Clean hands, a New Year's Resolution
I've never been one to make New Year's resolutions. I figure if it's important and something I should do, why wait until January 1 to start? However, New Year's resolutions can be a good way to get people thinking about ways to improve their health. NovaNewsNow.com has a good idea for a practical and useful resolution: better hand hygiene. The article contains some good tips on when hand hygiene is needed. Hand hygiene is the term used for hand washing or use of alcohol-based hand sanitizers, and hand hygiene is one of the most (if not the most) effective and important infection control tools in hospitals, and in the community. Despite this, most people don't perform hand hygiene often enough (or properly), resulting in unnecessary risks of disease transmission.
Have a Happy New Year, and clean your hands.
Dog Bite Septicemia - Capnocytophaga canimorsus
Lots of people have heard of cat scratch fever (an infection caused by Bartonella henselae, which is often transmitted by cat scratches and bites), but dog bite septicemia is a much less familiar condition, although it is equally if not more serious when it occurs. As the name suggests, the infection (caused by the bacterium Capnocytophaga canimorsus) is typically transmitted by dog bites, and causes an infection of the bloodstream, resulting in very serious body-wide illness. The bacteria can also cause other types of infection including meningitis, endocarditis (infection of the heart valves) and rarely ocular infections.
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One study reported that 16% of dogs carried C. canimorsus as part of the normal bacteria in their mouths. Compared to the number of dog bites that occur, C. canimorsus infection is relatively uncommon. Most of the people affected by this bacteria have some kind of predisposing factor, particularly having had their spleen removed (splenectomy), having a weakened immune system, or being an alcoholic. The majority of cases occur in people who have regular close contact with dogs or who were bitten by a dog. Septicemia with C. canimorsus is fatal in approximately 1/3 of cases.
Prompt attention and treatment of dog bites is the best defence against bite-associated infections, including C. canimorsus. The bacteria are typically susceptible to many different antibiotics, but if treatment is delayed too long, the damage to the body may be too severe for the patient to survive.
ALL bite wounds should be taken seriously, and immediately washed thoroughly with lots of soap and water. Consult a physician for any bite on the hand, over a joint or tendon sheath (such as on the wrist or ankle), over any kind of implant or prosthesis, or in the groin area. It is also very important to consult a physician regarding treatment of any bite to a person with a compromised immune system, who has had their spleen removed, or who has any serious underlying chronic disease. Animal bites should also be reported to the local public health department.
More information on bites, much of which is also applicable to dog bites, is available on the Worms & Germs Resources page on the cat bites information sheet.
Picture: Trained attack dog Samo leaps forward toward a decoy's arm wrap as Tech. Sgt. David Adcox restrains him. (USAF Photo archives)
Pet vaccine risks
Life is not risk-free. We shouldn't stop doing beneficial things just because of potential (and rare) side-effects, particularly when the benefits in most cases far outweigh the risks.
A recent article in the Cleveland Examiner discussed feline distemper (panleukopenia) vaccination. The author related the story of a cat that apparently had a "bad" (undescribed) reaction to the vaccine, which is certainly possible. Adverse reactions to vaccines are rare, but they certainly can (and do) occur. It's important that we don't react excessively to these highly unfortunate reactions, and end up in a situation where more animals get sick and die from the disease because people get scared of vaccinating against it. (The increasing rates of measles in people in some areas, including serious outcomes, following ill-informed paranoia of an association between vaccination and autism is a great human example of that).
The author goes on to state:
"What should you do to guard your cat against feline distemper? Ask a holistic practitioner for nosodes instead of a vaccine serum." But there is no evidence whatsover that nosodes have any effect. A cat "vaccinated" with a nosode is an unvaccinated cat.
"The diluted formula is safe—it contains no live pathogens-- and effective." It's probably safe, but in no way effective.
"A cat who doesn’t mingle with other animals probably doesn’t need a vaccine against viruses." Bad advice. You'd be amazed by the number of 'indoor cats' that are taken to vet clinics after being hit by a car, getting in a fight with a stray cat, or similar non-indoor encounters. Close contact with strays can also occur through screen doors and windows. Then there's the issue of rabies exposure from bats in houses. Altogether, avoiding vaccination of indoor cats will probably get the majority of cats in more trouble, not less!
Bathing iguanas - Good ideas done in a bad way
A recent report in the Daily Gleaner discusses the book Iguanas for Dummies. In this book, the author recommends frequent bathing of iguanas because they normally soak in the wild. Bathing iguanas in the tub is also recommended on various websites. Letting iguanas soak in water is a good recommendation for their health, but there are good ways to do this and bad ways to do this. Soaking them in a bathtub (or sink) is a bad idea.
