All animals pose some risk of infection to people, to one degree or another, but the risk varies a lot between animal species. I guess I’ve always considered guinea pigs to be relatively benig, with a few zoonotic disease concerns but with bites probably being the biggest risk.
I still think that’s true, but a couple of recent studies show that there are a few other things to to keep in mind.
A paper coming out in January’s edition of Emerging Infectious Diseases (Gruszynski et al., Streptococcus equi subsp zooepidemicus infections associated with guinea pigs) describes infections caused by a bacterium, commonly known as Strep zoo, that is typically found in horses, and occasionally in other species like dogs.
The first case was an adult in Virginia who started off with flu-like disease and then deteriorated, developing a serious systemic infection, shock and necrotizing fasciitis (flesh eating disease). Strep zoo was isolated from the patient's wounds. He spent several months in hospital and a rehabilitation centre, but survived.
The second patient was an elderly man, also from Virginia, who was related to the first patient. He went to the hospital with vague, predominantly flu-like signs, and developed pneumonia, septic shock and multi-organ failure. Strep zoo was isolated from his bloodstream. He was hospitalized for 18 days but survived.
Two infections by the same bug in people who have contact with each other certainly suggests there’s a common source or one infected the other. But where do guinea pigs come into this story?
A relative of the first patient mentioned that he had recently purchased four guinea pigs, and that one had died shortly thereafter. The second patient had cleaned the guinea pig cage a couple of days before he became ill. So, it was logical to consider the guinea pigs as a possible source. Unfortunately the response was over-the-top. They euthanized all the guinea pigs and then tested them. Strep zoo was found in two of the guinea pigs, and the guinea pig and human isolates were indistinguishable. Presumably, the pigs were infected first and passed it to the two people through regular contact.
What does this mean, in the grand scheme of things?
- Probably nothing major.
- It’s a reminder that infections (including serious ones) can result from even normal contact with species we don’t often consider to be high risk.
- It shows the importance of physicians querying pet contact.
- It highlights the need for good basic infection control and hygiene practices around animals.
It also shows the common, but what I’d consider to be excessive, response that can occur when people finally do consider an animal source. It’s not clear whether the pigs were euthanized at the owner’s direction or whether public health pushed for it.
Euthanasia is the easy way out, since it removes any need to think about ongoing risk (euthanizing the animals before even testing them makes no sense at all to me). If the owner wasn’t going to take them back (or their interim caretaker wasn’t comfortable keeping them) and they were unwilling to re-home the pigs because of fear of infecting someone else, I can see how that decision would be made. It’s a stressful time when people are sick, and the fear of it happening again would be understandable.
- This bacterium is a rare cause of disease, and some people (e.g. horse owners) are exposed to it quite regularly.
- It might only be present in the guinea pigs for a short period of time. We don’t know if they can be long-term carriers, and it’s possible they would get rid of it after a short period of time in a household (versus a stressful breeding colony or pet store environment).
- Strep zoo-free guinea pigs would still pose some risk.
There’s never a simple answer for situations like this, and the full story would be interesting to know.
As I mentioned a few days ago, eliminating the risk of rabies in animal shelters is pretty much impossible. Another shelter-associated rabies exposure situation highlights the problems.
A cat at the Washington Area Humane Society was recently diagnosed with rabies, resulting in three people receiving post-exposure prophylaxis (i.e. rabies antibodies and a series of rabies vaccines). What’s quite interesting here is the fact that the cat had been in the shelter since May. So, unless the cat was exposed to rabies in the shelter (possible, but very unlikely), that means the incubation period was at least 6-7 months. That’s not unheard of, but it’s pretty long for a cat. We don’t know exactly how long the incubation period can be, except that it’s long. In humans, cases have been identified a few years after the presumed exposure. This situation shows how the 6 month quarantine that is used after exposure of unvaccinated animals is very reasonable, but still not a guarantee. It also shows how short-term isolation of animals in a shelter after arrival can’t guarantee there will be no rabies exposure (although it’s good for many other reasons).
Yes, that’s an "oops," but it’s also not completely preventable.
A stray dog and her 6 puppies were sent to a foster home recently by a South Boston, VA animal shelter. It’s a common and logical thing to do, to get the puppies into a lower risk environment until they are old enough to be adopted. However, any animal with an unknown history is a risk, and that was a problem here, because the dog started to act abnormally after being fostered. She was subsequently diagnosed with rabies, and seven people (including, not surprisingly, the foster family) had to receive post-exposure prophylaxis.
