by toilet readers and the impact of toilet reading on fecal contamination of reading materials.)
- A Korean group has established that frequent recreational cycling does not have a negative impact on urination or sexual function in men (Kim et al. Korean Journal of Urology 2011). Cycling enthusiasts around the world, including me, rejoice.
- Horseback riders can be similarly relieved (pardon the pun) that recreational riding isn't associated with increased risk urinary or sexual dysfunction (Alanee et al. Urology 2009).
- A study with the catchy title "Female bowel function: the real story" (Zutshi et al Dis Colon Rectum 2007) wasn't too thrilling but had tidbits such as older women and women with children report more flatulence.
What do these have to do with zoonotic or infectious diseases? Nothing, but a little potty humour lightens up the start of the work day. More "real" posts to follow.
One of the big doomsday scenarios of the past couple of decades has been an H5N1 avian influenza pandemic. Human infections with this virus have occurred in various parts of the world (mainly southeast Asia) and death rates are quite scarey (50% or higher). Fortunately, the virus does not transmit efficiently between people, so human cases are linked to contact with infected birds or very close contact with infected people, and the current form of the virus is unlikely to have a wide impact on people. The concern is that if this virus changes to become readily transmissible between people, like common human influenza viruses, then a pandemic similar to the devastating Spanish flu outbreak of 1918 could occur (see image).
This raises the question: Should researchers be tinkering with H5N1 to see what mutations make it more transmissible? Those in favour want to understand more about the virus and what has to happen for it to become more infectious, but obviously there are considerable risks involved and others think this is playing with fire. This debate has reached full swing following a report by a Dutch researcher at the 2011 ESWI Influenza conference describing lab-induced mutation of avian influenza virus to make it highly contagious between ferrets. Ferrets respond similarly to influenza viruses compared to people, so something that spreads quickly between ferrets probably also spreads quickly between people. Therefore, the researchers may have (rather easily, it turns out) already created the ultimate "superbug."
So, is this good or bad?
- This type of research provides more insight into avian influenza and gives us more of an idea of what has to happen for the virus to become more transmissible. This may help determine whether there's a realistic concern of this happening in nature, and also provide more general information about influenza viruses.
- Is it responsible to create something like this that could kill millions if it gets out of the lab, either accidentally or maliciously? We have enough serious infectious disease threats already - do we need to be making more?
- Is publishing information like this just providing a recipe for bioterrorists? Manipulation of microorganisms can be done quite easily by people with some training and equipment. Materials are a lot easier to access than for other potential weapons of mass destruction. Do we want to make it easier by publishing step-by-step instructions?
The research findings haven't been published, and they are being scrutinized by an independent committee (set up by the US government) that provides advice about situations like this where legitimate research might be used for nefarious purposes. The committee makes non-binding recommendations, but presumably those recommendations would carry a lot of weight if publication is being considered.
This is a complex area. Academic freedom to pursue scientific investigations is very important and has helped modern science advance as quickly as it has. However, it's hard to determine where the benefits of individual academic freedom are outweighed by the risk to society from information developed in those academic pursuits.
Image: Historical photo of the 1918 Spanish influenza ward at Camp Funston, Kansas (where the pandemic began), showing the many patients ill with the flu. (US Army Photographer, 1918)
CTV has a consumer reports segment and a recent topic involved feeding pets "natural" diets (although no one ever defined what that really means). In the report on the CTV Consumer Alert website (it's currently about the third story into the video if you just press play, or you can shortcut to it using the link below the main video window), a 26 year old cat is held up as a poster child for the health benefits of raw food. Making it to 26 is a noteworthy accomplishment for a cat, but it's far from rare, and you can't know whether the cat survived because of its diet or despite its diet. At the end of the clip, they mention he cat has kidney disease, not an uncommon problem in older cats but one that is often blamed by raw proponents on commercial foods. It's also not a condition that I'd want to see someone try to manage with a raw diet.
Anyway, the story has the typical statements (including one from a veterinarian) about how raw and "natural" diets produce a healthier animal, stronger immune system and shinier haircoat, but without citing any proof (because there is none) and with no discussion whatsoever about the potential animal and public health impacts of raw meat feeding.
Good investigations are good. Quick reports put together with little thought or consideration of the issues are just time filler. The host, Pat Foran, said in his conclusion that "natural" pet foods have less filler so there's less to come out the back end of the dog. Well, news reports comprised of filler produce the same kind of by-product.
If you are going to feed raw, at least take the time to research how to do it safely, both for your pet and your household. Raw feeding can be done in a nutritionally sound manner, but it takes time, effort and money. Some people are willing and able to do that, but if you're not, don't feed raw. Raw feeding also carries some risk of gastrointestinal disease like salmonellosis in the animal as well as exposure of people in the household to those same bugs. Certain households, particularly those with high risk individuals (e.g. elderly, infants, pregnant women, immunocompromised persons) should avoid raw feeding or only use products that have been high pressure pasteurized. There are a few commercial raw diets that are treated in this manner and these are preferable as the process should kill most relevant bacteria, reducing or eliminating the infectious disease risks to pets and people.
Like many other things in life, the key is being informed so you understand the risks and benefits, and whether recommendations made by people have any substance behind them. Too often, people make a major change like feeding raw based on a comment on a website or from another dog owner, with no clue about the issues and no effort to figure out how to do it right. That's just asking for problems.
More information about raw diets can be found on the Worms & Germs Resources page.
A Kitchener, Ontario family is dealing with a household outbreak of ringworm, likely contracted from a new pet guinea pig. Ringworm is a fungal infection cause by a few different types of fungi. Some ringworm fungi are able to infect both people and animals, and those can be spread in households from direct contact with an infected person or pet. In this case, the Gross family purchased a new guinea pig from a local pet store, and unfortunately, ended up bringing ringworm home as a bonus.
As is common, the new pet was the centre of attention when it got home, and the Gross' three children, ages 8, 5, and 2, had very close and frequent contact with it. The next day, the family noticed an area of hair loss on the guinea pig, at which point they took it back to the store. Ringworm was subsequently diagnosed, though there's no mention of how this was done, nor is there any mention of what actually happened to the little critter afterward.
The big problems started a week later, when a red lesion was seen on their youngest child's back. This was also diagnosed as ringworm, though again there's no mention of how, or whether it was definitively confirmed as ringworm. The newspaper report goes on to say "More spots kept appearing on Matthew’s skin as Gross was given different steroid creams to try and contain the infection." You always need to take media descriptions of medical issues with a grain of salt. Hopefully, the child was treated with anti-fungal cream, not steroid cream, as the latter not only won't treat ringworm, they may make it worse if used alone. Steroid creams are often prescribed for non-specific skin issues (particularly if the skin is very itchy, which can certainly happen with ringworm), but in a case like this where there was known contact with an animal with ringworm, I have to hope that the physician was treating with an antifungal cream instead of, or in addition to, a steroid cream.
Anyway, whether despite or because of the treatment, more skin lesions kept appearing on the child. Then skin lesions were found on the family dog, and both the dog and cat ended up being treated for ringworm. The treatment for dogs and cats is relatively straightforward, but it's still a hassle and can be somewhat expensive, and often takes several weeks.
The family has contacted the pet store about paying for cleaning supplies, air purifiers and veterinary bills, but the company did not respond to the newspaper reporter's inquiries, citing an ongoing investigation. It's hard to say whether the company should be held responsible. It largely depends on the measures they take to reduce the risk that they are selling pets at increased risk of transmitting infectious diseases. There's always a chance of picking up something from a pet, so an infection does not necessarily indicate incompetence or liability. If a store had reasonable practices in place, it's probably the purchaser's responsibility to take proper precautions when they take the pet home, and it's an example of why prompt veterinary examination of new pets is always a good idea. It's rarely done, particularly for species that cost less than the price of a veterinary exam, and you never know whether it would have helped prevent anything in this case, but in many instances it can help identify potential issues and address them before problems occur.
Preventing outbreaks like this can be difficult. Ringworm can be found on animals in the absence of any skin disease, so you can't always tell an animal is infected by looking at it. (However, in this case if a large patch of hair loss was noticed by the owners the day after the guinea pig came home, it's likely that something was evident the day before). Ringworm is spread by direct contact, which is common between pets and kids, especially new pets that often get smothered with attention in the first few days. Good hygiene practices, particularly attention to handwashing, can certainly help, but some degree of risk will remain.
Overall, guinea pigs are relatively low risk for zoonotic diseases, but this report shows that even "low risk" pets can be sources of infection. Fortunately, while controlling ringworm outbreaks can take time and be frustrating, it's not a serious disease and it is controllable.
More information about ringworm can be found on the Worms & Germs Resources page.
Veterinarians at Michigan State University's College of Veterinary Medicine are warning of an upswing in leptospirosis in dogs in the Detroit area. More than 20 cases of leptospirosis have been reported in dogs in the Detroit area, and it's likely that many more unreported cases have occurred. Leptospirosis, a bacterial infection, can cause very serious disease, including potentially fatal renal failure. It can be vague and hard to diagnosis if people aren't thinking about the disease. The most commonly identified problem is kidney disease, and early diagnosis and treatment is critical for successful treatment.
The Leptospira bacterium can survive well in the environment, particularly in moist conditions, and dogs are often exposed through wet environmental areas that have been contaminated with leptospires from the urine of infected wildlife. The strain that has predominated in the latest Michigan cases is Leptospira Icterohemorrhagiae, a type most often associated with rats.
Prevention of leptospirosis involves avoiding exposure to the bacterium as much as possible (largely through avoiding contact with wet areas where lepto cases have been identified) and vaccination. Vaccines are available for dogs and they can reduce the incidence and severity of disease caused by four different lepto types, including Icterohemorrhagiae. Vaccination should be considered in dogs in regions where lepto cases are identified and in dogs at increased risk of exposure based on lifestyle and travel.
There have been a few large outbreaks of dead birds around Ontario lately, with botulism being the main suspect. In one area alone, up to 6000 dead birds have washed up on Georgian Bay beaches. While dramatic, it's not a rare situation at this time of year, and typically relates to birds ingesting fish that died of botulism. When birds eat enough fish with enough botulinum toxin inside them, they can develop botulism themselves and die. This pattern can continue if dead birds are eaten by other animals.
In response to these events, I often get calls about risks to dogs and people. When thinking about it, it's important to consider how botulism occurs. There are two main forms of botulism:
- Toxicoinfectious botulism involves growth of the Clostridium botulinum bacterium in the intestinal tract, and as the bacterium multiplies it produces toxin which can be absorbed into the body through the intestinal wall. This type of botulism is rare in adults (both people and animals), since the mature intestinal bacterial population usually prevents C. botulinum from overgrowing. It's mainly a risk in young individuals. )This is why you're not supposed to give honey to babies, since C. botulinum spores that can be present in honey can pose a risk to them.)
- The other form of botulism in from ingestion of botulinum toxin that's already been produced. This is the most common form. When birds eat fish that have died of botulism, they ingest both the bacterium and its toxins, but it's the toxins that make them ill and ultimately lead to death. Dead birds will probably have some C. botulinum in their intestinal tracts, but the main concern is the botulinum toxin in the rest of their tissues.
Dogs (and cats) are quite resistant to botulinum toxin, and reports of botulism in these species are rare. It would take a pretty large amount of toxin to cause disease (at least compared to many other species) but it's not impossible. Casual contact with areas where birds have died is of basically no risk. Eating dead birds could pose some risk to the dog, depending on the amount eaten and how much toxin was present in the bodies. Ingestion of some C. botulinum bacteria in the birds is of limited concern.
So, walking in an area where birds have died is very low risk. People should ensure that their dogs don't have uncontrolled access to areas where birds have died, so that they can't eat lots of dead birds.
I also get questions about whether dogs that get exposed to beaches where birds have died pose any risk:
- Even if a dog ate a lot of dead birds and got botulism, a person could only be exposed to that toxin by eating the dog - an unlikely event. The dog could ingest some C. botulinum bacterium, but this also poses minimal risk since the bacterium is pretty widespread and people can be exposed to it from many different sources. Even if a dog had some C. botulinum in its intestinal tract, avoiding contact with feces will reduce the risk of exposure. Even if there was some ingestion of C. botulinum from the feces, there's little risk, especially to adults. Perhaps the main public health concern (which is still very low) would be exposure of infants to C. botulinum from dog feces or perhaps from a dog's contaminated haircoat.
Bottom line: Keeping dogs and cats away from dead birds is a good idea, for several reasons, including botulism exposure, but there's limited public health concern.
Image: Dead birds washed up on the shore of Georgian Bay, on the eastern side of Lake Huron (click for source)
Here’s a recent question I received:
"My problem is that the raccoon broke a window, came into my house, ate the cat food and then defecated on the kitchen floor. Since they went a day without food, the cats may have eaten the few bits of food that were left behind. How can I tell if they got the roundworm?"
It’s a reasonable question given the concerns about Baylisascaris procyonis, the raccoon roundworm. However, there’s basically no risk. While it is very likely that the raccoons were shedding roundworm eggs in their feces, those eggs are not immediately infective. Ingesting a "fresh" roundworm egg isn't a risk. Eggs have to sit around in the environment for at least 11 days (typically 14-28 days) before they become infective. Therefore, unless the feces are allowed to sit around in the house for a couple of weeks, roundworm infection isn’t a concern in such a case.
NDM-1 (New Delhi metalloproteinase 1) is a little bacterial gene that's attracted a lot of attention (and controversy, due to its name). NDM-1 can be picked up by certain types of bacteria, making them resistant to a whole lot of antibiotics. Some bacteria that carry NDM-1 are resistant to virtually every available antibiotic, which raises the spectre of the "untreatable infection."
Since it's discovery, NDM-1 has been found in multiple countries, often in people that were in India as tourists (or "medical tourists" who traveled to India for medical procedures they couldn't have done in their own countries), and in a few different types of bacteria. Recently, NDM-1 was found in an American upon his return from India, this time in Salmonella (Savard et al. 2011, Antimicrobial Agents and Chemotherapy).
The 61-year-old man was hospitalized in India in late December 2010 following a severe bleed in his brain. He was transferred back to the US on January 25, 2011. Upon arrival, he developed a fever and a multidrug-resistant bacterium, Klebsiella pneumoniae, was isolated from his breathing tube. This was concerning by itself, but later, Salmonella Senftenberg was isolated from the man's rectum. The strain was highly atimicrobial-resistant and was determined to carry the NDM-1 gene.
There have been complaints from people in India about the stigma associated with the "New Delhi" component of the name. In hindsight, many people wish it had been named differently because of this, but at least at the moment, it's undeniable that India is a (or the) hotbed of NDM-1. It's been found in various bacteria from water and seepage samples in New Delhi, but this is the first report in Salmonella. It's concerning because of the difficulty that would be encountered treating highly resistant Salmonella in infected people. Usually, antibiotics aren't needed when someone has salmonellosis, but when they are needed, it's important that they work. Highly drug resistant strains increase the chance of a bad outcome if ineffective antibiotics are used initially (before it's determined that the strain is resistant).
NDM-1 has not been reported in animals... yet. I assume it's inevitable that it will occur, since this gene appears quite able to move between bacterial species. If it increases in humans and in human-feces-contaminated sources like water, exposure of animals will certainly occur. If NDM-1 containing bacteria establish themselves in the intestinal tracts of healthy animals, it's going to be much harder to control.
Infectious diseases are continuous challenges for animal shelters. Unfortunately, outbreaks are not uncommon. Sometimes they're the result bad luck and the inherent risks involved in bringing together lots of animals of questionable health status from different sources. However, if you compound these risks with things like inadequate facilities, overcrowding, poor training of personnel, poor adherence to protocols, bad protocols, lack of awareness about infectious diseases and failure to get expert help early in any outbreak, the likelihood of "badness" increases.
A few shelter outbreaks are underway at the moment, and they highlight some of the infectious disease challenges posed by different diseases in animal shelters.
- The Oakville and Milton Humane Society (in Ontario) is closed because of a ringworm outbreak that's been going on since early September. Ringworm, while of limited health consequences, is an important shelter problem because it's common, highly transmissible, can be hard to control and can infect people. At last report, 22 cats were confirmed or suspected to have ringworm, along with at least four staff members. It's not clear who's coordinating the outbreak response, but hopefully they're getting good advice and they've read the comprehensive report from the Newmarket OSPCA ringworm debacle.
- 72 kittens were euthanized in the Miami-Dade County Animal Services because of "cat plague," which is a common name for feline panleukopenia. This viral disease is preventable by vaccination, but it's a serious concern in shelters were there are often lots of unvaccinated or inadequately-vaccinated cats and lots of susceptible kittens. In this shelter, all cats with clinical signs consistent with panleukopenia are being euthanized. Euthanasia is always a tough decision, but with a serious disease like this, it's a reasonable response. Outbreaks like this highlight the need for excellent infection control practices to reduce the risk of spread of pathogens like this once they make it into a shelter.
- Upper respiratory tract infections have resulted in suspension of adoptions at the Bergen County Animal Shelter in New Jersey. News reports are calling it a canine influenza outbreak, and canine flu is definitely on the list of possibilities, but it doesn't sound like it's been confirmed. Respiratory infections are a common cause of problems in animal shelters because some causes (e.g. canine parainfluenza virus, canine influenza virus) are quite transmissible. Canine flu poses extra challenges when it moves into a new area, since few if any dogs have antibodies against the virus and therefore it can spread rapidly. The report also mentions transmission by dogs not showing signs of disease. That's a problem with some infectious agents. For example, with canine flu, dogs tend to be able to shed the virus before they show signs of illness. Therefore, there's a period of a couple of days after infection but before disease where you can have a silent reservoir of infection. That's why quarantine of new admissions is critical, since it gives animals a few days to show signs of diseases they may be brewing at the time of admission. (Unfortunately, it's not easy to find space in which to quarantine an animal in an overcrowded shelter.)
A common denominator in all of these outbreaks is the potential that something could have been done differently to prevent the problem. It's possible (although unlikely) that everything that was done perfectly, however it's a rare outbreak where you can't find multiple areas for improvement. A key aspect of outbreak management is, once the crisis is over, performing an investigation of what really went wrong and why, and taking measures to reduce the chance of it happening again.
Image: Ringworm infection in a cat is not always readily apparent, but in some cases can cause obvious patches of hair loss.
A recent article in the Toronto Sun described one physician's approach to dealing with dig bites in kids. It contains some useful information, but also a couple of areas that probably require some clarification.