The Daily Gleaner article points out that bathing iguanas in bathtubs when there are children or immunocompromised people in the house is a bad idea, and that a separate bathtub should be used. I'm glad to see the risks of infectious disease to immunocompromised people are considered, however I'd take it a step further.
- Reptiles are high risk pets in terms of Salmonella infection. There is a disproportionate rate of Salmonella infections in people that have contact with reptiles, not just immunocompromised people. Fatal infections are rare, but do occur. People that own reptiles need to be aware of this and take practical measures to reduce these risks.
- Iguanas should never be bathed in the bathtub, regardless who lives in the house.
- Iguana cages should be of adequate size and design so that they can soak in their own enclosure. Otherwise, a container (e.g. a large plastic storage bin) that is only used for bathing the iguana should be used. Waste water should not be dumped in kitchen or bathroom sinks. The container should be disinfected regularly. Hands should be washed immediately after handling the iguana, the container or the waste water.
- Households with immunocompromised people or young children should probably not have iguanas.
More information that is applicable to iguanas can be found in the Turtle information sheets on the Womrs & Germs Resources page. There are also sheets with more information on Salmonella.
Infection control for small animal veterinary clinics
Infection prevention and control is a critical component of good medicine, human or veterinary. However, veterinary infection control is a very small and underdeveloped field, and good resources for veterinary personnel are limited. To help advance this important field, a comprehensive infection control document entitled "Infection Prevention and Control Best Practices for Small Animal Veterinary Clinics" has been developed by the crew at WormsAndGermsBlog and colleagues at the Ontario Veterinary College. This document is a comprehensive overview of infection control practices and has been designed as a resource for all small animal veterinary clinics. The document can be downloaded by clicking here or through the Worms & Germs Resources page.
This effort was sponsored by the Canadian Committee on Antibiotic Resistance and the guidelines have been endorsed by the Canadian Veterinary Medical Association and University of Guelph Centre for Public Health and Zoonoses.
Strep throat - Don't blame your dog!
My wife has a lousy immune system. She's a good indicator of whatever infectious diseases are circulating in the region. After running through a stretch where our whole family was biohazardous (baby with a cold, older two with two different bugs that they then spread to each other), Heather developed strep throat. This common bacterial disease is caused by Group A Streptococcus. I've previously posted about issues regarding strep throat and pets, and the fact that there is little evidence supporting pets as sources of strep throat in households. However, I still get asked about this, and I still see recommendations on the internet to test or even treat pets to try to contain strep throat in a household (for example, see these posts on medhelp.org and justanswer.com).
As a veterinary infectious disease specialist who runs a microbiology research lab (and someone who likes to play around and look for strange things), I'm in a perfect position to start culturing my pets to look for a link, but I don't bother. We've not found any convincing evidence, and neither have other groups, that pets are a source of strep throat for humans. There are a number of zoonotic disease concerns involving household pets, many of which dont' receive adequate attention, but this isn't one of them. More information about "Pets and Strep Throat" can be found in the previous Worms & Germs post of the same name.
Cheyletiella - The walking dandruff
Cheyletiella is a genus of mites that commonly affect dogs (C. yasguri), cats (C. blakei), rabbits (C. parasitovorax), and occasionally people. Unlike Sarcoptes species (the mites that cause sarcoptic mange), these mites live on the surface of the skin and do not burrow into deeper layers. They feed on dead skin cells and occasionally tissue fluid. Infestation with these mites can be very itchy, but not always. Cats in particular can carry the mites without any visible abnormalities of their skin or fur. Typically, however, the affected animal's fur becomes crusty, scaly and inflamed, and sometimes patches of fur may be lost. The mites are usually a little less than a half-millimetre long (so they are visible to the naked eye if you look closely) and grayish-white. They tend to be quite active and crawl around (but they don't jump like fleas), which gives them the appearance of walking dandruff. Diagnosis is easy if the mites are seen strolling around on a table or blanket, otherwise they may be found on a "scotch tape test" or superficial skin scraping.