Here are some comments from the article:
It takes about 10 days for an animal to start showing signs of rabies. Staff at the pound had no clue that the dog had rabies because it only stayed there for two hours.
The first point is incorrect. It can take much longer for an animal to develop signs of rabies. The 10 day window is what is used after an animal has bitten a person, because an animal that is shedding the virus will become ill with rabies within 10 days. However, the incubation time (i.e. the time from when an animal is exposed to the time it develops disease) can be months. So, a 10 day quarantine of new arrivals is good for some things, but doesn’t mean that the dog won’t develop signs of rabies later.
Staff sanitized the area.
This isn't really needed for rabies, because the rabies virus isn’t spread through contact with the general environment. It is certainly a good practice for the shelter overall, though, since there are presumably many other bacteria and viruses lurking in the shelter environment.
When an animal is brought in now, it’s monitored for signs of any disease.
That’s a common (and common sense) measure. However, it only helps with some, but not all, diseases. In this particular case, it may have helped the staff to identify this dog as being rabid before it was sent to a foster home (because it developed signs in less than two day), but it won’t prevent all cases like this from occurring. It’s a tough balance between monitoring for signs of disease and wanting to get the animal out of the shelter ASAP (because of shelter space issues, and to reduce the chance of the animal being exposed to something in the shelter, etc.). There’s no perfect approach.
“People need to get their dogs and cats vaccinated. You’re playing Russian Roulette when you turn the cat out at night and it doesn’t have the vaccine,” said Dan Richardson, the Environmental Health Manager for Southern Virginia.
Amen to that.
A recent paper in Zoonoses and Public Health (Whitten et al, 2014) describes reptile-associated salmonellosis cases in Minnesota between 1996-2011. Like similar reports, the data underestimate the problem because it’s thought that for every documented case, approximately 30 cases go undiagnosed. Regardless, there are some useful findings.
Twelve to 30 cases of reptile-associated salmonellosis were identified in the state each year. That represented about 3.5% of all sporadic (non-outbreak-associated) cases.
- This is lower than is often reported, but Minnesota is also known to have one of the lowest pet ownership rates among states, which might account for this discrepancy, at least in part.
Kids bore the brunt of disease (as is normal), with the median age of victims being 11 years. 17% were less than one year of age, 31% were less than five years of age, and 67% were under 20.
- The very young kids presumably had little or no direct contact with reptiles. This highlights the fact that living in the house with a reptile is a risk factor, even if there’s no direct contact. That’s why reptiles shouldn’t be in the house if there are high risk people present (i.e. kids less than five years of age, elderly individuals, pregnant women, immunocompromised individuals). Just trying to keep the high risk people from having contact with the reptile isn’t enough.
23% of cases had to be hospitalized. Fifteen (5%) had invasive infections, where Salmonella made it out of the intestinal tract and into the rest of the body.
- These types of infection are a major concern, and the report included one case where the bacterium was found in the cerebrospinal fluid (indicating the person presumably had Salmonella meningitis).
Fortunately, none died.
Over half of the people who got sick and who were asked (i.e. not including the young kids) reported knowing that reptiles can be sources of Salmonella.
Almost half reported exposure to a lizard, with 20% reporting snake contact, 19% reporting turtle contact and some reporting contact with more than one type of reptile.
A quarter of those who reported turtle contact and indicated the size of the turtle said the turtle was less than four inches in length.
- That’s relevant because it’s illegal to sell turtles that small in the US. The rule was put in place due to the increased risk of kids handling small turtles and getting exposed to Salmonella. The finding isn't surprising, though, since this law is widely ignored.
Some people consented to having their reptile tested. 86% of the tested reptiles were shedding Salmonella at the time the follow-up was performed. 96% of those were the same strain that caused disease in the person.
Overall, not a lot has changed, which is concerning. There’s a risk of disease with any pet contact, but reptiles are undeniably high risk. We’ll never completely eliminate the problem, but logical pet ownership and animal management are needed to reduce the risk. A good start is getting young kids away from reptiles. Reptiles can make great pets… but not for young kids, and not without some risk.
I’ve written a lot lately about importation of pets and associated infectious disease issues. A recent paper in the journal Zoonoses and Public Health (Sinclair et al, Dogs entering the United States from rabies-endemic countries, 2011-2012) provides some interesting data on this topic.