In the article, the physician lays out a few points regarding management of dog bites in kids:
The first thing a parent should do after such a bite is to stop the bleeding by applying pressure. Then, clean the area with warm water and soap. Dogs, like humans, have dirty mouths, so you want to wash and rinse well and even flush out the wound if it's deep.
- "The solution to pollution is dilution" is a old adage. Thorough cleaning is a critical step.
If the bite wound is small, it's usually not sutured, as this might increase the risk of infection. On the other hand, facial wounds and larger bites have to be well cleansed and irrigated, and may require stitches. The sooner this can be done the better.
For a child with a dog bite that has broken the skin, most pediatricians would recommend a seven-day course of an antibiotic, typically Augmentin (unless the child is allergic to penicillin).
- I'm not sure "most" doctors would start a child on antibiotics after any bite that has broken the skin - at least I hope not. Typical recommendations for bites include that antibiotics should be considered with moderate to severe injuries, puncture wounds, people with compromised immune systems and bites over specific areas like joints or the face. Antibiotics for minor soft tissue injuries in otherwise healthy individuals are not typically recommended, although there is some controversy.
Rabies is usually not a risk in dogs that are family pets and live in homes. If the dog is not known or their rabies status is unclear and you can't locate the pet, check with your pediatrician about rabies prophylaxis.
- True. Rabies from pet dogs is very rare in North America. However, if you get it, you almost certainly die, so we take precautions even in low risk situations. So, a little more discussion of this point is important.
- Every dog bite must be approached as a potential rabies exposure. Key points for this are identifying the dog and ensuring it's quarantined for 10 days. After 10 days, if it's healthy, it couldn't have transmitted rabies with the bite. Related to this, any dog bite should be reported to local Public Health personnel. They will ensure that quarantine is imposed if the dog is known, and facilitate rabies post-exposure prophylaxis in the rare situations that it is needed. In Ontario, physicians are bound by law to report bites to Public Health.
Dog bites are unfortunately very common. Usually they are minor and heal without much trouble, but serious or fatal injuries can occur and infections are a potential problem. Knowing what to do in response to a dog bite is important to reduce the risk of a range of complications.
The CDC's annual animal rabies surveillance report has been published in a recent edition of the Journal of the American Veterinary Medical Association (Blanton et al 2011). It's the regular synopsis of the state of rabies in domestic animals and wildlife in the country. It contains some interesting information but few surprises. Among the highlights:
- Rabies was identified in 6154 animals in 48 US states, plus Puerto Rico. The true number of animals that died of rabies in the year would have been much higher, since not all animals (particularly wildlife) that die of rabies get tested.
- 92% of positive animals were wildlife, including raccoons (37% of cases), skunks (24%), bats (23%) and foxes (7%).
- Cats were the most commonly affected domestic animal, accounting for 4.9% of cases (303 cats), followed by cattle (1.1%), dogs (1.1%) and horses (0.6%).
- Different rabies virus variants predominated in different regions. For example, raccoon rabies virus was most common on the east coast. Different skunk rabies variants predominated in the south-central and north-central regions, along with California and Nevada. A couple of pockets of fox rabies were present in the southwest, along with one in Alaska. Mongoose variant was present in Puerto Rico. Bat variants were spread out across the country.
- Most rabid cats were from states where raccoon rabies is endemic. About 1/3 of infected cats were from Pennsylvania and New York. Texas was the leader in dog rabies, followed by Puerto Rico and Virginia.
- Two cases of rabies in humans were identified, compared to 4 in 2009. One was a migrant worker infected by a vampire bite while in Mexico. The other was a man from Wisconsin who was infected with a bat rabies strain. Both died.
Canadian and Mexican data are also reported:
- 123 cases of rabies were identified in Canada, 93% of which were wildlife. 7 (5.7%) were dogs or cats. No rabid raccoons were identified, continuing a trend that has been observed since 2009. Bats and skunks were the wildlife leaders. No people were infected.
- 357 cases were reported in Mexico. 83% were cattle, 20 were dogs. Four human cases were identified.
While rabies does not exert anywhere near the impact on people in North America compared to many other regions (where tens of thousands of people die from the disease every year), it continues to take its toll on wildlife and, to a lesser degree, domestic animals. It's also a preventable disease that can be controlled with vaccination, and human cases can effectively be eliminate by proper post-exposure treatment. Continued efforts are needed to reduce rabies in wild and domestic animal populations, for both the protection of those populations and protection of the people who may come in contact with them.
While it's not really an occasion to celebrate, September 28 was World Rabies Day. Rabies has been a problem for millennia, and it's not going away any time soon. This viral disease, which is almost invariably fatal, kills 50 000 - 70 000 people per year. Some countries have astounding rates of rabies cases, such as India where ~20 000 people die of the disease every year. Internationally, most human rabies infections are caused by dogs, but wildlife are the main source in some regions (such as Canada and the US) . Basically all rabies infections are preventable with proper access to good medical care and rabies post-exposure prophylaxis, but sadly the thousands of people who die do not receive treatment.
Is rabies controllable? Yes. With measures to reduce rabies in wild and stray animals, pet vaccination, public education measures, good access to medical care, adequate rabies vaccine supplies and adequately trained healthcare personnel, the incidence of rabies can be dramatically decreased. However, these measures require time, money, effort and political will, and those are limitations in some areas.
Can rabies be eradicated? That's a tough question. Eradicating a disease that can be found in many wild animal species internationally is extremely difficult. It's hard to envision complete eradication of this virus, as was done for smallpox (a human-only disease) and rinderpest (a cattle-only disease). Both those diseases had the advantage of only being found in one species, making control and eradication much more feasible. However, while we might not be able to eradicate rabies, it's certain that tens of thousands of lives could be saved every year with good rabies control programs.
More information about rabies can be found in on the Worms & Germs Resource page.
An outbreak of canine influenza is occurring in San Antonio, TX, as this virus continues its strange and unpredictable movement through the North American dog population. In an article published on a local San Antonio news website, Dr. Michele Wright, a San Antonio veterinarian, reports 20 confirmed and 70 suspected cases over the past month. It's not clear whether these are all from her clinic, nor is there any information about possible sources of the virus or the severity of disease. Dr. Wright also states that the virus has been identified in Austin and Dallas.
It's not particularly surprising that canine flu has been found in Texas. It's now been identified in at least 38 US states, as well as one Canadian province. An outbreak is not particularly surprising either in this case, because when a virus reaches a new area, it can easily cause widespread disease since it encounters a population of animals that don't have any pre-existing immunity (i.e. antibodies) against it.
What's strange about canine flu is how it has spread across North America. When it was first identified in Florida greyhounds in 2004, it seemed like it was going to spread widely across the dog population. It spread quickly at greyhound tracks and in clusters in Florida and in other states, but it's subsequent spread across the continent was quite patchy - it caused only localized outbreaks in different states, instead of the catastrophic continent-wide epidemic that was anticipated. Whether this relates to the amount and type of direct contact between dogs (e.g. dogs are only infectious for a short period of time and an infected dog has to meet a susceptible dog during that time to continue transmission of the virus, otherwise it dies out), specific aspects of the virus in dogs (e.g. how long it is shed) or lack of recognition of disease in some areas (e.g. mild disease that doesn't get diagnosed) is unclear.
We've been looking for canine flu in Ontario for a few years now, with no "success" (that is, we haven't found it yet).
Are we flu-free at the moment? Probably not. I suspect it's lurking out there, but it's possible that it really hasn't made it to Ontario - yet.
If it's not here now, will it make it here eventually? Almost certainly. It's taking longer than I expected but all it takes is one infected dog entering the country. With the amount of cross-border dog movement, it's probably inevitable.
What about vaccination for canine flu? It comes down to risk of exposure and risk aversion. If flu is in the area, vaccination is a good idea. If flu is in adjacent areas, it's also a good idea. If flu isn't recognized in the area, it's a matter of how much risk people are willing to take and thinking about higher risk situations, as described below.
What about vaccination in Ontario, or other places where the virus doesn't seem to be present? It's hard to say when to recommend canine flu vaccination. Certainly, vaccination of dogs traveling to areas where canine flu is or has been present is a good idea. Vaccination of dogs that engage in high risk activities such as going to shows or kennels is also prudent, since these are the places where we may see the firsts outbreaks if/when canine flu makes it here. Vaccination of low-risk dogs in the province is probably not necessary at the moment (unless people are very risk averse and don't want to take any chances).
Why vaccinate? It's just "the flu"... This is an attitude that the human public health field battles all the time. Most people who get human influenza (humans can't get the dog version of the virus) feel crappy for a few days and get over it. The perception that it's only and always a mild disease keeps some people from getting vaccinated. However, thousands of people die from flu complications, particularly the very young and elderly individuals. Vaccinating everyone helps reduce the chance that these high-risk people will get sick. Also, while rare, serious (including fatal) infections can occur in otherwise healthy people. In dogs, there's probably actually more indication to vaccinate if there is a realistic risk of exposure. Canine flu can cause classical flu-like disease, akin to the typical human case. However, severe (often fatal) pneumonia can also occur in otherwise healthy dogs. High rates of severe disease were reported initially when canine flu was first identified. It seems like severe disease rates have dropped, but it's still a concern. I wouldn't be surprised if severe disease is more common in dogs with canine flu than in people with human flu.
Whether or not to vaccinate is a discussion dog owners should have with their veterinarian, considering the risk of exposure, risk of severe illness and risk aversion. At the same time, people in areas where flu has not been identified need to be on the lookout for it, to ensure that it gets diagnosed promptly if it emerges, and that information gets communicated to veterinarians and the dog-owning public so that appropriate responses can be made.
The latest update on equine infecious neurological diseases in Ontario (Eastern equine encephalitis (EEE), West Nile virus (WNV), rabies and neuropathic equine herpevirus type 1 (EHV-1)) is available from the Ontario Ministry of Agriculture, Food and Rural Affairs.
There aren't a lot of surprises, and it's good to see the numbers of cases have remained relatively low. Most notably, there have been three EEE and five WNV cases confirmed, from different regions of the province. This shows that these diseases are still occurring in Ontario horses, albeit at a very low rate.
You always have to consider the limitations of surveillance data like this. To make the list, a horse has to get infected, get sick enough for someone to notice, a veterinarian has to be called and proper samples have to be taken for diagnostic testing. There's certainly no guarantee that this happens in all instances, and it's reasonable to assume that a few more cases of these diseases have occurred in Ontario this year.
In Ontario, August and September tend to be the months of highest activity for EEE and WNV, and as we move into cooler weather (and decreased mosquito activity) the risk of EEE and WNV will start to plummet. I wouldn't be surprised if the numbers increase slightly by the time the final tally is made, but there are no indications that we have major disease activity at the moment.
Surveillance data such as this, including total numbers of cases in the province and an indication of areas where case occur, are important for horse owners and veterinarians to consider when determining their vaccination programs.
A case report highlighted by TheHorse.com and presented at the ASM/ESCMID MRSA conference in Washington DC last week described a horse-associated methicillin-resistant Staphylococcus aureus (MRSA) infection in Dutch girl.
The girl, a 16-year-old with a severe neuromuscular disease who was wheelchair-bound and on a ventilator, developed an infection following an insect bite. When the infection didn't respond to initial treatment, a sample was taken for culture and MRSA was identified. The girl didn't have any known risk factors for MRSA infection but had had close contact with a foal. The Friesian foal had been at a veterinary hospital prior to the girl's infection. It had a wound infection that was successfully treated with antibiotics, but no culture was taken at the time. The foal was considered a possible source of the MRSA, particularly since the strain that was recovered was ST398, which is widely found in livestock and which is regularly seen in horses in the Netherlands. After the girl's infection was identified, the foal was tested and was also found to be carrying MRSA. The girl's infection was successfully treated and the foal eliminated MRSA carriage without treatment (which is expected in horses because long-term carriage of MRSA seems to be rare to non-existent in this species).
The source of the infection could not be definitively proven, but given the fact that the horse was at a facility that regularly sees MRSA cases, that the strain involved is typically associated with livestock, and that the girl had no other livestock contact, it's a reasonable to assume it came from the foal.
We've known for a few years that MRSA is an issue in horses, and that it can be passed between horses and people - in both directions. Equine veterinarians and horse owners have abnormally high MRSA carriage rates. MRSA carriers are people who have MRSA living in or on them (most often in the nose) without any signs of infection. Most carriers never have a problem, but disease can develop in some situations. The incidence of human MRSA infections transmitted from horses is low, although it's almost certain that many horse-associated MRSA infections are not reported because the link with horses isn't made or people don't mention the horse contact. TheHorse.com article is incorrect in stating that this is only the third case of horse-to-human MRSA infection, since we've already published two such reports, one of which included multiple cases. Regardless, it's an uncommon problem but it is probably also under-recognized. Horse owners shouldn't panic about MRSA, but they should realize that MRSA is circulating in the horse population and that by nature of their frequent and close contact with horses, they are at higher risk for MRSA carriage, and likely also infection.
More information about MRSA in horses can be found on the Worms & Germs Resources - Horses page.
The latest edition of Emerging Infectious Diseases (Berger et al 2011) describes a case of Corynebacterium ulcerans infection in a women that was likely acquired from her cat.
Corynebacterium ulcerans is a bacterium that's related to C. diphtheriae, the cause of diphtheria. Some strains of C. ulcerans can produce toxins that cause diphtheria-like disease, and with the success of diphtheria vaccination, C. ulcerans is now the leading cause of diphtheria-like disease in people in some regions. Typically, C. ulcerans infections are associated with ingestion of contaminated milk or dairy products, but reports of infections acquired from dogs and cats appear to be on the rise. As is often the case, whether this is because it's becoming more common or that people are simply looking more is unclear.
In this report, a woman from Germany developed diphtheria-like disease, including a sore throat, ear ache, hoarseness and nasal obstruction. A swab was taken from her nose and throat, and toxigenic C. ulcerans was isolated. She didn't report any livestock contact and had not traveled abroad, so other possible sources of infection were considered, particularly other types of animal contact. She had a cat, so nose and throat swabs were collected from her pet, and the same strain of C. ulcerans was isolated.
With this type of investigation, you can't prove that the cat gave the bug to the owner. Since the cat was healthy and tested after the owner was sick, you can't say for sure whether the cat was the original source or if it was infected by the owner. However, with a bug like C. ulcerans that has been associated with pets before and that can be carried by healthy cats, the conclusion that it came from the cat is reasonable. The cat was treated with antibiotics and C. ulcerans was not detected after treatment.
This is an interesting report. It's always good to see people thinking about the relationship between human and animal disease, but at the same time, it's important to put this into context. Yes, C. ulcerans is a potential zoonotic concern, but it's rare. Anytime you see a case report involving a single person in the medical literature, you know it's either something new or very rare. In this case, it's the latter, since we know from previous reports that this bug can cause human infection and be transmitted from animals. Rare doesn't mean never, and you can't dismiss it, but C. ulcerans is just one of many bacteria that can be found in cats and transmitted to people. It's part of the inherent risk of infection that comes with cat ownership. This relatively low risk is hopefully outweighed by the benefits of cat ownership, and the cost-benefit can be maximized by basic infection control and hygiene practices. This report also shows how it's important for physicians to query pet ownership when dealing with infectious diseases in their patients, something that still needs lots of improvement.
Overall, there’s good information in the document with an emphasis on routine infection control as the key measure to reduce the impact of MRSP and MRSA. I’d like to see more emphasis on developing an overall infection control program, but the emphasis on basic principles such as hygiene is good.
Like any guideline document, there will be some disagreements in recommendations. I agree with the majority of what's written, although there are some recommendations that I wouldn’t make, and some additional areas that I’d address. That’s not surprising since most of the recommendations are based on opinion rather than evidence because we don’t have solid evidence for most areas, and there isn’t necessarily a single "right" answer to many questions at this point.
Typically, guidelines assess and report the level of evidence on which recommendations are based, but that’s not done here. Letting people know the evidence (or here, the relative lack of evidence) is a useful part of guidelines. How the recommendations are worded can also play a role. Here, they perhaps overstate the strength of evidence through use of wording such as saying something "will" have an impact, when we really should say it "might." In the absence of evidence, good common sense measures can be recommended and implemented, however we need to remember that we have major limitations in our knowledge. We need to figure out which infection control practices are effective.
I have a major problem with one recommendation: "Colonised animals should be treated with a chlorhexidine shampoo and intranasal fusidic acid or mupirocin once daily." There is simple no evidence supporting the use of active measures to eliminate MRSA and MRSP.
- For MRSA, there is reasonably good evidence that dogs and cats eliminate it on their own in a reasonably short period of time.
- For MRSP, we simply don’t know how long they can be carriers. I suspect that long-term carriage can happen in some animals, so decolonization might be attractive, but we don’t know what to do yet.
- There is absolutely no evidence that intranasal antibiotics are effective in dogs and cats. I have serious doubts that someone can adequately administer a topical antibiotic to the nasal passages of a dog, and particularly a cat.
- If this recommendation is adopted and widely used in the UK, I suspect the country will be an international leader in fusidic acid- and mupirocin-resistant bacteria.
Overall, there are some good recommendations in the guidelines, including the general infection control sections. We need to improve our baseline level of infection control and hygiene to reduce the impact of MRSA, MRSP and a variety of other concerning microorganisms. At the same time, we need to acknowledge our limited knowledge in a lot of areas and the fact that we are really working based on common sense and extrapolation from human medicine, with little direct evidence from veterinary medicine. Much more research is necessary, a major limitation of which is the limited priority given to companion animal infection control by research funding agencies. This has to change to help control the impact of bugs like MRSA and MRSP on both animals and people.
A paper in the Journal of Neurooncology (Redelman-Sidi et al, 2011) describes "kitten-transmitted Bordetella bronchiseptica infection" in a cancer patient. The patient in question had a brain tumour that was surgically removed. The 56-year-old man was then started on chemotherapy, which in addition to killing cancer cells can also cause significant impairment of the immune system, which puts chemotherapy patients at high risk for infections of many kinds. This particular patient developed a persistent cough during treatment and was eventually diagnosed with B. bronchiseptica infection. This bacterium is one of the causes of kennel cough in dogs, and can cause respiratory infections in other species, including cats.