People can be affected too if they have close contact with a pet carrying Cheyletiella. Lesions, which usually take the form of single or grouped small red bumps on the skin, typically appear on the arms, trunk or thighs, and sometimes can be extremely itchy! It is rare to see the mites themselves on a person - usually they're found on the pet. The good news is these mites can't actually complete their life cycle or survive for long on people, and in the environment even the hardiest forms of the parasite (usually the eggs and adult females) die within about ten days. So once the source of the mites is eliminated (by treating the pet with an appropriate anti-parasitic drug which your vet can prescribe), the signs in any affected people will resolve on their own without specific treatment (but you might want something for the itch!).
Photo: Light micrograph of C. yasguri from a dog (credit: Dr. M. Dryden, College of Veterinary Medicine, Kansas State University)
Tritrichomonas fetus in cats
I had an advice call the other day about control of Tritrichomonas fetus in cats. This protozoal parasite is being recognized as an important cause of diarrhea in cats, particularly in crowded situations such as catteries. In addition to the standard discussion about control of this parasite in cats, the question about human risks was raised. Tritrichomonas fetus is passed in the stool of infected cats, and other cats become infected by ingesting the organism. It is certainly possible that someone with an infected cat could be exposed to this parasite through inadvertent ingestion of the parasite following contact with infected surfaces (e.g. the cat's fur or litter box). Although this sounds gross, it probably occurs more often that we think. We encounter bacteria of fecal-origin regularly throughout the day. Keep that in mind the next time you don't want to be bothered washing your hands.
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The risk of human infection with T. fetus is unclear, but is probably quite low. There is only one report of human infection by this parasite, and the person was immunosuppressed. Risks to healthy people are probably very low but we can't say there is no risk. Basic hygiene measures (especially hand hygiene and good litter box management) should reduce the risks even further. People with weakened immune systems should take greater care (because of the risks from this organism and many others), but still, common sense practices are the key. More information about household infection control and litter box management for cat owners is available on the Worms & Germs Resources page.
Some excellent information on Tritrichomonas fetus can be found on the website of Dr. Jody Gookin, a leading researcher in this field.
Rabies Vaccination in Horses: Core Issues
In 2008, the American Association of Equine Practitioners (AAEP) published updated vaccination guidelines for horses. One of the changes from the previous set of guidelines was the inclusion of rabies as a core vaccine (meaning every horse should receive it). There was lots of discussion about this at the recent AAEP Annual Convention in San Diego, CA.
Some veterinarians don't like the idea of vaccinating every horse against rabies. Just like veterinarians and owners of dogs and cats who are concerned about over-vaccination in these species, the same concerns exist in equine medicine. Equine rabies vaccines are not approved for use every three years like some canine and feline vaccines, so they still need to be given every year until someone can determine for how long a vaccinated horse is protected from infection. Furthermore, there has never been (to my knowledge) a case of human rabies due to transmission from a horse. These are all valid points, but there are also a lot of reasons why including rabies as a core vaccine for horses is very good idea:
- Rabies is a very deadly disease, in both animals and people. To some owners, their horse is every bit a part of their family as any dog or cat could be. To other owners, their horses represent a great investment, and part of their livelihood. Even if the risk of disease in horses is low, protecting them is safe and easy, so it just makes sense. As the saying goes, an ounce of prevention is worth a pound of cure, but when there is no cure and prevention is so simple... you do the math.
- Rabies vaccination is extremely effective in horses, producing an excellent immune response even with a single dose. It does not require complex adjuvants that some other vaccines need to stimulate the immune system, which also makes it less likely to cause an abnormal vaccine reaction.
- Rabies is not a seasonal disease like many of the respiratory viruses or insect-borne diseases (e.g. West Nile) for which horses are also typically vaccinated. Rabies boosters only need to be given once a year, so this can be done during a time of year when no other vaccines are required, if there are concerns about giving too many vaccines at once.
- Horses live outside and in barns. Most are far less supervised than dogs and cats, but even these animals are at risk of rabies exposure. A rabid animal could easily be "brave" enough to attack a horse, even though it normally wouldn't. Bats can also easily get into and out of many barns - you may never know one was there, and finding a bite mark from a bat on a horse would be like looking for a needle in a haystack, but that's all it takes to transmit the virus. So it makes sense to give your horse added protection by vaccinating it.
- Rabies in horses may not look like rabies at first. One of the most common early signs is actually colic. A rabid horse that looks like a colic may expose the people who are trying to look after it before they realize what the horse has. In other horses the signs may be recognized too late, like the rabid horse that was found at the Missouri State Fair earlier this year, that resulted in exposure of many people.
- While rabies transmission from horses to people has not been documented, rabid horses have killed people, particularly horses that develop the "furious" form of rabies, which can cause them to become very violent.