Dogs entering the US from countries where rabies is present must be vaccinated against this disease. If they are not vaccinated, the importer must sign an agreement that says the dog will be confined until it is fully vaccinated, i.e. 30 days after it receives its first vaccine. Dogs have to be at least 3 months old to be vaccinated, so any dog under that age must be confined until it is 3 months old, vaccinated, and then confined for an additional 30 days post-vaccine.
The study focused on dogs that had to be confined due to lack of rabies vaccination on entry to the US.
- Over a 1 yr period, 2746 dogs were confined. That's a pretty impressive number of imported dogs considering this only accounts for unvaccinated dogs from countries where rabies is present.
- Dogs originated from 81 different countries. Canada (21%), Mexico (13%) and Europe (30%) were the most common sources. Dogs from Mexico would be the greatest concern of these because of the presence of canine rabies in that country. Europe is variable risk, with rabies in wildlife and dogs imported from higher risk regions. It’s not clear to me whether some of these "European" dogs might have actually originated elsewhere and been funneled through Europe, which would make them higher risk as well.
- 11.4% of the dogs came from South America, 8.5% from Asia and 1.2% from Africa. These are all higher risk regions.
- Most (67%) were puppies less than 3 months of age (so too young to have been vaccinated.)
- The nature of the movement of the dogs (e.g. how they arrived, where they arrived, from where they came) in comparison to human travel patterns led the authors to conclude that most were "entering the United States for increasing the dog supply", as opposed to people traveling with their own pets.
One of their other conclusions was “Dogs unimmunized against rabies and coming from rabies- endemic countries (i.e. DPCAs) continue to be imported into the United States in considerable numbers. These DPCAs pose a demonstrated risk for re-introduction of canine rabies virus variant and may also pose risks for entry of other animal and zoonotic diseases.“
If over 2700 unvaccinated dogs were brought into the country, how many dogs were brought in in total? How many of the "vaccinated" dogs were really vaccinated? (Since scrutiny is limited and faking a vaccine certificate doesn’t exactly take a lot of effort.) What other pathogens might those thousands of imported dogs been carrying? Finally, why import those dogs in the first place? There’s hardly a shortage of dogs looking for homes in the US...
No, not really. Just for the sake of training.
The ongoing Ebola epidemic in West Africa, along with a few "escapes" of the virus into other regions, has brought scrutiny on the potential role of animals (beyond the wildlife reservoirs) in Ebola virus transmission. Concerns have led to development of contingency practices in some regions for handling potentially exposed animals (just in case).
Today, we ran a trial retrieval of an Ebola-exposed dog (played by Merlin) from a household to evaluate and practice our retrieval, transportation and quarantine protocols. Things like this are typically more complex than they seem at first glance, which is one reason to do a dry-run, despite having spent a lot of time developing the protocols and talking through the entire procedure.
How did it go? Pretty well, overall. Merlin’s a pretty good practice-patient since he’s easy to handle. However, the trial run got us thinking about a few things we hadn't considered, helped identify some little points to improve, and gave us good practice with donning and doffing (i.e. putting on and taking off) personal protective equipment (PPE, one of the most complex and easy-to-screw-up aspects of high-risk patient management).
What are the odds we’ll ever do this for real? Very low. However, it we ever have to, we’ll be very glad we tried it in advance.
With regard to what we’re doing for animals (like this training exercise) and the broader Ebola-management training in human healthcare, one question I've been asked a lot is "Isn’t this a complete waste of time and effort?" It’s very unlikely that the overwhelming majority of healthcare centres in Ontario will encounter a case or Ebola, just like it’s very unlikely we’ll have to manage a potentially exposed pet. However, the time spent isn’t a waste. While Ebola may not make it here, we will continue to encounter emerging diseases. All this training, along with the communication networks and similar behind-the-scenes work that’s going on will better equip us for the next infectious disease challenge. We may not know what’s coming, but the main aspects of response to a lot of infectious diseases are the same.
How’d Merlin do? He didn’t really appreciate waiting around in the crate outside in the cold while we were donning and doffing PPE, and getting ourselves sorted out, but lots of treats were involved so he didn’t seem to mind too much.
Photos: A, B Loading Merlin into a crate and covering it for transport; C Merlin (in his crate) in the back of the transport truck; D Two response team members in full PPE at the quarantine site.
The Public Health Agency of Canada (PHAC) has released the 2012/2013 Human Antimicrobial Drug Use Report.