The man had acquired a kitten three weeks before he developed the cough. The kitten had (at some undefined time) conjuncitivitis and signs of respiratory disease. Unfortunately, as is too often the case in reports of supposed pet-associated disease in the medical literature, the kitten was not actually tested. Bordetella bronchiseptica is classically an animal-associated organism, the kitten was newly acquired and it had respiratory disease. These factors strongly suggests the kitten was the source. However, without testing of the kitten and investigation of other potential sources of infection, it's hard to be as definitive as the title suggests. The suspicion of the kitten being the origin is reasonable nonetheless.
Some statements from this report are contrary to my typical recommendations for pets and immunocompromised individuals.
Getting a young animal
- Kittens and puppies are entertaining, but they are also higher-risk animals compared to adult dogs and cats. They are more likely to harbour a variety of infectious agents. They are also more likely to bite or scratch through playful or rambunctious behaviour, and it's harder to properly assess their temperament. If an immunocompromised person wants to get a new pet, getting an mature animal is ideal.
Source of the kitten
- The paper unfortunately doesn't mention from where the kitten was obtained and whether there was a respiratory disease problem in other animals at the source. Animals in shelters, humane societies and pet stores are more likely to carry various infectious diseases because they are densely populated facilities, often have infection control challenges, house many high-risk animals and are stressful environments. Getting new animals from these places is not ideal for a high-risk person.
- The kitten had signs of respiratory disease and was seen be a veterinarian. It doesn't appear that any testing was done and the kitten was just treated with antibiotics. That's pretty common, but in a situation where there is a high-risk person in the house, it's wise to be more aggressive with diagnostic testing to determine whether there may be any concerns for the person.
A pet can be a wonderful thing for a person living cancer, by providing social and emotional support, along with other benefits. Pet ownership always carries some risk of zoonotic infections, and the risk is higher in people with compromised immune systems. Rarely, if ever, is pet ownership inappropriate for a cancer patient, although certain pets and certain situations might be, and high-risk individuals need to think about possible risks and measures to reduce those risks.
People with cancer or other problems affecting their immune system should ensure that their physician knows that they own pets. Veterinarians need to play a role as a member of the overall healthcare team too. Optimizing pet health can help reduce the risk of human infection. Prompt and proper diagnostic testing can identify potential issues. Proper counseling can reduce risky situations from inappropriate pets, inappropriate contacts and other factors that might make exposure to a nasty infection from a pet more likely.
Rabies is pretty rare in horses, but there have been a few reports this summer. Though rare, rabies is still a major concern because it's invariably fatal in horses, and almost always fatal in people.
Rabies was recently diagnosed in a horse in Eddy County, New Mexico. It started showing undefined signs of rabies and was euthanized two days later. Several people who worked with the horse are undergoing post-exposure treatment.
While rabies can potentially be spread from horses to people, I'm not aware of any confirmed cases of such transmission. Since rabies usually kills people, even a plausible risk is cause for concern. Additionally, and perhaps more importantly, rabid horses can be very dangerous, and multiple people have been killed by aggressive rabid horses.
Rabies should be a core component of a horse's vaccination program in any part of the world where rabies is present in the wildlife population. Unfortunately, that's not always understood. One area resident stated she'd never heard of rabies in horses, and while she has her dogs and cats vaccinated, she hasn't vaccinated her livestock. No vaccine is 100% preventative, but rabies vaccination is a cheap and very effective way to reduce the risk of this fatal disease significantly.
A recent case of canine rabies in France showed yet again the risks posed by illegal importation of animals. This case is somewhat unusual since it seems to involve ignorance of the rules and lax enforcement, compared to rampant animal smuggling, but the end result was the same.
The animal in question was a puppy that was brought to France by a family that had been vacationing in Morocco. They found the puppy on July 11 and returned to France on July 31. European Union regulations require that imported dogs be vaccinated against rabies and microchipped. Neither was done to this puppy, and it was in fact too young to vaccinate against rabies according to standard protocols. The family traveled back to France by ferry and car, and either met no customs officials or at least no officials who asked any questions about the puppy.
They day after they returned to France, the puppy started to exhibit behavioural changes and progressive sleepiness, with subsequent development of aggression. Five days later, it was taken to a veterinarian and it died the next day. Rabies was confirmed a few days later, and testing of the virus strain indicated that it was of the Africa-1 lineage and closely related to strains previously isolated in Morocco.
An investigation into possible rabies exposure ensued. Typically, it is assumed that animals can be infectious for up to 10 days prior to showing signs of rabies. Often, this is extended by several days for added confidence and because it's not always possible to determine exactly when the earliest, mildest signs might have developed. In this case, they considered the period that rabies could have been transmitted to be from July 18 until the puppy's death.
Multiple people had close contact with the puppy. Three family members had been bitten, a clear indication for post-exposure treatment. One other person (a friend of the family, it appears) was also bitten and received treatment. Another person reported being licked on non-intact skin (i.e. an area of skin with a cut, abrasion or other break in the normal barrier) and was also treated. The attending veterinarian, who had been previously vaccinated, received two booster shots.
This isn't the first time that rabies has made its way from Morocco to France, and it's concerning that it was so easy for it to happen. Nine rabid dogs have been illegally imported to France from Morocco since 2001. In 2008, one such dog subsequently transmitted rabies to several other dogs, resulting in France losing its rabies-free status until February 2010. It's not surprising that no questions were asked of the family traveling from Spain to France because of the open nature of borders between EU countries, but the ability to enter Spain from Morocco with no flags being raised is a concern. Hopefully there's an investigation into how this puppy was able to get into Europe so easily and how to reduce the chances of this happening again.
Bites from the brown recluse spider (see photo left) can be pretty nasty, and produce tissue damage similar to a typical MRSA skin and soft tissue infection. Despite the epidemic of MRSA that's ongoing in many regions, particularly the US, MRSA infections are still sometimes misdiagnosed as spider bites.
To a degree, I can see why this might happen in areas where the brown recluse spider lives (i.e. the yellow area on the map at right) and where these spider bites certainly occur. Even in these regions though, taking a culture to rule out MRSA is about as simple as it gets. Sadly, erroneous spider bite diagnoses also happen in areas where the brown recluse spider doesn't even exist.
Does this relate to animals? Not really. Unlike people, animals rarely develop the type of skin infection that mimics a spider bite, so misdiagnosis as a spider bite is unlikely (although it does sometime occur). Failure to properly consider MRSA and test for it is still a problem in animals.
Source of images: http://en.wikipedia.org/wiki/Brown_recluse_spider
China has a huge canine rabies problem, with thousands of human rabies deaths each year. There are several reasons for this, including large feral dog populations, inadequate vaccination of pet dogs, differences in approach and access to veterinary care for pets, inadequate education regarding dog bite prevention, and presumably inadequate education of people and/or healthcare personnel regarding when and how to seek proper post-exposure treatment.
Periodically, the knee-jerk reaction of dog culling rears its head in China, despite the ineffectiveness of culling alone as a rabies control tool.
Recently, authorities in Guangdong province have banned ownership of dogs (in most situations) and given residents until August 26 to get rid of their pets. Dogs remaining at that time will be put down, except for dogs that are used to protect property worth ~ $750 000 (or more). Those dogs must be vaccinated and "kept locked up." (Why the same things (i.e. vaccination and confinement) can't be done with any other pet dog is unclear, since being owned by a rich person doesn't make a dog less susceptible to rabies.)
An expert from the Chinese Center for Disease Control summed up the issue nicely: "This [ban] is not scientific, not humane, and it will not last long. In short term, maybe it could be effective, but after that, people still want to keep dogs."
Culls don't work well. A cull can decrease the population of concern for a time, but it's extremely unlikely that it would reduce the population enough to have any longterm effect. Dogs can reproduce quickly and replace the culled animals in a short period of time.
What would make more sense?
- Widespread vaccination of pet dogs, to reduce the risk of exposure of people from pets that get infected from feral dogs.
- Widespread vaccination of feral dogs, to reduce exposure of people and pet dogs. Achieving high vaccination rates (>70%) in the feral population is a critical control measure, but can be very challenging.
- Education of people about dog bite prevention.
- Education of people about dog bite care, particularly ensuring that they seek post-exposure treatment if bitten by a feral dog or a dog of unknown rabies status that can't be quarantined for 10 days to ensure it's not rabid.
- Education of healthcare personnel so that everyone who needs post-exposure treatment gets it (and gets it done right).
- Education of public health personnel to ensure that the two points above get done right.
- Ensuring adequate supply of good quality rabies vaccine and antibody for post-exposure treatment.
Yes, these measures require more work than a cull, and to some degree they also require a culture shift in the approach to keeping pets, but if China really wants to start preventing the thousands of rabies deaths that occur annually, that's what needs to be done.
Close to a dozen dogs in the Big Bay area of Michigan's upper peninsula have been diagnosed with blastomycosis, an uncommon but regionally important disease. Blastomycosis is caused by a fungus, Blastomyces dermatitidis. It's a dimorphic fungus, meaning it exists in 2 forms:
- Normally, it lives in the environment in the mold form. This is the infectious form to which dogs (and people) can be exposed via inhalation, ingestion or contamination of wounds.
- The other form is the yeast form. This develops from the mold form once it gets into the body, and this is what causes disease.
Dogs that are infected with blasto are of minimal risk to others since they are carrying the yeast form, and the yeast form is not transmissible under normal conditions. There is only a risk of infection in rare situations, such as a bite from a dog that has the yeast form in its mouth, or if someone sticks themselves with a needle that was used to sample an infected site. The main issue with finding blasto in a dog is that it is an indication that the fungus is present in the environment in the area where the dog has been in the past few months. That means people who went to those areas may have also been exposed.
Knowing where blasto is present is important for diagnosing disease in people and animals. Blasto is also a great example of a disease when getting a travel history can be critical for diagnosis. In some regions, blasto is most common where people tend to vacation or have cottages. If a veterinarian doesn't know that a dog has visited a high-risk area, blasto may not be considered. Not asking about travel history (or not getting a clear answer) can significantly impact the ability to diagnose this disease, and early diagnosis and treatment are critical for getting a good response.
If you live in an area where blasto is present, avoiding it can be tough. Staying away from areas that have been associated with the fungus can help, but defining this is difficult because of poor reporting and the long incubation period. Staying away from soil is pretty tough to do as a routine measure, so people living in endemic areas have to be aware of the disease and ensure that proper veterinary care is provided if there are early signs of infection (e.g. respiratory disease, skin lesion, unexplained weight loss). People who travel to areas where blasto is present should make sure their veterinarian knows about the potential for blasto exposure in any animals that may travel with them.
Adding a new twist to the already very concerning situation in Australia, Hendra virus infection has now also been identified in a dog. It's been a bad year for Hendra virus in Australia, with larger numbers of cases of this highly fatal disease in horses in a geographic range that seems to be expanding. Spread by flying foxes (fruit bats), Hendra virus predominantly infects horses, but can be transmitted to people working with infectedhorses.
The Australian Animal Health Laboratory in Geelong has now announced diagnosis of Hendra virus infection in a dog. The dog is from a quarantined farm in Queensland where the virus has been identified in a horse. The dog was healthy and was tested as part of a standard policy to test dogs and cats on infected farms. It's great to see this approach being used, since it helps identify other potential sources proactively - something that is often overlooked in outbreak investigations that focus only on the main species that are already known to be involved.
In this case, the dog had antibodies against the virus in its blood. That means that it was exposed to the virus and mounted an immune response. It doesn't indicate whether it was exposed recently or in the past. Two tests for the virus itself were negative, suggesting that the dog's immune system eliminated the virus (or that the virus isn't really capable of surviving for long in a dog). This is a good news/bad news scenario.
- Dogs can be infected. It increases the range of known susceptible species.
- If dogs can be infected and shed live virus, then they could be a source of infection for other individuals, including people.
- The dog wasn't sick. This might sound like strange "bad news," but healthy carriers of infectious diseases are harder to spot and control than ones that are sick.
- The dog wasn't shedding the virus. That's critical since if dogs can be infected but not infectious (i.e. if they can carry the virus but not transmit it), then they are of limited concern.
- They have been testing farm dogs and cats as a routine measure, and this was the first positive. Infection of pets therefore must be relatively uncommon even on farms where the virus is active.
- The dog wasn't sick. While it's only one case and doesn't guarantee dogs won't be affected clinically, this might suggest that dogs just occasionally get exposed with no disease. Since it's highly fatal in other species, that's a good thing.
What should be done based on this?
- Probably not much more than should have been done before this finding, but it's a good reminder about the potential involvement of other species.
- Dogs and cats should be kept away from fruit bat roosting sites.
- Dogs and cats should be kept away from infected horses.
- If a farm is quarantined because of Hendra virus, dogs and cats should be tested and quarantined. Quarantining the animal while testing is underway helps reduce the risk of an infectious dog or cat (should that occur) transmiting the virus to people on the farm, or wandering away and exposing other people or animals.
- Animals of any type in areas where Hendra virus is active that get sick with signs that could possibly be consistent with Hendra virus infection should be tested.
This should also be taken as yet another reminder that infectious diseases are unpredictable. Considering the potential involvement of different species in a proactive manner as was done here is critical.
Image: Bay Horse and White Dog by George Stubbs (1724-1806)
This Worms & Germs blog entry was originally posted on equIDblog on 26-Jul-11.
A 73-year-old New Jersey woman has died of rabies after being bitten by an infected dog. The woman was visiting Haiti in April when she was bitten, and she developed signs of neurological disease in late June. Family members and healthcare workers are being assessed to determine whether they may have been exposed to rabies during care of the woman. If so, post-exposure treatment would be started.
Rabies is a devastating but almost 100% preventable disease. While rare in most developed countries, canine rabies is a huge problem internationally and kills tens of thousands of people every year. The main reason it kills so many people is because of inadequate access to proper post-exposure treatment or failure to seek medical care. Timely access to post-exposure care can virtually guarantee that a person won't get rabies.
Why this woman didn't get post-exposure prophylaxis (I'm making the assumption that she didn't) isn't reported, and it could be because of patient or healthcare factors such as:
- Assuming a minor bite isn't a big deal.
- Not thinking about the potential for rabies.
- No access to adequate heatlhcare.
- The physician not thinking about rabies.
- Inadequate or no supply of rabies vaccine (for post-exposure treatment).
All of these problems can occur. Education of the public and medical personnel, as well as ensuring adequate access to rabies vaccine, are critical to prevention.
More information about rabies can be found in the Worms & Germs Resources page.
As Australia faces a particularly bad year for Hendra virus, with possible expansion of the range of this serious disease, there have been calls for a mass cull of flying foxes (fruit bats). These bats are the reservoir of the virus but also a protected species. The virus lives in the bats and is spread mainly through their urine. Horses that are exposed to bat urine or feces (e.g. grazing under a tree where bats are roosting) can become infected and then serve as a source of human infection. Being a highly fatal disease for which there is no available vaccine, looking at ways to reduce exposure to the virus is critical. When you have a wildlife-associated disease, questions about trying to eliminate the wildlife source often arise. Any discussion of culling wildlife leads to intense debate, and this situation is no different. Some people support culling bats in areas around people and horses, while others are opposed on various grounds, including a lack of evidence that it will be effective.
Can fruit bat numbers really be decreased? A lot of bats would have to be killed to have a significant impact on the population. Bats can reproduce quickly and migrate readily, therefore a single cull may have only a limited and short-term effect. A good understanding of the dynamics of the bat population is required to determine how many would need to be killed in a given area to have any significant impact. As Biosecurity Queensland's chief veterinarian RIck Symons stated "Culling is against government policy. I believe in terms of biosecurity it's counterproductive, because it does stress flying foxes and they're more likely to excrete (the virus). It could be filled by another bat colony the next day and if you're moving them on, you're moving it on to somebody else and it's somebody else's problem, so that is not the solution."
Will a cull actually achieve anything? Even if effective at reducing bat numbers (probably just in the short term), culls don't necessarily have an impact on disease rates. All bats would not be eliminated, and it's unclear whether there is a critical mass of bats that is required to transmit infection or whether a small number of bats distributed across the same region would be as likely to result in infections. Small or temporary decreases in bat numbers may have no effect.
What unintended consequences might occur if a cull is effective at reducing bat numbers? Removing an animal from any ecosystem has an effect, and it's important to be confident that that effect isn't accompanied by problems of its own. I don't know enough about fruit bat ecology to say much here, but if this species is greatly reduced, are there other species that will come and occupy that ecological niche, and might they be associated with problems of their own? Careful scientific study can help to figure this out in theory, but you can never be certain.
Are other control measures, such as removing roosting sites from pastures and other bat avoidance measures, being adequately used? Culls should only be considered when other measures have failed, but it can be difficult to ensure or enforce compliance with these other measures. Certainly, people in endemic areas should remove trees in which bats roost from pastures. However, not all Hendra cases are associated with identifiable roosting sites. For example, one affected Queensland farm does not have any fruit bats residing on the property, but it lies along a common flight path for the bats.
It's easy to talk about avoiding a cull when you're not in the heart of the Hendra epidemic, and I understand the reasoning behind the calls for a cull. Hendra is a devastating disease that's a threat to both horse and human health, and it's unpredictable - and that's scarey for a lot of folks. People that have been exposed face an incredibly stressful period while they wait and see if they've been infected with a virus that kills in ~50% of cases. A vaccine is probably still a couple of years away, leaving a period of continued risk and stress. With such a serious disease, considering culling is reasonable. However, it can't be a knee-jerk reaction to public outcry. It needs to be based on sound science to ensure that if it's used, it will be effective. The impact on this protected species also can't be ignored.
This Worms & Germs blog entry was originally posted on equIDblog on 19-Jul-11.
A Chapel Hill, North Carolina woman is suing Orange County in response to quarantine of her dog because of possible rabies exposure. This lawsuit highlights some of the inconsistencies in application of current rules, along with some misunderstandings.
In February, her dog Russell was barking at something under her deck, and that something ended up being a raccoon with rabies. There's no evidence of a fight or contact, but it can't be ruled out. Because of this, the dog was considered potentially exposed. Russell was overdue for his rabies booster, so a strict six-month quarantine was required, and the county required that this be done at an approved facility, not in the home. (The alternative option was euthanasia.)
- The lawsuit is based on the inconsistent application of the rules by various counties. The owner is seeking permission to quarantine the dog at home. This is allowed in many regions, provided there is confidence that the owner is responsible enough to properly quarantine the animal.
- It's a reasonable argument that's based on subjective and variable application of rabies guidelines. Certainly, formal quarantine in a facility offers more containment. The question is when household quarantine is appropriate, in terms of the animal's risk of exposure and the ability of the household to properly quarantine the animal.
Some other highlights:
Russell was overdue for his rabies vaccine by 46 days.
- Dogs don't immediately go from protected to unprotected. Certainly, we want animals to be up-to-date on their vaccines, but some thought needs to go into dealing with potentially exposed overdue animals. The NASPHV Rabies Compendium states "Animals overdue for a booster vaccination need to be evaluated on a case-by-case basis (e.g. severity of exposure, time elapsed since last vaccination, number of prior vaccinations, current health status, local rabies epidemiology)."
- Knowing the age of the dog and the number of previous vaccines would help, but the news article reports vaccinations (plural), suggesting that he's been vaccinated more than once in the past. In a dog with a relatively low index of exposure that was only overdue by 46 days, it would seem reasonable to consider it protected and treat it as vaccinated (although it's hard to say this definitively based on a news report that doesn't give the whole story). It's a critical point because considering the dog up-to-date would only result in a 45 day observation period as opposed to a strict six-month quarantine.
The owner's veterinarian stated that research shows that an animal that is vaccinated regularly is protected for many years, if not a lifetime.
- Yes and no. Vaccination is quite effective and in most animals probably confers long-lasting protection. However, I'm not aware of research that really shows this. This isn't a disease where we have good research data about duration of effect of vaccination. I suspect that most dogs that have been regularly vaccinated are well protected. Most does not equal all, and with a disease like rabies, you have to be quite sure.
A rabies antibody titre was measured. This is a blood test indicating the level of anti-rabies antibodies. The veterinarian indicated that the titre showed Russell is currently protected from contracting rabies.
- Unfortunately, no. TItres tell you antibody levels, but we don't have good data about what is actually protective. Higher is better, but we can't say a certain number is absolutely protective. Back to the NASPHV guidelines: "Titers do not directly correlate with protection because other immunologic factors also play a role in preventing rabies, and our abilities to measure and interpret those other factors are not well developed. Therefore, evidence of circulating rabies virus antibodies should not be used as a substitute for current vaccination in managing rabies exposures or determining the need for booster vaccinations in animals". That statement was echoed by North Carolina's state public health veterinarian, Dr. Carl WIlliams.
This is a tough situation. In many circumstances, home quarantine is a reasonable option. It's easier on everyone involved, by not separating the dog from the household. It's also less expensive. However, it inherently comes with some degree of risk to the household and the community. It's only a reasonable option when it's certain that people will take "strict quarantine" seriously, and truly quarantine the animal. That's hard to assess, and regulatory bodies are presumably afraid of assuming liability should they allow someone to quarantine an animal at home and something bad happens (e.g. it develops rabies and exposes people in the household, the owners take it outside where it encounters other animals or people, it escapes...). Determining whether someone can and will properly quarantine an animal isn't easy, and those issues presumably lead some people to err on the side of caution, and require formal quarantine at an approved facility.
The easiest way to avoid all this: Ensure your pets are properly vaccinated.
When it comes to public health concerns about staphylococcal bacteria from pets, most of the attention gets paid to methicillin-resistant strains like MRSA. That's not surprising considering how important MRSA is in human medicine. However, staph that aren't methicillin-resistant can also be a problem, since they can cause the same types of infections that resistant types can (they are just easier to treat). Another issue that often gets overlooked is staphylococcal food poisoning.
Staphylococcal food poisoning is one of the most common foodborne illnesses and results from growth of certain strains of staphylococci in poorly handled or stored foods. If staph get into food and the food is kept at improper temperatures, the bacteria can grow. If the strain of staph that's in the food is one that can produce enterotoxins, these toxins can accumulate in the food at high enough levels to cause food poisoning when eaten. In most cases, people are probably the origin of enterotoxin-producing staph that contaminate food, but pets are another possible source.
A recent study in Vector-borne and Zoonotic Diseases (Abdel-moein et al 2011) looked at enterotoxigenic staph in 70 dogs and 47 cats. Swabs were collected from the mouth, nose and wounds. Nasal swabs were also collected from 26 people. The researchers isolated enterotoxigenic Staphylococcus aureus (strains of S. aureus that possessed genes for enterotoxin production) from 10% of dogs and 2.1% of cats, as well as 7.7% of people. Most of the positive samples from pets were oral samples.
This study shows that dogs and cats can be potential sources of strains of S. aureus that cause food poisoning. Since the staph are often in the animals' mouths (and therefore presumably shed in saliva), animals can potentially contaminate food with these enterotoxigenic staph fairly easily, but it's unknown how often this occurs.
Prevention measures are pretty basic but should be considered, including:
- Keeping pets off kitchen counters.
- Discarding foods that pets have licked.
- Washing hands after pet contact, before handling food.
- Properly storing food, so that even if it gets contaminated with staph, the bacteria don't get the opportunity to grow and produce toxins.
- Photo from http://www.wagreflex.com/2009/06/taking-cat-ownership-to-the-next-level.html
A Minnesota woman has died of Powassan virus encephalitis, a very rare neurological disease transmitted by ticks. Powassan virus is most often found in parts of Ontario, Quebec and New Brunswick, but there is evidence of it in many other parts of North America as well, and as far away as Russia. Human infections are very rare, but when they occur neurological disease is severe, mortality rates are high, and survivors often have residual neurological problems.
Powassan virus is a flavivirus, related to St. Louis encephalitis virus and West Nile virus, but unlike these, the reservoir of Powassan virus seems to be wild small mammals, with transmission via ticks (as opposed to a bird reservoir and transmission via mosquitoes for the others). The virus has been detected in mosquitoes but it's not known whether they can transmit the virus. Ticks are considered the major (and possibly only) route of infection.
The risk to animals in areas where Powassan virus can be found is very limited. Natural infections of dogs, cats or horses have not been reported, as far as I know. However, that doesn't 100% rule out the possibility of disease, since you have to look in order to find, and specific investigation of Powassan virus transmission is uncommon. Neurological disease has been reproduced experimentally in horses, but not dogs and cats.
Overall, the risk to pet owners and pets posed by Powassan virus is very low. Taking measures to avoid ticks is the key, and such precautions should be taken for many reasons beyond Powassan virus exposure.
The more we look, the more we find when it comes to MRSA (methicillin-resistant Staphylococcus aureus). As people start looking for it in different animal species, it's often found. We've found it in many species already, including dogs, cats, rabbits, pigs, walruses, dolphins and alpacas, so it's not a big surprise to see a recent paper in the Journal of Clinical Microbiology (Ferreira et al 2011) about suspected MRSA transmission between a human and a hamster.
The case report describes a person with advanced cystic fibrosis who had undergone a lung transplant and had various other medical problems. Prior to another surgical procedure, MRSA was identified through routine pre-operative screening. Nasal and rectal swabs were then collected from the person's three pet hamsters, one of which was positive. The MRSA isolates from the human and hamster were the same, supporting transmission from one to the other. Given the person's underlying health problems, frequent contact with the healthcare system, the typical human origin of the strain that was found, and limited contact of hamsters with other animals or people, it is most likely that MRSA was transmitted from human to hamster in this case.
The paper concludes with: "Should testing of the pets of MRSA-positive patients be recommended? At this point, we recommend that MRSA-positive patients be informed that their companion animals can be potential sources of infection or reinfection. In the presence of a MRSA-positive human or animal, heightened hygiene practices should be instituted and unnecessary close contact should be avoided. Screening of household pets might be indicated in situations of recurrent MRSA infections despite adequate treatment or when immunocompromised patients live in the household."
That's consistent with our standard recommendations and hits most of the key points:
- Awareness is critical. People need to know what the risks might be and what they can do about them so that they can make informed decisions and realize why recommendations are being made.
- Testing of pets is rarely useful, particularly in the absence of a recurrent MRSA problem.
- Good hygiene practices are critical.
I don't really agree with the comment that testing of pets might be indicated when immunocompromised people are in the household (although the comment is properly hedged by saying "might be indicated"). A large percentage of the population has some degree of immunocompromise, and there's a huge spectrum from minimal risk to tremendous risk. Even in high-risk patients, screening is questionably useful to me because it doesn't really change what I'd do.
- If I screened a hamster from a high-risk person and found MRSA, I'd say that it probably came from the person, that it's possible it could be transmitted back to the person, that good hygiene practices should be followed and close contact should be restricted. There's no indication (or ability, in reality) to treat the hamster.
- If the hamster was negative, I'd say it was possibly negative because screening is not 100%, that the hamster could be exposed to MRSA from the owner at any time, and so to manage unknown colonization and reduce human-hamster transmission, I'd recommend good hygiene practices and restriction of close contact.
- If I'm going to do the same thing with a positive and negative result, I don't do a test.
This paper should be yet another reminder that we live in a complex relationship with our pets, including microbiologically. While we need to consider the role of pets in human infection (and the role of humans in pet infection), and we need to balance that with the positive aspects of pet ownership in order to maximize the benefits while minimizing the costs.
A report from India of apparent failure of rabies post-exposure prophylaxis raises a significant concern. Few details are available, but it is reported that the affected person is currently in a coma, and if that is the case, death is almost certain. This case requires careful investigation, given the almost invariably fatal nature of rabies and the assumption that proper post-exposure treatment is basically 100% effective.
From my standpoint, I'd want to confirm that:
- the person actually completed the proper treatment course (one dose of anti-rabies antibodies and a series of four rabies vaccinations over a few weeks) - the article says the course was completed but doesn't give details of what that entailed.
- proper antibody and vaccine were used.
- correct doses were administered.
- the antibody and vaccines had been handled properly (e.g. kept at required temperatures - which at times may be easier said than done in a country as hot as India).
If all of these factors are confirmed, I'd want to know whether the person had some other disease or a compromised immune system that might have prevented him/her from responding properly to vaccination.
If no underlying problem was present, I'd want to see some testing of the lots of antibody and vaccine that were administered to ensure that they were adequate.
The timeline from when the person was exposed to when he/she received the post-exposure treatment to when he/she developed clinical signs of rabies is also critical. Delaying treatment for too long can also result in treatment failure.
Undertaking such an investigation is very important because the cause for any treatment failure needs to be understood if at all possible to help prevent it from happening again.
In the same news article, another man is also reported to be in a coma due to rabies infection, because he failed to complete the full course of treatment. That's a more common problem and can be caused by lack of awareness of the importance of completing the full treatment course, inadequate communication with healthcare providers and, in some regions, shortage of vaccine.
These cases show that while post-exposure treatment is a critical aspect of rabies prevention, it shouldn't be relied on as the sole line of defense. Feral dog control, rabies vaccination of animals and education regarding bite avoidance are critical rabies-control measures that often get ignored.
An interesting study published recently in Veterinary Dermatology (Bartlett et al 2011) looked at bacterial contamination of ear cleaning solutions used on dogs at home. Ear cleaners are widely used by dog owners, but since the bottles the cleaners come in are used repeatedly and can have direct contact with the ear, there’s a chance for contamination of the bottle and/or its contents.
In this study, the researchers collected ear cleaner bottles from dog owners and cultured both the applicator tips and the contents. Bacterial contamination was detected on 10% of the bottle tips and in 2% of the solutions. The relative numbers make sense, since the tips are most likely to have contact with the ear. Regardless, this shows that a small but still reasonable percentage of bottles contain bacteria that could be inoculated into the ear.
Finding bugs is one thing, but determining if they are types that can cause disease is another. The researchers identified a few different bacteria, including Staphylococcus pseudintermedius, which is an important cause of ear infections. This isn't too surprising since the bugs that cause infection are typically those that are also normally found in (healthy) ears at low levels (and therefore the types of bugs with which cleaner bottles might have contact).
Expired ear cleaners were more often contaminated. This doesn’t necessarily mean that age leads to increased risk of contamination. It could just indicate that bottles that have been used more and over longer periods of time are more likely to become contaminated. Similarly, large bottles more often had contaminated tips, probably because of more overall use (and correspondingly more chance for contamination).
An interesting aspect was the finding that solutions containing Tris-EDTA had higher contamination rates. Tris-EDTA is a solution that is often included in ear cleaners as it has been shown to be useful for treatment of infections caused by Gram-negative bacteria.
What does this mean for people that clean their dogs’ ears? It’s hard to say. We don’t know whether a little bit of bacterial contamination poses a realistic risk. However, it’s reasonable to consider using smaller bottles and discarding them after they are used to treat a dog with an ear infection (as opposed to regular ear cleaning).
The US CDC is investigating yet another multistate outbreak of salmonellosis associated with contact with chicks and ducklings. As of June 18, 39 people have been diagnosed with Salmonella Altona infection (with a large number of others presumably infected, since only a minority of cases tend to be diagnosed). People in at least 15 states have been affected, as indicated by the map on the right.
Reported cases so far occurred between February and the end of May, but the outbreak could still be ongoing. Of all the affected individuals, 28% have been hospitalized but there have been no deaths.
Outbreaks like this lead to investigation of possible sources, starting with the usual suspects of high-risk foods and animal contact. In interviewing people that became sick, 81% of them reported having contact with live poultry before getting sick. In people that identified the type of poultry, all reported contact with chicks, ducklings or both. All 19 people that provided information about the source of chicks or ducklings reported getting them from different locations of a nationwide agriculture feed store (which is not being identified). The same strain of Salmonella was isolated from ill people and chick/duckling displays in two store locations. A single mail-order hatchery was then identified as the source of the animals.
Large distributors of animals, especially high-risk animals like chicks and ducklings, can be the sources of large outbreaks since they can supply large numbers of infected animals to a large region. While cute, chicks and ducklings are high risk for carrying Salmonella and they can shed large numbers of Salmonella in their feces without showing any signs of disease. That's why standard recommendations are that high risk persons (e.g. children less than 5 years of age, immunocompromised or elderly individuals) should avoid contact with baby poultry.
In the context of this outbreak, since the store is not being named (and since it's possible the hatchery sent chicks to other sources), anyone who has had contact with chicks and ducklings needs to be aware of the potential for Salmonella exposure. In reality, this is also true outside of the context of this outbreak, since Salmonella exposure needs to be considered after any contact with chicks and ducklings. It doesn't mean that people who have had contact with baby poultry should go to the doctor, get tested, or do anything different. However, it is important that people notify their physician about poultry contact should they get sick. For more information about reducing the risk of Salmonella exposure from poultry, click here.
In trying to keep up with technology, my lab has started adding a QR code to posters presented at research meetings. The code links to a page on the Worms & Germs Blog Resources page that houses a collection of research posters that people can view and download. You can also go directly to the poster site by clicking Research Posters on the "Topics" bar on the left side of the Worms & Germs Blog homepage, or through the Resources tab at the top of the homepage. Check back regularly to see new additions to the list.
An article in the May/June edition of Canadian Vet Newsmagazine (a magazine, not to be confused with Canadian Veterinary Journal, a scientific journal), described an interesting case of an indoor pet bird acquiring an infection from a wild raccoon, despite no direct contact.
The bird was an African Grey Parrot that was admitted to the Ontario Veterinary College because it had developed neurological abnormalities over the preceding few weeks: a head tilt, unsteadiness and problems climbing. Infection of the brain caused by the raccoon roundworm Baylisascaris procyonis was suspected and treatment was started, however unfortunately (but not surprisingly) the bird continued to deteriorate and was eventually euthanized. Baylisascaris infection was confirmed at necropsy.
Baylisascaris procyonis, the raccoon roundworm, is extremely common in raccoons, with the majority of raccoons in some areas shedding the eggs of this parasite in their feces. The eggs are extremely hardy and can survive for long periods of time in the environment. The tendency of raccoons to defecate in the same areas (raccoon latrines) means that very high concentrations of eggs can be found in some spots. While this is a raccoon-origin parasite, it can occasionally cause infection in other species (including people and dogs, albeit very rarely). After ingestion of the parasite eggs, the eggs hatch and parasite larvae migrate through the body, causing damage to various tissues as they go. If they migrate through the brain, severe neurological disease can occur.
An interesting aspect of this case is the fact that it was an indoor parrot. If this was a dog that had been exposed to a raccoon latrine, while it would have been a rare occurrence of disease, the origin of infection would have made sense. Here, the parasite eggs had to somehow make it into the house and then into the parrot. The suspected source was branches that were collected from the backyard and placed in the bird's cage. The branches were presumably contaminated with Baylisascaris eggs, and the bird ingested some while chewing on the branches.
This is a very rare situation, but the article includes some basic recommendations:
- Never adopt a raccoon (for many reasons beyond the Baylisascaris risk to pet birds).
- Don't keep parrots in outdoor enclosures where raccoons have access.
- Don't put parrots in outdoor enclosures that may have previously housed raccoons.
- Avoid putting objects from raccoon-inhabited areas into parrot cages or treat them to kill eggs. Heating objects to 62C for 1 minute should kill any eggs that are present.
- Ensure that cage bedding and bird feed are not potentially contaminated with raccoon feces.
A California teen has been battling a chronic and severe infection acquired from a fish tank. Five years ago, Hannele Cox cut her hand when she pulled it out of an aquarium. It sounds like it was a pretty minor scratch, but it doesn't take much to cause an infection under the right circumstances.
A while after the injury, infection was apparent. A round of antibiotics didn't fix it (no word on whether any bacterial cultures were performed at that point). Eventually, a dermatologist diagnosed the problem: Mycobacterium marinum infection. One problem with infections like this is that they are sometimes not diagnosed until they are quite advanced. If the patient doesn't mention the aquarium exposure and/or the physician doesn't ask about pets, an infection like M. marinum might not be considered.
Mycobacterium marinum infection is sometimes called "fish tank granuloma" in testament to its common association with fish tanks. It can be found in both freshwater and marine fish (and the water in their tanks), and most often infected fish don't have any signs of disease. Therefore, you have to assume that any fish and any aquarium could be infected, and therefore a potential source of human infection.
Infections with M. marinum usually develop a couple of weeks after exposure and are characterized by small bumps (papules) on the skin that progress to shallow ulcers. Typically, infection is not very invasive and responds to treatment, although months of treatment may be required. Sometimes, the infection can spread to deeper tissues, making it much harder to treat. Unfortunately, that's what happened to Hannele Cox. Her infection has not responded well to treatment and has spread to deeper tissues, including bone. She's had two surgeries to try to save her hand, and at least one more is planned. Amputation isn't outside of the realm of possibility, but will hopefully be avoided.