Why write about this on a site dedicated to zoonotic diseases and diseases of animals? For a few different reasons, actually. One is that we have to realize that antibiotics (and bacteria) don’t care if drugs are used on animals or people, just that they are used. Antimicrobial use in any species can select for resistance, and some of those resistant bugs like to move between species. Therefore, antibiotic use in animals can lead to problems in humans, and (while often ignored), antibiotic use in humans can lead to problems in animals.
The PHAC report is a big document (with lots of pretty graphs) and I can’t do it justice in a couple of paragraphs, so if you’re interested in this area, take a look at it yourself via the link above. Here are some highlights from the executive summary:
- In 2013, office-based physicians saw patients for more than 293 million diagnoses, resulting in 23.8 million antimicrobial recommendations (8% of all diagnoses).
- A total of 22.8 million antimicrobial prescriptions were dispensed through pharmacies representing 202,000 kilograms of active ingredient.
- Pneumonia and acute sinusitis had the highest percentage of all diagnoses resulting with an antimicrobial recommendation (85% and 84%, respectively).
- Children between the ages of 3 and 9 years had the highest percentage of diagnoses with an antimicrobial recommendation, consisting mostly of penicillins or macrolides.
- Overall levels of prescriptions and costs associated with antimicrobials dispensed through community pharmacies have decreased consistently since 2011.
- Although the most commonly prescribed antimicrobials for 2013 were amoxicillin, ciprofloxacin and azithromycin, prescription rates for nitrofurantoin, moxifloxacin and azithromycin have shown dramatic changes between 2000 and 2013.
- Overall prescription rates for oral antimicrobials have not shown dramatic changes between 2010 and 2013 while increases have been seen in the volume of parenteral [injectable] products dispensed through outpatient pharmacies. However, the volume of antimicrobials for parenteral administration remained low relative to the volume of oral products; in 2013 there were more than 260 oral prescriptions dispensed for each parenteral antimicrobial prescription at the national level.
- In 2013, antimicrobial use was highest among the youngest (0-5 years) and oldest (65+) age groups with the youngest (0 to 5 years) group having observed the greatest prescription rate decline between 2010 and 2013. However, in 2013, levels of use in children between 0 and 5 years was 30% (230 prescriptions/1,000 inhabitants) more than what was observed in the general population (872 compared to 642 prescriptions/1,000 inhabitant).
- Regional differences were observed in the diagnoses and antimicrobial recommendation rates, as well as overall levels of use and cost associated with antimicrobial prescriptions. The province of Newfoundland and Labrador displayed the highest levels of use for all measures, with use 30% higher than that reported for the second highest province (Saskatchewan).
- Looking at specific antimicrobials, Newfoundland and Labrador had the lowest levels of use for vancomycin, while Québec had the highest use for cefadroxil, cefprozil, ertapenem, minocycline, moxifloxacin, penicillin v and vancomycin.
- The total mass of active ingredient purchased by hospitals was highest in Manitoba and lowest in Québec, while the cost was lowest in Ontario and highest in British Columbia. The higher levels of purchased antimicrobials in Manitoba was due to ceftriaxone purchasing.
So, where are the corresponding use data for animals? Unfortunately, for the most part in Canada, they don’t exist. Tracking of overall antibiotic use in animals is poor and that hampers efforts to improve use and better understand the relationship between use and resistance. Being able to effectively and accurately track antibiotic use (and resistance) in both humans and animals is critical, but lacking.
The cats were mainly indoor cats owned by one person - a pretty classical case of cat hoarding. All were in very poor condition. There were vaccination records for 15 of them, but there was no way to figure out which record corresponded to which cat (e.g. "black cat" doesn’t help much when you have 30 black cats in the group).
Since all of the cats had to be considered unvaccinated and they were exposed to a rabid animal, that left two options: euthanasia or 6 month quarantine. The logistics and cost of a 6 month quarantine, along with the poor condition of the cats themselves (and probably concerns about finding adequate homes after quarantine) led to the decision to euthanize the group.
Sometimes, these decisions have to be made despite knowing that the true risk of rabies exposure was very low. However, that’s not the case here. There was one confirmed rabid kitten, but other kittens in the litter had already died by the time that one was tested. The others may have also had rabies. The kittens had to get rabies from something, and if they were indoor (which is probably the case here given the primarily indoor nature of this group and their age), that means the virus probably came from one of the indoor-outdoor cats or from the mother (no word on her health status), which means there were multiple potential sources of exposure for the larger group than the one kitten that tested positive.