Fish owners should be aware of the risk of M. marinum infection. While fish are often ignored as a potential causes of infection and the overall risk is low, there are simple measures that can be undertaken to reduce the risk of acquiring an infection from fish tanks. These mainly involve limiting contact with fish tank water and the use of good general hygiene practices:
- Contact with aquarium water should be minimized
- Never dump aquarium water into kitchen or bathroom sinks.
- Promptly clean up any aquarium water spills.
- Take care when putting your hands in the aquarium, especially if there are sharp surfaces (e.g. rock, coral) that might result in cuts or abrasions.
- Hands should be washed thoroughly after contact with aquarium water.
- People with compromised immune systems should not have contact with aquarium water. They should have someone else clean their fish tank.
Dr. Andrew Peregrine, a veterinary parasitologist at the Ontario Veterinary College, presented some data about the types of Giardia found in dogs and cats in Ontario at this week's University of Guelph Centre for Public Health and Zoonoses annual meeting.
A lot of attention has been paid to Giardia types in recent years. That's because, contrary to earlier thoughts, it's now known that certain types (also called assemblages) of Giardia can infect multiple species while others are host specific (i.e. they only infect one species). This is very important because if a dog or cat is shedding Giardia in their stool, the type determines whether there is any risk to people.
In the Ontario study, 75 canine and 13 feline Giardia-positive fecal samples were typed. In canine samples, assemblage D accounted for 68% of samples, while assemblage C accounted for 31%. These two are dog-specific, meaning 99% of typed canine samples contained only dog-specific types and were therefore no risk to human health. The other sample contained assemblage B, a zoonotic type that infects humans and animals. In contrast, 13/13 of the feline samples were assemblage A, a zoonotic type of Giardia.
These recent Ontario data indicate a low risk of transmission of Giardia from dogs to people, but some risk from cats - at least in Ontario. It's important to note that there appears to be geographic variation in this trend. Other recent studies have reported similar results, with the predominance of dog-specific types in dogs. However, a few studies have shown a predominance of the zoonotic assemblage A in dogs. These have mainly been in low socioeconomic status areas with infrastructure challenges that could increase the chance of dogs being exposed to human feces. Therefore, it may be that in areas where there is good sanitation, dogs are most likely to get Giardia from other dogs. When there are sanitation challenges, dogs may be more likely to be exposed to human types. So, it's important to know trends in different geographic regions to understand the risk of transmission from pets to humans.
As many of you know, there was a large ringworm "outbreak" at the Newmarket (Ontario) OSPCA shelter in 2010 that led to a public outcry in response to plans to depopulate the shelter. In the aftermath of the event, an independent investigation was launched, headed by Mr. Patrick LeSage (former Chief Justice of the Ontario Superior Court) and Dr. Alan Meek (former Dean of the Ontario Veterinary College). The investigation involved a comprehensive examination of activities pertaining to the outbreak and shelter operations, in conjunction with relevant experts (disclosure: I was one of those).
The report of the investigation is now available, and covers important aspects such as whether an outbreak was actually present (short answer: no) and whether there were major problems in shelter operation (short answer: yes). Most importantly, it provides a comprehensive set of recommendations to improve the operations of the Newmarket shelter and OSPCA as a whole.
The report, in its entirety, was released today by the OSPCA and is available for download on their website. The report is on the site in multiple files: the main report is listed as "Index" and contains the ~90 page overview and recommendations. The expert reports, which might also be of interest, are tables D1-3, E, F and G.
I have no problem with people considering "alternative" therapies for the treatment of infections. I perform research on non-antibiotic alternatives and hope that results pan out in the field. I have problems, however, with people that use unproven alternative therapies in lieu of proven conventional treatment or stray from the "do no harm" philosophy.
I read an article on aromatherapy in pets that highlighted my concern. Someone can make Fluffy or Fido smell whatever they want (although my dog Meg's concept of what smells nice certainly differs from mine - she'd rather roll around on a decomposing carcass than a lavender plant). I don't think it's going to help, but it shouldn't hurt. This article went beyond that, though, talking about application of substances to treat infections. Putting tea tree oil into a dog's ear isn't aromatherapy, it's topical therapy.
Is it an issue of semantics? No.
Essential oils like tea tree oil have some powerful properties. Just because it's "natural" doesn't mean it's safe. We know that tea tree oil has antibacterial properties. However, we also know it can be toxic. There are reports of serious adverse effects in people from tea tree oil ingestion and I know of severe reactions in dogs (including 1 death) thought to be due to excessive tea tree oil application. Adverse effects can result from the dog ingesting the oil by licking it off its coat or from direct effects on the skin.
A research study presented by Dr. Becky Valentine at the 2011 North American Veterinary Dermatology Forum highlighted this concern. Her research showed that while tea tree oil was able to kill methicillin-resistant Staphylococcus pseudintermedius (MRSP), a leading cause of canine ear and skin infections, it was also quite toxic to canine skin cells. So, the cost-benefit of tea tree oil is unclear since it certainly has some toxic properties, particularly when compared to other topical therapies such as chlorhexidine, that are essentially non-toxic.
Additionally, in a good demonstration of "all pain, no gain," Dr. Valentine's research showed that grapefruit seed extract, another compound available over the counter, had no effect on MRSP but had significant toxic effects on canine skin cells.
What does this mean? It means that essential oils and any other alternative therapies need to be studied, just like any other treatment. We need safety studies to know they won't cause problems, dosage studies to know how to use them and efficacy studies to know if they work. Natural products can be quite powerful and potentially useful, but they need proper testing.
A few more details are available about the apparent case of a person surviving rabies infection that I also wrote about in a post a few days ago. The affected individual is an eight-year-old girl from Willow Creek, California. She initially had non-specific signs of illness (which is not unusual for rabies) and at her first visit to a doctor, it was thought that she probably had the flu. However, her illness progressed quickly and she developed severe neurological signs shortly thereafter. She was sent to the University of California Davis Medical Center, where she was diagnosed with rabies a week later. I'm not sure if they suspected rabies before the diagnosis and started treatment, or whether they didn't initiate treatment until after the diagnosis was made. Presumably, they started treated based on a suspicion of rabies because she would have deteriorated greatly during that week otherwise.
Her current health status isn't reported so it's not clear whether she is truly out of the woods or whether there are any residual neurological abnormalities. If treatment is successful, this girl would be only the fifth person (as far as my count goes) known to have survived rabies infection. Presumably she was treated with a form of the Milwaukee protocol, which involves putting the patient in a medically-induced coma and administering a series of anti-rabies drugs. When it was first reported to be successful, this protocol was hailed as a remarkable breakthrough in the management of rabies (which is was). However, it still has a low success rate, which is a testament to the severity of rabies and the often late recognition and initiation of treatment. Hopefully more details about the treatment protocol and her clinical status will be made available soon.
On a happy related note, Jeanna Giese, the girl who in 2004 became the first known rabies survivor in the world, graduated from College a few weeks ago at the age of 21.
As I mentioned in an earlier post, there's been a large and ongoing outbreak of salmonellosis in people across the US associated with pet aquatic frogs (such as African dwarf frogs). A recent edition of Morbidity and Mortality Weekly Reports provides an update on this large and concerning outbreak. Here are the highlights regarding infections reported between April 1, 2009 and May 10, 2011.
- 224 infections with the unique outbreak strain of Salmonella Typhimurium have been identified in 42 US states. Since it is estimated that only ~3% of Salmonella infections are laboratory confirmed, this means that the number of true cases is probably much higher (e.g. >8000, if the 3% estimate is accurate).
- The median age of affected people was 5 years, with a range of <1-67 years. The young age bias may be because of increased susceptibility to infection, increased likelihood of severe infection (which would more likely result in testing) or more common exposure.
- 30% of affected individuals were hospitalized. There were no deaths.
- 65% of affected people reported contact with frogs in the week before illness. 18% of those occurred outside the home (which is why we need to make sure that even non-pet-owners are educated about zoonotic disease risks associated with pets).
- The median time from acquiring a frog to onset of disease was 15 days. This means people often got sick fairly soon after acquiring their new pet.
- One breeder in California has been implicated as a common source of infected African dwarf frogs. As with many kinds of small pets (e.g. rodents, reptiles), this is a large breeder that sells to distributors who then sell to pet stores and elsewhere. This type of mass production and distribution system means that a problem with a single breeder can result in widespread disease. This has been clearly shown previously in various other outbreaks, especially with pet rodents.
What should the average pet owner know?
- High-risk households - those including kids under the age of five, elderly individuals, pregnant women or individuals with a compromised immune system - should not have pet aquatic frogs.
- High-risk people (as describe above) should not have contact with aquatic frogs in other places.
- People with aquatic frogs should consider the frogs to be infected with Salmonella until proven otherwise. Since we don't know how to prove otherwise, that means treat all pet aquatic frogs as infectious.
- Frog owners should avoid direct contact with the frogs and their water. Hands should be washed thoroughly after contact with frogs or their environment.
- Frog owners should never dump aquarium water into kitchen or bathroom sinks.
- Any spills of water during aquarium cleaning should be promptly and thoroughly cleaned up.
- Other pets should be kept away from aquaria (I remember when I used to have aquatic turtles and a cat. The cat used to drink from the aquarium and occasionally bat at the turtles. Not something I'd endorse now, but that was in my pre-DVM era).
This outbreak doesn't mean that aquatic frogs can't be good pets. It means that they shouldn't be pets for certain people, that good routine infection control practices need to be used by frog owners and that consideration needs to be given to whether mass production of pet frogs (and other species) is appropriate.
Photo: An African dwarf frog (Hymenochirus boettgeri) (photo credit: James Gathany, CDC Public Health Image LIbrary #11831).
Although limited on information, there's a recent report of a person with rabies in California, with some hope for survival. Rabies was apparently diagnosed in the person on May 6. Incredibly, not only is the woman alive, but she is reported to be in "stable condition" and improving at UC Davis Medical Center. That's remarkable because rabies is almost always fatal, and death usually occurs fairly quickly by the time rabies is suspected and diagnosed. Rabies survival has been reported but is extremely rare.
While it's far too early to talk about survival and cure of the woman's illness, there are many different factors that could be involved in this potentially successful treatment. These include very rapid administration of anti-rabies treatment, use of the "Milwaukee protocol" (which was the first successful treatment protocol for rabies in a person, which has also failed to be successful numerous times since), pre-existing partial immunity from previous vaccination, and/or the whims of biology and the immune system. Hopefully, this person will continue to improve and more information will be made available about why treatment has been successful so far.
The source of rabies is suspected to have been feral cats, although this is far from certain and it may be that this presumption is based on the lack of other more likely possibilities. While this is an encouraging report, it doesn't change the fact that rabies almost always kills, and it's almost 100% preventable with proper post-exposure treatment. People need to be aware of how to avoid rabies and that prompt treatment is needed anytime rabies might have been encountered.
A 35-year-old UK man has died following a seemingly innocuous dog bite. He was nipped by the family's pet dog, not during an aggressive incident but just a playful, boisterous dog. Later, he developed a fever. He saw a doctor the next day and was told that he had influenza based on his clinical signs, but no testing was done. There's no mention about whether the doctor was notified about the dog bite or asked about animal bites or contact. (I wouldn't be surprised if that didn't happen.)
Unfortunately, the man's condition deteriorated and he was diagnosed with sepsis, which is an overwhelming infection of the bloodstream. A dog-associated bacterium, Capnocytophaga canimorsus, was identified as the cause. Both of the man's leg's were amputated because of the effects of the infection, after which he started to improve, but he later developed more complications and ultimately died.
A doctor explained, "These things are so unusual. It would have been like an unstoppable train – it just depends on how the body reacts." Infection with C. canimorsus is rare, and once it's underway, it can be difficult to control. However, this quote neglects the potential treatable aspect of the infection. For an aggressive infection like this, diagnosing it early is critical. If the doctor had asked about pet contact, asked about bites, noticed the bite, or if the person had mentioned the dog bite at the first visit, an astute physician may have thought about bite-associated infection and hopefully started proper treatment, before fulminant sepsis developed. This would be particularly true for certain high-risk individuals.
Capnocytophaga infections occur almost exclusively in high-risk people, particularly people without a spleen, but also in immunocompromised individuals or alcoholics. There's no mention of whether this person had any of these risk factors, but people who do should know that they are at high risk, see a physician if they are ever bitten by an animal (even if it seems like a very minor bite), and make sure their physician knows about pet contact.
Avoiding Capnocytophaga is essentially impossible if you have a dog. It's carried in the mouths of most (if not all) dogs, but it's typically not an issue. Human infections are rare but they are important because, like in this case, they tend to be very severe when they do occur. High-risk individuals need to know about this bug, make sure their physician knows about any animal contact they have, be proactive to avoid bites and other exposure to dog saliva, thoroughly wash any bites or wounds contaminated with dog saliva, and consult a physician after any bite, regardless of how mild it may seem. Pet owners shouldn't be afraid of Capnocytophaga, but they should be aware of it and various other bite-associated pathogens, do their best to reduce the risk of bites occurring (e.g. proper training of dogs (and kids)), and know how to take care of bites.
Today (like most days) I answered questions about the potential for transmission of methicillin-resistant Staphylococcus pseudintermedius (MRSP) between people and pets. We have a long way to go before we fully understand the issues, but research continues to progress and we're learning more and more. A recent study by Dr. Engeline van Duijkeren and colleagues from Utrecht University published in Veterinary Microbiology (van Duijkeren et al. 2011) steps up our knowledge another notch.
In their study, the authors enrolled 20 households that owned pets with MRSP infections. They went into the households and collected samples from the index pet (the one with the MRSP infection), other pets, people and the household environment. At the time of sampling, 10 of the infected pets had gotten over their illness while the other 10 still had active infections.
Some highlights of the study:
- 4/14 (36%) of other dogs and 4/13 (31%) other cats in the households were MRSP carriers. In households where the pet still had an active infection, an astounding 86% of the other animals were carriers. All these numbers are much higher than the expected baseline rate of MRSP carriage by healthy pets in households, giving strong support to the notion that MRSP is being passed between pets in households with an infected pet. From an infection control standpoint, it's probably reasonable to assume that a pet living with an infected animal is a carrier.
- MRSP was isolated from 2/45 (4%) of nasal swabs from people. This is not too surprising, since we know that MRSP (and its susceptible counterpart, methicillin-susceptible S. pseudintermedius (MSSP)) can be transmitted between people and pets. This study shows us, however, that even when there is apparent MRSP transmission going on between pets in the household, it doesn't seem to commonly involve people.
- MRSP was found in the environment in 70% of houses (and 90% of household where the pet was still infected). These are pretty big numbers but are not really unexpected, since if MRSP is in and/or on animals, it's bound to be found in the environment. Whether the environment is a potential source of human or animal infection isn't known, but it's something to consider.
This research gives more evidence that MRSP can be spread readily between animals but less so between animals and people. It could be because animals have closer contact with each other in a household than with people, but a bigger factor is probably that S. pseudintermedius is more adapted to living on animals than on people.
The ever-popular methicilin-resistant Staphylococcus pseudintermedius (MRSP) owner information sheet has been updated and can be found, along with info sheets on many other topics, on the Worms & Germs Resources page.
An important concept when dealing with infectious diseases is consideration of the risk that an animal has been, or will be, exposed to a particular microorganism. Some diseases vary greatly geographically, and something that's very important in one region may be rare or non-existent in another. Good veterinarians are aware of disease trends in their area and make informed decisions about vaccination and anti-parasitic treatments based on what's happening in the area. They also know which diseases are common and which are rare or non-existent.
But that only works if the pets stay in their "home" area. Traveling with pets can result in exposure to various infectious diseases they wouldn't normally encounter. If a veterinarian doesn't know a pet travels, they can't make proper recommendations for preventive medicine.
Additionally, travel history can be very important when evaluating a sick animal, since there may be diseases that need to be considered in a traveling pet that wouldn't be an issue with a local pet. However, it's easy to overlook or forget about travel history. Pet owners need to tell their veterinarians about "recent" travel with their pets. What does recent mean? It's hard to say. For some diseases, exposure within the past few days is all that's important. For others, it may be weeks or months. So, if you have a sick pet and have traveled any time in the past year with it, it's good to mention that to your veterinarian. It may have nothing to do with the current illness, but it never hurts to let them know anyway. In some situations, it may be the critical piece of information needed to trigger thinking about a specific disease.
Some examples of diseases that may be travel-related (at least to dogs in most parts of Ontario):
- Blastomycosis, a fungal disease, tends to occur predominantly in specific areas. It's not too common elsewhere, but travel to high-risk areas puts blasto on the list of possibilities in certain cases.
- Around here, there's no indication for heartworm preventive treatment during cold winter months, but that changes if the pet goes to areas where mosquitoes hang around all year.
- Some tickborne diseases have very specific ranges that correspond to their primary hosts and certain vector species (such as birds). In Ontario, ticks are currently quite geographically focused and many dogs have little risk of exposure. Travel to one of the tick hotbed areas changes that, and means that certain tickborne diseases need to be considered.
- Canine influenza currently seems like a non-entity in Ontario. We're still looking for it but haven't found it. It is present in some places in the US, and at times, is a big problem. Travel to a place experiencing a canine flu outbreak would be a good indication to consider canine flu vaccination.
What to do?
- If you travel with your pet, part of your pre-travel checklist should be an appointment with your veterinarian to go over anything that needs to be done, be it vaccination, deworming, flea control, heartworm preventive or anything else. (It's also a good time to make sure there's nothing else going on with your pet, because you don't want a pet health crisis en route.)
- If your pet gets sick and has traveled, make sure your veterinarian knows where you went and when.
- If you travel regularly, even if it's not long distances, it's good to discuss it with your veterinarian to see if anything is required for your pet. Even if you just go a couple of hours away to a cottage regularly during the summer, you may be exposing your pet to something different.
Rabies in a lamb and cow at a petting zoo (or more accurately, in a communal group of hobby animals) has been reported in Israel. This follows identification of rabies in another lamb from the same group last week. Little is reported about possible sources of infection of these animals, at Kibbutz Neve Eitan, or how widespread human exposure may have been. It's a concern given the serious nature of rabies and the possibility that there was largely uncontrolled contact with the public, which complicates tracing of potential exposures. Given the state of rabies in Israel, the canine rabies variant is most likely the cause.
Presumably, public health and Kibbutz personnel are contacting people in the area to determine who may have had contact with the animals. Casual contact is not a risk for rabies transmission - it is only transmitted through contact of an open wound or mucous membrane (e.g. nose, mouth, eyes) with saliva from an infected animal. The risk of transmission to humans from contact with species like sheep and cattle is pretty low, however the tendency of young animals to suck on things and the fact that people often let them suck on a fingers when playing with them raises the potential for exposure. Anyone identified as having high-risk contact needs post-exposure treatment, consisting of a shot of anti-rabies antibodies and a series of four vaccines over the course of a month (unless they have been previously vaccinated against rabies, in which case they just need two booster shots).
Any animals involved in public displays, petting zoos or other events where there may be contact with the public should be vaccinated against rabies. That's particularly true in areas such as Israel, where rabies is endemic.
I received this question yesterday, pertaining to a potential therapy dog.
Valley Fever, also known as coccidioidomycosis, is a fungal infection caused by Coccidioides immitis or Coccidioides posadasi. These fungi live in the soil and are most common in the southwestern US, northern Mexico, and parts of Central and South America. They are part of an unusual group of fungi called "dimorphic fungi," meaning they exist in two forms. One form in found in the environment (soil). This arthroconidial form is the infectious form. The other yeast-like form is present in the body tissues during infection, but is not (or at least is very minimally) transmissible.
Disease from Valley Fever is rare in healthy people. These fungi are mainly a concern in people with compromised immune systems. When illness occurs, flu-like disease, respiratory disease, rash and joint pain are the most common signs, but disseminated infection (i.e. infection throughout the body) is a much more serious form of the disease that can occur.
Valley Fever is similar in dogs, with most dogs have mild to inapparent disease, and most sick dogs having vague signs and respiratory disease. Cats often develop skin lesion. Disseminated disease can also occur.
While coccidioidomycosis can occur in both humans and animals, the risk of transmission between humans and animals is extremely low. The fact that it occurs in both humans and animals is because both humans and animals get exposed to the same sources, not because they spread it between each other.
However, there is a slight risk that shouldn't be ignored. There are two situations that are of concern.
- Bites: There is one report of a bite-associated infection in a veterinary technician. The risk of infection after a bite from an infected animal isn't known, but anyone bitten by an infected animal should seek medical advice. Presumably, nothing would be done initially but there could be close monitoring for disease so that it can be treated early if problems develop.
- Veterinary procedures: Infection has been reported in a person performing a necropsy (autopsy) on an infected horse. It was thought that infectious endospores were aerosolized when an infected area was cut with a saw as part of the procedure, and inhalation of the fungus lead to disease.
There's also a theoretical concern with handling bandage material from infected animals. While the active infection would be caused by the minimally infectious tissue form of the fungus, it's possible that infectious arthroconidia could develop in a bandage.
People with infected pets have little about which to be concerned. The main risk (which is also very low) is infection from a bite from an animal with disseminated disease. Basic bite avoidance should minimize this risk, however medical care should be sought following any bite and people at high risk of serious infection (e.g. people with compromised immune systems) should take particular care when interacting with infected animals. If a pet owner has to change a bandage on an infected animal, they should wear gloves, double bag and immediately dispose of the bandage, avoid contamination of the environment during bandage changing and thoroughly wash their hands after completing the task.
Image: The infectious arthroconidia of Coccidioides immitis (source: CDC Public Health Image Library #476).
A bird specialty store owner wrote me recently, concerned about potential tuberculosis (TB) exposure. A client's bird had been diagnosed with "human TB" and that person had spent a lot of time with the bird. The source of the TB hadn't been identified, and the store owner was worried about the risk that he/she had been exposed as well.
Is it really TB?
The first thing to consider in a case like this is whether TB was really present. "Human TB" is caused by Mycobacterium tuberculosis. Birds can be infected by M. tuberculosis, but are more often infected by Mycobacterium avium complex (MAC), a related group of bacteria. Based on what the store owner wrote here, it seems that M. tuberculosis was the cause of disease.
Can TB be spread from birds to people?
Probably, but the evidence is sparse. Tuberculosis can be spread from people to birds, and it's likely it can go the opposite direction. However, close and prolonged contact is typically required for TB transmission. Human-to-bird cases tend to be birds owned by people with active TB who have close mouth-to-mouth contact with their birds (e.g. mouth-beak feeding).
What is the likelihood of transmission?
Being in the same room as a bird with TB is probably pretty low risk (just like casual contact with a person carrying TB is low risk). The risk also depends to a degree on the type of disease the bird has. If it has respiratory tract disease it is probably more likely to be shedding the bacterium in its respiratory secretions, which poses a greater risk of transmission than other forms of the disease.
Is there cause for concern?
I guess there's always some degree of concern when it comes to TB, but I assume the likelihood of transmission of TB from the bird to the store owner is quite low. The source of TB wasn't known, but most likely the bird was infected by its owner, and if so, being around the bird's owner is probably as (or more) risky.
Plague has been identified in a dog and cat from New Mexico. It’s not surprising, since plague is present in some wild animal populations in that region, but it’s still noteworthy because of the serious nature of the disease and the potential for transmission to humans.
Plague is a bacterial infection caused by Yersinia pestis. It’s carried mostly be certain types of rodents in different regions of the world, including parts of the southwestern US. It’s usually spread by fleas that bite an infected rodent and then bite a person or other animal, but it can also be spread by close contact with an infected animal. Cases in cats and dogs are uncommon, but occur in areas where plague is present in rodents, when pets have contact with infected fleas or close encounters with infected rodents (or rodent carcasses).
The latest two cases were in Santa Fe and Rio Arriba Counties in New Mexico. No details were provided about the form of plague (e.g. bubonic, pneumonic), the suspected source of infection or whether there is concern about human exposure. Finding plague in a pet is a concern for a few reasons. It indicates that plague is present in wildlife in the area, and people could be exposed from the same sources as the pets (i.e. fleas, contact with live or dead wildlife). Also, transmission of plague from pets to their caretakers can occur, particularly from cats with pneumonic plague (respiratory tract infection). Knowing that a person has had contact with a pet with plague is critical to making a prompt diagnosis. According to the World Health Organization, plague continues to infect more than 2000 people every year.
The New Mexico Department of Health has made the following recommendations:
- Avoid sick or dead rodents and rabbits, and their nests and burrows.
- Keep your pets from roaming and hunting and talk to your veterinarian about using an appropriate flea control product.
- Clean up areas near the house where rodents could live, such as woodpiles, brush piles, junk and abandoned vehicles.
- Sick pets should be examined promptly by a veterinarian.
- See your doctor about any unexplained illness involving a sudden and severe fever.
- Put hay, wood, and compost piles as far as possible from your home.
- Don’t leave your pet’s food and water where mice can get to it.
- Veterinarians and their staff are at higher risk and should take precautions when seeing suspect animal plague cases.
Photo: The vector of Yersina pestis: a flea (click image for source)
Easter is one of those holidays when there are concerns about dumb pet purchases. Spur-of-the-moment purchases of inappropriate pets can lead to animal suffering and death, and risk of human infection. Easter's problems: baby chicks and rabbits.
Rabbits can make great pets. They're a long-term commitment, but they’re relatively low maintenance, a lot is known about how to raise them and they are generally low risk for transmission of infections to people. Chicks are a different story. Chicks are notorious Salmonella vectors and have been linked to numerous outbreaks. They are easily injured and often improperly raised. They also grow up (well, some of them do, at least) to be full sized poultry, something that most people don't really want.
A story from Vidalia, Georgia highlights some of the issues with Easter pets. In it, Tracy Gunn describes his need to buy a chick for his daughter - and not just any old chick, but a dyed chick, something that’s illegal in 36 US states, but not Georgia. Gunn states "I don't know what she's going to do with it." Sounds like a recipe for a few minutes of novelty, followed by a relatively short life for the chick. At least his daughter’s 17, and not in the high risk group for salmonellosis.
Alongside the cage full of multicoloured chicks was a collection of rabbits.
“The bunnies sell real good for Easter. We've been selling a lot of them about the last month. Can't keep enough of them.” said a store employee.
He followed that up with “They buy (rabbits) for their kids for Easter, then they take Easter pictures and stuff like that with them, I'm not sure about what happens to them afterward.”
That’s the problem. Kids get a few minutes of novelty enjoyment, but then a lot of those animals end up dead, released into the wild (not a good thing) or dropped off at an animal shelter, because people don't think about the "afterward" part before they buy.
Pet purchases need to be made with thought and foresight:
- Do I really want this pet?
- Am I committed to taking care of it for its entire life?
- Can I take care of it properly with my current living situation?
- Can I afford to take care of it properly?
- How do I take care of it?
- Are there any disease risks that I need to be concerned about?
- Are there any people in the household who are at high risk for disease caused by this type of animal?
If you can't answer these questions, don't buy or adopt an animal - of any kind.
There are a number of published studies regarding methicillin-resistant Staphylococcus aureus (MRSA) carriage by veterinarians, most reporting high rates compared to the general population. This is a concern because MRSA is an important cause of disease in both people and animals. Just having MRSA living in your nose doesn't mean you're going to get sick. Indeed, around 2-3% of normal, healthy people are likely carrying MRSA at this moment. However, if you are carrying MRSA, you are at increased risk of developing an infection under certain circumstances. In veterinarians MRSA carriage is also a concern because of the potential for transmission to patients (and potentially from those patients back to people).
- 0.9% in industry and government veterinarians (who have limited contact with animals)
- 4.9% in small animals veterinarians
- 11.8% in veterinarians with horses as a major component of their caseload
- 21.5% in equine veterinarians
These results are similar to some of our earlier studies, with carriage rates in small animal veterinarians being higher than would be expected for the general population, and carriage rates in equine veterinarians being very high.
Why do veterinarians have high rates of MRSA carriage?
There's no definitive answer but there are some likely causes. Veterinarians have contact with large numbers of pets and horses, and we know these animals can carry MRSA. Even if the percentage of dogs, cats or horses carrying MRSA is very low, when you multiply that by the number of animals a veterinarian touches every week, you can see how contact with an MRSA-carrier is pretty likely. Veterinarians also tend to have close contact with sites where MRSA can be found, such as the nose. This makes the chance of having contact with the bacterium itself more likely. An additional issue the often sub-optimal use of routine infection control and hygiene practices (especially hand hygiene), which may also increase the risk of MRSA transmission. Put all these together, and it makes sense that veterinary personnel are at increased risk.
Why do carriage rates tend to be higher in equine veterinarians?
It could be because MRSA is more common in horses than small companion animals. Another plausible explanation is the fact that the horse's nose (the most likely site for MRSA to be living) is commonly touched during examination and restraint, and horses have pretty big noses to start. Additionally, good hygiene can take more effort on some farms, as sinks and often even hand sanitizer are not as readily available as they are in a clinic.
More information about MRSA in companion animals can be found on the Worms & Germs Resources page. More information about MRSA in horses can be found on our sister site, on the equIDblog Resources page.
This Worms & Germs blog entry was originally posted on equIDblog on 19-Apr-11.
A Montreal pediatrics resident has expressed concern about rat bite fever in kids. Dr. Karine Khatchadourian described three cases of this bacterial infection in a paper called "The rise of the rats: a growing paediatric issue," published last year in the journal Paediatrics and Child Health. The article didn't really present any evidence that this is a "growing" issue, but it is a disease of concern.
Rat bite fever is a bacterial infection most commonly (but not exclusively) associated with bites from rats. Healthy rats often carry the bacterium that causes the disease (Streptobacillis moniliformis in North America), and infection can occur when the bacterium is inoculated into the body by a bite, or when it's spread to mucous membranes like the mouth through direct mouth-mouth contact with pet rats (yes, some people kiss their rats).
The disease can be serious, and even fatal, if not properly diagnosed and treated. It's also a classic example of why physicians need to ask their patients about pet contact and why people need to take bites from pets seriously. Knowing that a rat is in the house, and particularly if a bite has occurred, is a key factor in helping make the diagnosis. If the physician doesn't ask the question, this critical piece of information may be missed, along with the diagnosis.
Being concerned about rat bite fever (and other zoonoses) is good, and ways to educate pet owners and physicians about such diseases are needed. However, extrapolating "rat bite fever is bad" to "rats are bad" is a stretch. The statement in the paper "Should we, as health care professionals, advocate to have rats banned from being sold in pets stores?" is over the top.
Every animal carries many microorganisms that can cause disease in people, given the right circumstances. Similarly, every person you meet is carrying something infectious. The key things to consider are:
- What is the likelihood of infection?
- How severe is the disease that may occur?
- What can be done to reduce the risk of infection?
- What is the cost-benefit, i.e. how do the potential risks compare to the potential benefits?
How can the risks be reduced?
- Rat owners need to be aware of the disease.
- Good handling practices are needed to reduce the risk of bites.
- Any bites that occur should be promptly cleaned and a physician contacted if there are concerns.
- Contact of rat saliva with broken skin or mucous membranes (e.g. kissing the rat) should be avoided.
- Physicians need to know whether their patients own pets, including rats, and know what diseases may be associated with those types of animals.
With this type of approach, the risk of infection can be reduced and the ability to properly and promptly diagnose the disease, in the odd case that it occurs, can be maximized.
I don't want to downplay rat bite fever. It certainly can cause illness, particularly in children under the age of 12. A recent paper reported a fatal case in a 14-month-old boy, however in that case the infection was associated with ferrets, not a rat.
Parents of small children need to think about the risks of zoonotic diseases, as well as injuries (e.g. bites) when deciding whether to get a pet, and what type of pet to get. If people like rats, take care of them properly and communicate well with their physician (and if their physician is aware of the issues), then the risks of serious disease are quite low.
Dr. Khatchadourian suggests that parents "should stick to cats and dogs, and steer clear of rats." However, that's no assurance that a zoonotic infection will not occur. There's no evidence indicating the risk of disease is less with those species. It doesn't even eliminate the risk of rat bite fever, since Streptobacillus moniliformis can be found in the mouths of dogs too.
Rather than banning rats from pet stores, we should focus on educating pet owners, veterinarians and physicians about zoonotic diseases.
The latest edition of CDC's Morbidity and Mortality Weekly Reports describes a case of rabies in a Michigan man from 2009. While human rabies in most developed countries is very rare, this is yet another reminder of the ever-present risk of rabies exposure in many regions, and the ongoing need to be proactive to avoid this almost invariably fatal - but almost completely preventable - disease.
In the 2009 Michigan case, the man woke one day with a bat on his arm. Bats are classic rabies vectors, and you have to assume that any bat has rabies until proven otherwise. If you can't be sure that you weren't bitten or scratched (something that may be easier said than done, because bats bites can be very tiny), then you have to consider yourself exposed if you've had contact with a bat and the bat wasn't tested and rabies-negative.
Unfortunately, the Michigan man did not seek medical attention, and nine months later he started to develop signs of rabies. It started off with pain and progressive numbness in his left hand and arm, and pain in his neck and back. He developed weakness in his left hand and soon could not grip anything or raise it more than a few inches.
While he was being evaluated in hospital, he developed breathing difficulties and had to be placed on a ventilator. Various diseases were considered and numerous tests were run. After a little initial improvement, he began to deteriorate, with more profound neurological signs.
Five days after he was admitted to hospital, his wife was asked about possible animal bites, but she didn't know of any. A couple of days later, a relative recounted being told about the bat encounter, but there was little that could be done at that point, and the man died three days later. Rabies was eventually diagnosed.
Because of the potential risk of exposure, 11 family members that may have had contact with the man's saliva received post-exposure treatment.
Sadly, you can almost guarantee that rabies could have been prevented if he had reported the bite and received post-exposure treatment (even months later). Rabies education is critical so that people know the risks of exposure and know to get medical advice after any encounter with a wild animal.
A month or two ago, there was a lot of press about the risks of pets sleeping in beds. It was in response to an article in the journal Emerging Infectious Diseases that didn't put forth any new information, but summarized a few diseases that could potentially be transmitted by pets. Unfortunately, the relative risk of those diseases wasn't really explored, and some media reports latched onto diseases like the plague, transmission of which can occur between pets and humans but the likelihood of this in most areas is essentially nil.
Anyway, an article at Scienceline.org has taken a more balanced approach towards the subject. One sentence perhaps say it best: "Many of those scare headlines, however, missed the main point of Chomel’s work: For most people, the risks are minimal, and there are easy ways to go about preventing pet-to-owner disease sharing."
I won't go into details here, since you can read the article yourself, but a key component is that pet ownership is never no-risk, but is usually low-risk. Basic hygiene practices and common sense can reduce the risks further. The cost-benefit needs to be considered, and while we can never completely eliminate the "cost" aspect, the benefits of pet ownership certainly outweigh the costs in the vast majority of households.
The US CDC is investigating a large, long-lasting and widely dispersed outbreak of salmonellosis that has been linked to contact with pet frogs, such as African dwarf frogs (see image). Between April 1, 2009 and April 5, 2011, 217 infections were identified in people in 41 states. A strain of Salmonella Typhimurium has been implicated.
Of the 217 infected people, 34% were hospitalized, which is quite a large proportion, but is probably due (at least in part) to the fact that stool samples aren't often cultured from people with milder disease (who don't go to the hospital). If you have severe diarrhea and are in hospital, you're more likely to be tested. As with most outbreaks, the 217 diagnosed cases presumably represent only the tip of the iceberg.
Of the people who got sick, 64% reported contact with frogs in the week before their illness began. Of these, 84% had contact with African dwarf frogs. This type of widespread outbreak with a single strain and a fairly clear link to a specific type of animal raises questions about whether there's a major breeder or supplier that is the source of the problem. Not surprisingly, the investigation identified a single water frog breeder in California as the source of frogs associated with this outbreak. Salmonella was identified from environmental samples at the breeder's facility. Testing is still apparently underway to confirm whether it's the outbreak strain, but it's pretty likely.
As with any other reptiles or amphibians, there are standard recommendations to avoid infections from aquatic (water) frogs:
- They should not be in households with high-risk people: children less than five years of age, the elderly, pregnant women and immunocompromised individuals.
- Care should be taken to prevent contamination of the house from aquarium/terrarium water.
- To avoid contamination, aquarium water should not be dumped down kitchen or bathroom sinks.
- Hands should be washed thoroughly after contact with aquarium water or the frogs themselves.
Photo: An African dwarf frog (Hymenochirus boettgeri) (photo credit: James Gathany).