In some ways, they got lucky here. The kitten was taken to a veterinary clinic, where it bit a technician. The clinic fortunately did things right and reported the bite, and the kitten was tested. Otherwise, this would not have been picked up and there’s a much greater chance that the owner or someone else would have been exposed, and possibly died.
Inadequate rabies vaccination of this group led to the deaths of 50 cats, expensive post-exposure treatment of a few people (the veterinary technician, an animal control officer who was also bitten, and likely the owner), and presumably a lot of time and effort investigating this.
This case, and other recent rabies diagnoses, is plotted on wormsandgermsmap.com
More information about rabies is also available on the Worms & Germs Resources - Pets page.
It’s that time of year. No, not for snow (although it is snowing here at the moment). It’s time for the annual US rabies surveillance report in the Journal of the American Veterinary Medical Association (Dyer et al. Rabies surveillance in the United States during 2013).
- Over 5800 rabid animals were identified in the US. 92% of those were wildlife. That’s going to be a profound underestimation since most rabid wildlife aren’t caught and tested, but it shows that rabies is still alive and well in the US.
- Rabies was most commonly diagnosed in raccoons, followed by bats, skunks and foxes.
- Among domestic animals, there were 247 cats, 89 dogs, 86 cattle, 31 horses/mules, 9 sheep/goats, 3 pigs, 2 llamas, and a partridge in a pear tree. (Obviously the last one’s my lame attempt at early winter humour. Birds aren’t a rabies concern).
- Other species affected included mongooses (38; as always, just from Puerto Rico), groundhogs (37), bobcats (16), coyotes (5), deer (5), otters (3), opossums (2), wolves (2), marmots (2), a rabbit and a fisher. Most of those are fairly typical, both in terms of the species affected and the numbers.
- Pennsylvania had the most rabid cats, while Texas won for most rabid dogs.
- Vaccination history was not usually available for rabid dogs and cats. None of the rabid cats had been properly vaccinated against rabies. One of the rabid dogs had been vaccinated, a 10-month-old dog that developed rabies 7 months after receiving its first dose. This one’s a bit concerning, though. By being vaccinated at 3 months of age, it would have been considered "up-to-date" on rabies vaccination and this would therefore be a vaccine failure. No vaccine is 100% effective (although rabies vaccine is considered very effective as vaccines go) and the dog having only received only one dose because of its age was probably a key factor.
- The dominant rabies virus variants had a typical geographic distribution (see map above).
Three people were diagnosed with rabies during the year.
- The first was a person who died of raccoon rabies. There was no history of animal exposure, but he had received a kidney transplant 17 months earlier. The donor had been diagnosed with severe gastroenteritis, but also had some neurological abnormalities and when banked samples from the donor were tested, rabies virus was found. Three other organ recipients were then given post-exposure prophylaxis.
- The second person was a man from Guatemala who was detained trying to enter the US. While in custody, he developed neurological disease and died. Central American canine rabies variant was identified.
- I assume the third reported case was the organ donor from the first case, since the case was diagnosed in 2013 (even though the person died in a different year).
As per usual, there’s a little information about Canada and Mexico in the paper.
- 116 rabid animals were identified in Canada, 88% of those being wildlife. There were also 12 cats and dogs (combined) and 2 horses.
- In Mexico, an important finding was the fact that, for the first time since 1938, no people died of rabies. Eleven rabid dogs were identified. However, care must be taken in comparing data from different countries because of potential differences in testing (if you don’t look too hard, you don’t find).
Today, guidance documents coordinated by the US Centers for Disease Control and Prevention and the American Veterinary Medical Association were released. CDC descriptions of the two documents are below. Click on the title to get the document.
This document provides interim guidance based on the latest scientific evidence and recommendations from national organizations, for the management of pets, specifically dogs and cats, owned by Ebola virus disease (Ebola) contacts.
Interim Guidance for Dog or Cat Quarantine after Exposure to a Human with Confirmed Ebola Virus Disease
The intent of this interim guidance is to provide guidance for companion animals, specifically dogs and cats with exposure to a person with Ebola, based on the latest scientific evidence and recommendations from national organizations. This interim guidance describes the process for conducting a risk assessment for exposure of dogs or cats that had contact with a human with laboratory-confirmed evidence of Ebola, and it describes how to implement quarantine of dogs or cats if deemed appropriate by state and federal human and animal health officials.
Image: Scanning electron micrograph of Ebola virus particles budding from a cell. (Source: CDC Public Health Image Library #17775)