When I give presentations to veterinarians about infection control, I often talk about legal liability as one reason they need a good infection control program. I talk about the potential bad scenarios, such as someone getting an MRSA infection from an animal and then turning around and suing the vet. I usually say something like "I don't think it's happened yet, but you never want to be an index case". I may need to change that line now that a Texas veterinary clinic is being sued over a person's MRSA infection.
However, the lawsuit, filed April 4, isn't from an owner. Rather, it's from a veterinary assistant. The woman is suing the clinic, claiming they were negligent because they didn't warn her that she would be caring for an MRSA-infected animal. She claims that she contracted the infection on the job and that it "has physically impaired her for the rest of her life."
I know nothing about this case beyond what's in the link above, however it raises a few important issues and questions.
What does this mean for the veterinary clinic?
- I've been saying for years that the bar is being raised and clinics need a good infection control program, including training and education, to reduce infections of both pets and people.
- As awareness of zoonotic diseases and veterinary infection control increases, the potential for lawsuits may similarly increase.
What level of warning is required for veterinary employees?
- This varies with the type of person.
- A veterinarian shouldn't need to be informed that they will work with animals carrying zoonotic pathogens. If they didn't pick that up in vet school, they've got some other major issues.
- A veterinary technician should have a similar understanding of the risks and measures that should be undertaken to reduce those risks.
- Lay personnel are a different story. You can't assume a lay employee has any knowledge whatsoever about infectious diseases, zoonotic diseases or infection control.
- If there are minors in the clinic (e.g. co-op students, volunteers), you need to go even farther, and there should be written notification of parents of the risks, and measures that are taken to reduce the risks.
- In general, the less the veterinary education, the greater the need for clear and documented education about disease avoidance.
How do you prove this person acquired MRSA on the job?
- That's tough. Perhaps there was a clear link with a case. Even stronger would be showing that the human and animal MRSA strains were the same, but that's unlikely to have been done. Just because MRSA can be found in animals doesn't mean that MRSA infections all come from animals. Humans are thought to be the source of the vast majority of MRSA infections and pets, and while pets can potentially spread it back to people, this is ultimately a human disease. People pick up MRSA all the time in the general population, although the percentage of people who carry it at any given time is still low.
- MRSA carriage rates have been shown to be higher in veterinarians than in the general public in a few different studies. I think it's clear that MRSA exposure is a risk of veterinary practice. However, proving that an individual infection came from a pet in a clinic is still difficult.
How can vet clinics reduce the risk of MRSA (and other) infections, as well as lawsuits?
- Have an infection control program in place.
- Make sure infection control practices and policies are written down.
- Make sure all employees are appropriately trained and document the training.
- Make sure people follow all of the required protocols.
Infection control isn't rocket science. At its heart, it's the application of some very basic practices. Infection control hasn't had a high profile in companion animal veterinary medicine in the past, but things are changing (albeit slowly). Available resources can help veterinary clinics implement a decent infection control program with minimal effort. A good resource is the document Infection Prevention and Control Best Practices for Small Animal Veterinary Clinics, which is available (free) for download on the Worms & Germs Resources page.
Heartworm is a parasitic infection (primarily of dogs) caused by Dirofilaria immitis, which is spread by mosquitoes. In areas where the parasite is present, the standard recommendation is for preventive treatment of dogs during the mosquito season, and annual testing to make sure they don't have the disease. Numerous types of heartworm medication are available, and there's been considerable debate about the potential for emergence of heartworm resistance.
In some areas, there have been increasing numbers of reports of apparent failures of heartworm preventive medication. These cases can sometimes be explained by factors such as poor compliance (e.g. the owner forgot to give the medication or did not give it properly), unnoticed vomiting/regurgitation of oral medication, or encountering an infected mosquito outside of the normal transmission period (i.e. in areas where it's a seasonal issue and medication is therefore not given year round). However, not all cases have clear explanations, and truly resistant heartworms have been identified.
Most of the concern has been focused around the inadvertent discovery of the "MP3" strain. For companies to be able to state that their product is effective against heartworm, they have to prove it in experimental studies using recent strains of the parasite. When the MP3 strain was used to test a potential new drug, they found out that it was actually resistant to the standard treatment.
A study in Veterinary Parasitology (Blagburn et al 2011) describes further testing that was done on this strain. The authors showed that only one of the four medications tested (imidacloprid/moxidectin) provided 100% protection in experimentally infected dogs with a single treatment.
At this point, there's limited information about clinical cases of resistant heartworm, and most of the anecdotal reports come from the central US. The MP3 strain itself was found in a dog from northeast Georgia in 2006. A big question is whether this is:
- a small, focal, regional issue
- a regional issue that's going to expand
- a wider but unidentified problem in many areas
There's no way to know for sure without surveillance, but it is cause for concern.
What does resistant heartworm mean to the average dog owner?
I think it means the days of being able to justify not testing dogs annually, even if it's certain that all heartworm medication has been given religiously since the last test, are over. Skipping annual testing was always a bit of a tenuous argument anyway, because of the potential for a dog to vomit or regurgitate oral medication, or to encounter an infected mosquito while not on medication, and it's even weaker now that resistance might be an issue.
Why is heartworm testing more important now?
It's important for two reasons. One is to make sure that heartworm is promptly diagnosed if it is present. This allows for earlier treatment before the parasites cause more damage. The other reason is to get information about whether resistant strains might be emerging in an area, which is helpful for the broader dog population. We have little information about the distribution of resistance, but if veterinarians start seeing heartworm cases in animals that have been properly treated with preventative medication, it's an indication that resistance might be developing in the area.
At this point, people shouldn't get too concerned about resistant heartworm, but we need to pay attention to the issue in case it increases or is in fact more widespread than we realize. Ongoing surveillance in different areas is needed to determine the scope of the problem, in terms of both the prevalence of resistant parasites and the impact on animal health. We need to be careful not to overreact, but at the same time we need to figure out what's going on. Pet owners need to have conversations with their veterinarians about the need for heartworm prevention in their pet, and the optimal approach to testing and prevention.
The title of this post describes a very basic concept, but one that is sometimes forgotten or hard to follow. The key point is that the goal of treating a sick pet is to make the pet well. Getting well and getting "normal" laboratory data aren't necessarily the same thing.
A question that comes up a lot with MRSA, MRSP and other bacterial infections is "should my pet be tested after treatment to see if the bug is gone?" The answer is usually "no."
One reason to not re-test is just what I said above. The goal of treatment is to make the patient healthy. That doesn't necessarily mean that MRSA, MRSP or whatever bug is causing the problem needs to disappear. In fact, the bacterium that causes a given infection often remains (in smaller numbers) in or on the body somewhere. If it's a skin infection, the bacterium may still be present on the skin where the infection was. However, if the body is handling it well, then it's not necessarily a problem. We have to remember that every animal (and person) has multiple types of bacteria in or on it that can cause disease given the right circumstances. We're never going to eliminate them all. In fact, trying to get rid of all potentially bad bacteria would probably result in bigger problems.
Another concept that I emphasize a lot is only do a test if you have a plan for using the result. If you don't have a clear reason to do the test, and if the result won't impact your decisions or provide information you need in the future, then why do it? While a negative culture might be nice to see, it's not necessarily a guarantee that a particular bug is gone. Furthermore, a positive culture doesn't lead to actions that are any different from those that would be taken if the culture is negative in most situations because, as mentioned above, we're looking for clinical cure (getting better) rather than microbiological cure (getting rid of the bug). Rarely would we extend treatment or do anything different in response to a positive culture in a healthy animal.
The bottom line is post-treatment cultures are rarely needed. There may be some circumstances where testing after treatment is useful and where the results would lead to a defined plan of action, but these are few and far between.
Image: A Mueller-Hinton agar culture plate being used to test the antibiotic susceptibility of a bacterial isolate according to the Kirby-Bauer method. (source: CDC Public Health Image Library #10785)
A sure sign of spring is the proliferation of classrooms hatching out chicken or duck eggs. While chicks may be cute and entertaining, they are also high-risk sources of Salmonella and some other infectious microorganisms. Numerous Salmonella outbreaks have been linked to contact with hatchling chicks, and care must be taken if teachers are considering having chicks in classrooms.
Things to consider:
- Who will be in contact with the chicks? Children under 5 years of age, pregnant women and people with compromised immune systems should not have contact with young chicks. This rules out having chicks in preschool and some kindergarten classes, however not everyone follows those standard recommendations. It's also very hard to know whether there may be immunocompromised kids in the classroom. Unless a teacher/school is sure that there are no high-risk children present, they shouldn't have high risk animals.
- Where will the chicks be hatched and raised? Is it in a contained area?
- Is the chick area easily and always supervised to ensure that rules are followed? This is important for both children and chicks, since chicks can easily be injured or killed through improper handling.
- Are protocols in place regarding safe handling and hygiene?
- Are the chicks going to be in an area where students eat?
- Are parents going to be notified in advance?
- Are there plans for sending the birds to an appropriate home when they're done in the classroom?
- Are the chicks there for a true educational purpose, or just as a novelty?
Hatching chicks can be done relatively safely in appropriate classrooms, with older children, no high-risk individuals, easy access to hand hygiene stations, appropriate protocols and proper supervision. The problem is, these aren't always (or even often) present, and inadequate thought often goes into bringing chicks into classrooms.
Like any animal, disease outbreaks can occur in wild birds. Unless they are large outbreaks they often go unnoticed, but smaller outbreaks can sometimes be encountered by homeowners with bird feeders. Because bird feeders are mixing sites for birds, they are also sites of disease transmission and a place where deaths can be identified. In an outbreak, feeders can contribute to the spread of infection between birds, and potentially be a source of infection for people or pets.
A classic example of this is Salmonella infection in songbirds. Outbreaks occur periodically and are often identified by people with bird feeders who start to find the odd dead bird in their yard. Some birds can be healthy carriers of the Salmonella bacterium (and therefore be a source of infection for others), while other birds may get sick and potentially die from the infection. If you have noted dead birds around a bird feeder, consider the potential for a disease outbreak, particularly salmonellosis.
The risk to people and pets from Salmonella outbreaks in birds is reasonably low, and probably greatest in cats. Most reports of songbird-associated salmonellosis (songbird fever) are in cats, because cats are more likely to catch and eat songbirds. Sick birds are easier to catch, further increasing the likelihood of exposure during an outbreak. Exposure is also possible through scavenging already-dead birds and perhaps from exposure to heavily contaminated surfaces or spilled feed around feeders.
General recommendations during an outbreak of salmonellosis in songbirds include:
- Keep cats indoors. This is a good idea at any time, but if you have an indoor-outdoor cat, keep it indoors if there might be an outbreak underway.
- If your pet has been exposed to a sick bird or an area where sick or dead birds have been found, and your pet gets sick, make sure you tell your veterinarian about the birds.
- Clean the bird feeder and then disinfect it by soaking it in 10% bleach for 30 minutes. Rinse it after the bleach treatment. If the feeder is difficult to properly disinfect (or you don't want to try), get rid of it by double bagging it and putting it in the garbage.
- When cleaning the feeder, do it outside so that you don't contaminate any household surfaces. When handling the feeder, wear disposable gloves and wash your hands after you remove the gloves.
- Keep the feeder down for 1-4 weeks. This reduces the concentration of birds in the area and may help reduce mingling of sick and healthy birds.
- Remove any dead birds by burying them at least two feet deep in a flowerbed (not in a vegetable garden!). This is not very easy or practical however - alternatively, double bag the bodies and put them in the garbage, avoiding direct contact with the birds and washing your hands afterward.
I get this question a lot, from both pet owners and veterinarians. Typically, my answer is "no."
- The two big questions I always ask are "why do you want to know and what would you do with the results?"
Sometimes people want to know their pet's MRSA status to see if the pet was the source of their infection.
- However, MRSA in pets is typically associated with MRSA in humans, i.e. if a pet is carrying MRSA, it probably got it from the owner or another close contact. Finding MRSA in a pet after someone is diagnosed with an MRSA infection doesn't mean the pet was the source. More likely, the person got MRSA somewhere else and passed it on to their pet.
Sometimes, people want to know if their pet is at risk of an infection.
- Carrying MRSA presumably increases the risk of an MRSA infection, but likely only in animals already at risk of an infection because of underlying disease or other risk factors such as surgery. The risk to the average pet from short-term MRSA colonization is probably limited. Also, if the pet was identified as a carrier, we wouldn't be doing anything to eliminate carriage, since we have no idea if decolonization therapy is effective in animals, and it doesn't seem to be needed (because dogs and cats almost always get rid of it on their own). Therefore, it's hard to justify screening for this reason. If the animal was getting ready to undergo surgery, then that might change my answer.
For me, it's also very important to consider what you'd do with the results of any test. In general, in a household where a person has an MRSA infection:
If the pet tests negative, I'd say that it doesn't 100% guarantee that the pet is truly negative, since no screening test is absolutely 100% sensitive. Also, the test only tells you the status of the pet at the time of sampling. It could have picked up MRSA five minutes after the swabs were taken. So, a negative result means the animal is probably negative. Since it's not absolutely negative and since the pet would be at risk of picking up MRSA from the infected person after it was tested, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose) to reduce the chance of the pet becoming colonized and to reduce the risk of MRSA transmission from pet to person if the pet was actually a carrier.
If the pet tests positive, I'd say that we certainly couldn't say the pet was the source of infection. More likely, it got it from the person with the infection. Since we know that MRSA carriage in dogs and cats is almost always transient, and that they will almost always get rid of it on their own if re-exposure is prevented, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose).
Since my response to either result would essentially be the same, why test?
Efforts are better spent on good household hygiene practices and restricting contact with high risk sites. On both pets and people, this would include the nose, as well as any sites that are infected or sites that are prone to infection (e.g. skin lesions). That's going to be much more worthwhile and rewarding than testing the pet.
This isn't an infectious disease topic but I've had a few questions about it nonetheless, so I thought it would be worth making some comments here.
With nuclear meltdown concerns in Japan, some pet owners (particularly on the west coast of the US) are flocking to veterinarians looking for potassium iodide pills for their pets. Potassium iodide is given to people (and I guess it could be given to pets) who have been exposed to radiation or who are at high risk of exposure, as a way to reduce the risk of thyroid cancer.
For pets in North America, and other regions far away from Japan, the risk of radiation exposure from the damaged nuclear power plants appears to be basically non-existent. There's no evidence that, even with a major meltdown, clinically relevant levels of radiation would reach populated areas in North America or beyond.
- Even if something unexpected happened, there are intensive monitoring efforts underway downwind (i.e. east) of Japan to detect any spike in radiation levels. There's no need to take potassium iodide weeks in advance - at-risk individuals only need it at the time of exposure.
- Also consider that if potassium iodide treatment is indicated in pets, it's also needed in people in the same area. Given the available supplies, it'd be hard to justify treating pets if there's not a full supply for all the people who might need it.
- Potassium iodide isn't a benign drug. Overdosing can cause adverse effects, and we don't have good information about appropriate doses for pets. If it was clearly needed, it would be reasonable to make an educated guess from human doses, but with no indication of need, it makes no sense to take the chance.
- Compared to humans, pets are probably at much lower risk of adverse effects from radiation exposure, because pets have much shorter lifespans, but the effects of radiation exposure tend to cause disease over very long periods of time.
What about pets in Japan? That's a different story, since there is greater potential for risk of exposure now and perhaps through food and water in the future. Still, broad use of potassium iodide isn't being recommended in Japan in humans and there's no reason to treat pets any differently. If there are regions where treatment of people is recommended and where there are adequate supplies, treatment of pets may be a good idea.
Kinkajous are strange little mammals from the Procyonidae family - the same family to which raccoons belong. Kinkajous are native to Central and South America and are occasionally kept as pets, but they don't make great pets because they are strictly nocturnal, can be cranky when woken during the day, and can sometimes be aggressive. Regardless, there is a niche pet trade, particularly in the US.
A recent report in Morbidity and Mortality Weekly Report describes detection of Baylisascaris procyonis (the raccoon roundworm) in pet kinkajous in the US, including:
- A 10-week-old kinkajou in Tennessee in which Baylisascaris procyonis was found during a routine fecal examination.
- Detection of Baylisascaris eggs from soil samples under the cages of a kinkajou breeder in Florida (the breeder from which the Tennessee animal was obtained).
- An unrelated case (11 years earlier) in which adult Baylisascaris worms were found in the intestinal tract of two adult kinkajous that died of other causes.
No human infections (i.e. cases of larval migrans) were linked to infected kinkiajous.
Baylisascaris is a parasite that's extremely common in raccoons, rare (but concerning and sometimes over-hyped) in dogs, and an extremely rare cause of disease in people. While rare in humans, it still gets a lot of attention because when disease does occur, it can cause serious neurological damage, typically in children. The damage is caused by migration of parasite larvae through the body, and through the brain. This can occur after someone swallows infective parasite eggs, which then hatch in the intestinal tract and then embark on their journey through the body.
It's unclear whether Baylisascaris is a common problem in kinkajous (like it is in raccoons) or a rare finding (like it is in dogs), since this report only describes the parasite in a small number of animals, and no larger studies of intestinal parasites in kinkajous have been reported. It would be useful to know whether kinkajous are true reservoirs of this parasite (and therefore whether we should consider all kinkajous to be carriers) or whether infection is just an unusual finding.
Overall, the public health risk is likely limited.
- There aren't that many pet kinkajous around, as far as I know.
- While Baylisascaris is nothing to dismiss, to get infected, a person still has to eat infective eggs from feces. The likelihood of transmission from a pet to a person is therefore low if good basic hygiene measures are used.
- The parasite eggs are not immediately infectious. They have to sit around in the environment before they are infectious, usually for 2-4 weeks. Therefore, prompt removal of feces and careful attention to basic practices like hand hygiene should greatly reduce the risk of transmission.
- Routine testing and deworming of pet kinkajous should reduce the risk even further.
What does this mean for pet kinkajou owners? Not a lot beyond what would normally be recommended. Pet kinkajous should have good veterinary care and regular fecal examinations. Regular deworming should be discussed with the attending veterinarian, and good hygiene practices should be used to avoid contact with feces, especially old feces.
- Like all mammals, donkeys are susceptible to rabies virus but infections are not particularly common. Raccoon rabies has also be identified in the area, and a bite from a raccoon may have been the source.
- A York County woman was bitten by a kitten that ran into her house when the door was opened for someone else. The kitten bit her when she grabbed it to throw it (hopefully not violently) back outside... an understandable reaction but not what you want to do in a case like this. You need to know whether a wild animal that bites is rabid, and if it gets away, you can't test it. You need to get away from it but keep it contained until someone can come get it. The other problem with people getting rid of the animal is that they might not recognize the risk of rabies. In this case, the kitten was hit by a car after being removed from the house, which allowed for it to be tested.
Yet another report of a dog being exposed to rabies through contact with wildlife, then being euthanized because it was not properly vaccinated.
- An unvaccinated animal that has been exposed to a rabid animal has to be euthanized or undergo a strict six-month quarantine. A vaccinated animal only needs a 45-day observation at home.
- Encountering a manic bobcat isn't something I'd like to do, and a LaCrosse, Florida woman spent nine days in hospital after being attacked by one. The 25-pound cat was trying to get the family's cat, then lunged at the woman when she came outside the house, aiming for her neck. Her husband then shot it. They knew that the bobcat needed to be examined, and took the rather unusual approach of bringing it to the hospital emergency room with them (I'd love to have seen that). I don't imagine hospital personnel did anything, but Florida Fish and Wildlife Conservation Commission personnel came and got it, and later confirmed that it was rabid. (Image: Lynx rufus, US Fish & Wildlife Service)
Raccoons are fascinating critters but they don't make good pets. Their curiosity makes them quite disruptive and damaging, and they have seriously injured people (particularly infants). They are also rabies vectors, and in many regions raccoon ownership (along with other wildlife species) is illegal (or only legal with a license). Despite all this, some people continue to keep raccoons as pets, and injuries continue to happen. Unfortunately, it's often not the owners that suffer the consequences, but children.
A one-week-old Griggville, Illinois baby is in hospital after being attacked by her grandparents' pet raccoon. The baby was in a room with the raccoon (not a good idea to start with), when the raccoon starting biting and scratching the baby's face and head. The raccoon's owner thinks the raccoon wasn't being vicious, just curious and trying to get a ribbon off of the baby.
"Rampy was trying to get the bow off the baby's head and it's got long claws and he was scratching up the head trying to get the bow off," said the owner.
Regardless, the fact that it caused severe injury indicates it's a hazard. (Wounds caused by accidents heal at the same rates as those caused my malice.)
Euthanasia of the raccoon was requested to test it for rabies. The owner countered that it had been vaccinated against rabies and dewormed (which raises the question of what veterinarian did this. I'd consider vaccinating and deworming an illegal pet unethical at best). Further, rabies vaccination does not guarantee that the raccoon isn't rabid. A judge eventually ordered the raccoon to be euthanized.
You'd think the raccoon's owners would be aghast at the attack. While I can see how they'd be attached to their pet, typically concern over a grandchild takes precedence. Not here, however, as the owners fought the euthanasia order and are railing against local authorities for having the raccoon euthanized after a potentially life-threatening attack. Even the infant's father is taken back by their attitude, stating "If it was somebody's dog that bit a kid, they'd be held accountable. These people should be held accountable for [the raccoon]."
Jones Natural Chews Company has recalled 2705 boxes of pig ear treats because of a "potential" for contamination with Salmonella. The recall was the result of a routine sampling program by the Washington State Department of Agriculture which revealed that the finished products contained the bacteria.
This shouldn't come as a surprise. Salmonella contamination of raw animal-based pet treats is nothing new, and contaminated treats have been implicated in outbreaks of human salmonellosis. There is a risk to pets as well, since Salmonella can cause disease ranging from mild to fatal. Typically, dogs that eat a little Salmonella don't get sick, but they may under the right circumstances, and even dogs that appear healthy can potentially infect people they are around. Handling the treats is also a risk to people, especially the very young, very old, pregnant women and people with compromised immune systems. Households with any individuals from these groups should avoid having any raw animal-based treats around (unless irradiated). Anyone having contact with treats (whether they're in a high-risk group or not) should wash their hands afterwards.
When a particular animal species or breed gets a lot of attention, such as through a popular movie or TV show, there's sometimes a major increase in people wanting one as a pet. The proliferation of Dalmatians after 101 Dalmatians, and people buying Jack Russell terriers in response to Eddie from Frasier are only two examples. Sometimes the trend is fine, but it can result in problems when people get breeds or species that really aren't right for them (this was a big problem with the Dalmatians), and with puppy mills pumping out large numbers of poor quality animals to meet the demand. The problems can be even worse when an exotic species is involved.
Concern has been expressed about the potential for this to occur following the success of the animated movie Rango. The movie features a chameleon, a fascinating reptile but also one that is not that easy to properly maintain in captivity and, like all reptiles, carries a risk of Salmonella transmission to household members.
PETA and some other groups have expressed concern about a PetSmart promotion whereby people can get a $10 discount on reptiles if they bring in a Rango movie ticket stubs.
Any increase in demand for chameleons resulting from this promotion will be trouble, because:
- Odds are most of the animals will not do well if purchased on a whim by someone who isn't adequately prepared to take care of them.
- Smuggling or legal importation of wild-caught chameleons will probably increase, with the associated very high death rates during the collection and shipping process.
- Chameleons may end up in households where reptiles are not appropriate, such as those with kids under five years of age, elderly individuals, pregnant women or people with compromised immune systems.
Hopefully the concerns are unfounded, but anyone considering purchasing a chameleon needs to carefully research the care requirements, be aware of the risk of disease transmission in the household, and should look for ethically sourced (i.e. captive bred and properly raised) animals.
The CDC's Morbidity and Mortality Weekly Reports has a short report about two plague cases in the US. Plague, while often thought of as a historical disease (the Black Death), is alive and well in wild rodents in some areas of the world, including parts of North America, and human cases continue to occur.
Here are highlights of the CDC report (in italics) with some extra comments.
Plague, caused by Yersinia pestis, is enzootic (present in the population, typically at a low level) among rodents in the western United States. Humans can be infected through 1) the bite of an infected flea carried by a rodent or, rarely, other animals, 2) direct contact with contaminated tissues, or 3) in rare cases, inhalation of respiratory secretions from infected persons or animals. In September 2010, the Oregon Health Authority reported the first two cases of human plague in Oregon since 1995 and the only two U.S. cases in 2010.
Both illnesses began on August 21. The patients, aged 17 and 42 years, lived in the same household and might have been exposed to plague by infected fleas from one of their dogs; that dog was found to be seropositive for Y. pestis by the passive hemagglutination-inhibition assay (dilution of 1:64). One patient acknowledged sleeping in the same bed with the dog during the 2 weeks before illness onset. Both patients had high fever and multiple bilateral inguinal buboes; one patient had hypotension, tachycardia, and acute renal failure and was hospitalized. A gram-negative rod with bipolar staining was isolated from a specimen of that patient's blood.
...25 days after specimen collection, the isolate was identified as Y. pestis... Both patients recovered uneventfully after empiric therapy with doxycycline and amoxicillin clavulanate potassium, respectively, although the latter is not considered effective in treating plague.
Plague is a Category A potential bioterrorism agent. Human infections are rare but can be life-threatening. The plague case-fatality rate depends on the clinical presentation (i.e., bubonic, septicemic, or pneumonic) and timing of antibiotic therapy initiation; if untreated, the case-fatality rate is >50% for bubonic plague and approaches 100% for pneumonic plague. Rapid laboratory identification can help guide therapy.
Sleeping in the same bed with dogs has been associated with plague in enzootic areas. Plague patients with no history of exposure to rodents can be infected by Y. pestis if their pets carry infected rodent fleas into the home. Veterinarians always should recommend flea control to dog and cat owners.
This is an example of a situation where pets can play a role in human infection while not being the direct source of infection. While direct pet-human transmission can occur, this typically involves situations where someone has close contact with a pet that is sick with the plague. Most often, this kind of transmission is associated with close contact with cats with pneumonic (respiratory) plague.
Key aspects of reducing the risk of pet-associated plague in areas where plague is, or may be, present, are:
- Preventing contact of pets with wildlife, living or dead.
- Preventing roaming of pets in the wild.
- Discouraging wildlife from living in or around homes.
- Keeping cats indoors.
- Routine flea control.
More information on plague and pets is available in our archives.
In Canada, rabies testing and surveillance is performed by the Canadian Food Inspection Agency (CFIA). National data for 2010 are now available and indicate there were a small number of cases in domestic animals, with more in wildlife, for a total of 123 cases.
Dogs: There were three cases, all in Saskatchewan.
Cats: Four cases, three in Manitoba and one in Alberta.
Horses: One rabid horse in Manitoba.
Cattle: One, from Manitoba.
Skunks: 60 cases, 33 in Manitoba, 17 in Saskatchewan and 10 in Ontario.
Bats: 48 rabid bats, most in Ontario (29) but also in BC, Alberta, Saskatchewan, Manitoba, Quebec, New Brunswick and Nova Scotia.
Foxes: Six from the Northwest Territories or Nunavut.
No rabid sheep, goats, raccoons (down from 58 in 2007), wolves or other species.
Manitoba seems to win the 2010 rabies prize, while Newfoundland and Labrador, Prince Edward Island and the Yukon had no cases.
As with any disease surveillance, these numbers underestimate the scope of rabies. For an animal to appear on the list, rabies had to be considered and testing performed. So, for wildlife, it's a massive underestimation of the number of cases, since most affected wildlife don't get tested. Wildlife testing (and testing in general) is typically only done when there has been the potential for human exposure. Domestic animal cases are probably a fairly close representation of the status of rabies in pet and farm animals, since it's reasonably likely that a domestic animal with rabies would be identified as such and tested (although certainly cases can be missed or neglected). As with wildlife, there is probably an under-identification of rabies in feral/stray dogs and cats, since testing would only be done on these animals if they are caught and if there was potential human exposure.
- No? Maybe only if you're a high school wrestler from North Dakota.
On the way to the finals of a tournament, a busload of wrestlers came across a "dead" raccoon. For reasons that are unclear, they thought it would be a good idea to pick up the raccoon carcass and take it with them. They put it in the storage area of their bus and continued on their way.
Not only did that group of students display some questionable judgment by picking up the carcass, they also failed to notice that their "dead" raccoon was not actually dead. When they arrived at the tournament, the raccoon got up and ran away.
So, not particularly bright (or observant), but maybe not that big of a deal. Raccoons are important rabies vectors and a raccoon that allows itself to be loaded onto a bus by a bunch of high school students, and then later runs away, must be considered potentially rabid since you can't prove otherwise. However, you don't get exposed to rabies just by riding in the same bus as a napping raccoon. You have to have close contact with it (e.g. bite that breaks the skin, exposure of an open scratch/wound or mucous membrane (nose, mouth, eyes) to raccoon saliva).
In this case, however, the team was removed from the tournament when officials found out "they had been in contact with the wild animal and feared they may have contracted rabies." This makes no sense.
- If they were exposed, they'd pose no risk to anyone else at that point. You don't become immediately infectious after exposure. These students could not have transmitted the virus to other competitors.
- There was no evidence that they were actually exposed. No one was bitten or scratched.
Carrington school superintendent Brian Duchscherer said: "Once we found out, we didn't know if there was a potential of spreading anything or if the raccoon had rabies or not but we decided to bring our kids home." I would hope that a quick call to public health would have put those concerns to rest. Either they didn't bother to try to get good information or they got bad advice.
An Irish study has reported a high rate of Salmonella contamination in pig ear treats. Various earlier studies have identified Salmonella in pig ear treats, and human infections have been associated with contact with such treats. Recommendations for processing and handling of pig ear treats have been made and have hopefully reduced the likelihood of contamination, but there's no information about adherence to these recommendations.
In the most recent study, published in Food Research International (Adley et al. 2011), researchers purchased 102 pig ears from 4 pet shops in Limerick City, Ireland. Salmonella was detected in 28% of samples. A variety of different Salmonella types were found, including antibiotic resistant strains and types that are common causes of disease in people.
Interestingly, all of the contaminated treats were from 2 of the 4 stores. The two negative stores only sold treats sourced from within the European Union, and one of them only sold pre-packaged treats. The other two stores sold treats sourced from the EU and Brazil, and sold some in bulk bins. All positive treats were from the same distributor, and all were from bulk bins.
The high prevalence of Salmonella in these treats is concerning, particularly in light of standard guidelines for processing such treats and and EU regulation that if treats are not Salmonella-free, they must have less than 1 Salmonella bacterium per 25 g of product.
Contamination of bulk bin treats isn't surprising, as I mentioned in a post just the other day. Bulk bins allow for cross contamination, and a single positive treat (or a single contaminated hand going into the bin) can result in contamination of many other treats. Also, picking treats out of a bulk bin can potentially contaminate consumers' hands, and there's an additional concern that bulk bins are often kept at a level where young children (a high risk group) can access them.
Contact with Salmonella in pig ear treats is a risk, and people should wash their hands after any contact with a pet treat. Avoiding bulk bin treats is a good idea. Purchasing irradiated and individually packaged treats should also help reduce the risk. Unfortunately, stores do a lousy job of notifying people about the risk. As the paper states "We recommend public awareness advertising in pet shops to alert pet owners of the risks associated with pig ear pet treats and hygiene practices that should be followed."
Merrick Pet Care has recalled Junior Texas Taffy pet treats because of the potential for contamination with Salmonella. No illnesses have been reported but contamination of treats could pose a risk to both pets and owners.
Contamination of pet treats is not uncommonly reported, but the overall scope of the problem isn't well understood. Outbreaks of salmonellosis in people have been reported in association with handling contaminated treats. The impact on animal health is unclear. Most recalls are not associated with reports of animal illness, however it's possible that small numbers of sporadic cases of disease would not be identified or reported.
Recalls like this highlight the potential risk from any pet treat or pet food. You can never absolutely eliminate risk but you can do things that will probably reduce the risk and identify situations where there are greater concerns.
- Packaged treats may be lower risk than treats from bulk-bins, because a single contaminated item can lead to cross contamination of many others in these large bins.
- Individually packaged irradiated treats are presumably of little to no risk.
- "Human-grade," "premium" or other catchy descriptions have absolutely no meaning with regard to food safety.
- People should wash their hands or use a hand sanitizer after handling treats.
- Care should be taken when handling any animal-based pet treats, particularly in households that include people with compromised immune systems, infants, elderly individuals or pregnant women. In these households, particular attention needs to be paid to handwashing after contact with treats, or - better yet - avoiding treats (or at least non-irradiated treats) altogether.
Glanders, a very serious disease of horses, donkeys and mules caused by infection with the bacterium Burkholderia mallei, has made the news again in a rather unusual manner – it has been reported as the cause of an outbreak in lions and a tiger at an Iranian zoo in Tehran.
The story goes that two Amur tigers arrived at the Tehran zoo from Eastern Russia in April 2010 as part of an exchange program between the two countries. The tigers were supposed to be used to help restore the tiger population in northern Iran on the Miankaleh nature reserve, but their living quarters there were apparently still not ready, and thus they were being kept at the zoo. One of the tigers died in December 2010.
And that’s were the story starts to get a little dicey. The Iranians claim the tigers were imported already carrying the disease, and that the last case of glanders at the zoo was 50 years ago. The tigers had already been at the zoo for eight months - although the incubation period for glanders can be months in some cases, it is normally only weeks. The Russians of course insist that the tigers were completely healthy when they were transferred – they’d been thoroughly examined and quarantined prior to being moved. (This makes the most sense to me, since transporting an animal such a long distance is a major stress and increases the risk of illness, and transporting an animal that is already sick would be even more risky. Not a chance I would take with two members of a species of which there are fewer than 900 individuals left in the world.) They also pointed out that a sick tiger from the cold regions of Russia would be much more likely to succumb to illness during the very hot Iranian summer, not during the winter.
Another report said that three lions at the zoo also died from glanders in the last two months, and subsequently another 14 lions were diagnosed with the disease, all of which were put down by the authorities. The main concern seemed to be the spread of the disease from the big cats to the feral cat population, and then to the human population. This second report states that “the tiger died after being fed contaminated meat, though it is possible it could also be related to the glanders.” Yet another report said that the tiger was infected with feline immunodeficiency virus (FIV - the feline equivalent of HIV).
Facts to keep in mind:
- Glanders is an highly contagious disease, and highly fatal (B. mallei is even classified as a Class B bioterrorism agent).
- Animals that do recover from the disease can become long-term carriers of B. mallei, and are a risk to other animals (and people). Prompt euthanasia of affected animals is therefore often the primary means of controlling outbreaks (but the bacterium is susceptible to antibiotics).
- The infection can be transmitted to other animals (and people), usually through close direct contact or contact with oral and nasal secretions and discharge from skin ulcers. It can also be transmitted by eating tissues from infected animals.
- The bacterium is killed by most disinfectants, and UV radiation (sunlight).
Glanders can affect species other than equids, including people and cats, however there is very little information available about glanders in any felids, let alone lions and tigers. Theoretically it might be possible for the disease to spread from the zoo animals to feral cats and then to people, but I don’t know how many feral cats are brave (or stupid) enough to wander into a lion enclosure. There’s also a possibility that a glanders-positive feral cat may have infected the zoo cats (but again, it would have to be very brave, or very stupid). It is also unclear what tests were used to confirm that the big cats were infected with glanders, and it is unknown if other animals at the zoo have been tested. Since this is typically a disease of equids (and has also been found in goats and camels), I would certainly be checking these animals first.
The big question is, where did the glanders come from in the first place? It seems unlikely that the tigers brought it from Russia, when the disease is actually endemic in Iran (even though they’d had no diagnosed cases at the zoo for many years). Is there a carrier animal in the zoo? Were the animals infected by eating contaminated meat? Was it brought in by feral cats? The source needs to be identified and addressed or animals will continue to be infected, which is particularly bad news for the kinds of rare species that may be found in a zoological collection. Some more details about the testing would also be appreciated – given the severity of this disease, and the severity of the consequences for positive animals (euthanasia), one needs to be as sure as possible that these animals are infected with B. mallei and not something else.
Photo: Amur Tiger (Panthera tigris ssp. altaica) (click image for source)
Cowpox virus is an example of a virus with a misleading name. It's place in history is from Jenner's observation that milkmaids who had been infected with cowpox were resistant to smallpox, leading to the use of cowpox (which causes very mild disease) to protect against smallpox (which is very, very bad). While cattle can be infected, they are not the true host of this virus, and infections in cattle are actually quite rare.
Various rodents are the true reservoir of cowpox. Other species can be infected from contact with