For more information on rabies, see our rabies archive or the information sheets available on the Worms & Germs Resources page. For more information on rabies in horses specifically, visit our sister site, www.equIDblog.com.
My dog has an MRSI infection, should I be worried?
Infections caused by methicillin-resistant staphylococci are an increasing problem in veterinary medicine. Staphylococci are a group of bacteria that can cause various infections in many different animal species, including people. The one that gets the most attention is methicillin-resistant Staphylococcus aureus (MRSA). There is more information about MRSA in animals on the Worms & Germs Resources page and in our MRSA archives.
While MRSA gets most press, infections by methicillin-resistant Staphylococcus pseudintermedius (MRSP) are more common in dogs. (More information about the issues with naming staphylococci (particularly MRSI vs MRSP) can be found in the post "Methicillin-resistant Staph: What's in a name?"). These canine MRSP infections creat many frustrating and concerning situations. They can be very difficult to treat because they are resistant to a large number of antibiotics. However, with the proper testing we can usually identify an effective antibiotic to treat these infections, and the prognosis for dogs with MRSP infections is usually good, unless they have a very severe or invasive infection.
I get advice calls about management of MRSP on almost a daily basis. The first question is usually what treatment should be used. Almost inevitably, the second question is about human health concerns, because of the awareness of MRSA in people. MRSA can be transmitted from pets to people, although it probably more often goes from people to pets. MRSP can also be found in people, but it is very rarely identified as a cause of disease in humans. Someone in contact with an infected dog is probably more likely to carry MRSP in their nose, but they are unlikely to develop an MRSP infection. However "unlikely" doesn't make it impossible.
If someone has a dog with an MRSP infection, it's important to know that this is different than MRSA. The risks of human infection are likely much lower. Nonetheless, the last thing you want is an infection with a multidrug-resistant bacterium, so some basic measures should be employed to reduce the risks:.
- Avoid direct contact with the infected site(s). If you have to touch infected site (e.g. when applying ointment or changing a bandage), wear disposable gloves and always wash your hands well when you take the gloves off.
- Keep infected sites covered with a bandage if possible.
- Wash your hands or use an alcohol-based hand sanitizer regularly after contact with the dog, and always after contact with the infected site (even if gloves were worn) or the dog's nose or hind end. Remember that MRSP can be carried in the dog's nasal passages and intestinal tract.
- Avoid contact with the dog's stool.
- People with weakened immune systems, very young children and elderly individuals are probably at higher risk for infections, and should therefore avoid contact with infected dogs whenever possible.
- Don't let infected dogs sleep on the bed or on other areas where people have close and frequent contact (e.g. couch).
- While the risks are low, if you have any concerns, talk to your physician.
Blastomycosis and dog bites
I just received this comment from a reader of an earlier post about blastomycosis:
What should be done if a person was bit by a dog with blasto? I was trying to pill a dog who has blasto and the dog just out of reflex shut her mouth on my finger. What are the chances of the blasto being transmitted to me?
It's a reasonable question and one that I get periodically. If the bite didn't break the skin, the risk is essential nil. If the bite broke the skin, the risk is still fairly low, but certainly not zero.
Simple contact with an infected dog cannot result in transmission of blastomycosis because Blastomyces is a dimorphic fungus, meaning it can take the form of either a mold or a yeast. The highly infectious mold form is found in soil at ambient temperatures, while the minimally transmissible yeast form is present in the body of an infected animal or person. However, bites can be a different story. A bite from a dog with advanced pulmonary blastomycosis (e.g. fungal pneumonia due to Blastomyces) can result in localized blastomycosis at the site of the bite (e.g. only the person's finger might get infected).
Considering the dog in this case was already being treated for the infection (and therefore hopefully was not shedding much of the fungus), and that there are very few reports of bite-associated blastomycosis, the risk is probably quite low. However, any bite that breaks the skin can result in infection from the multitude of bacteria in an animal's mouth. Any bite on the hand should be taken seriously because it's easy for sensitive structures like joints and tendon sheaths to become infected. Consulting your physician or getting medical attention is recommended.
More details about general issues regarding animal bites are available in our bites archives. Relevant information is also available in the Cat Bites information sheet on the Worms & Germs Resources page.
Photo: Light micrograph of the budding yeast form of a fungus.
Human rabies with long incubation time
Rabies is very unique virus in many ways. One unusual aspect of rabies is the amount of time that can elapse between exposure and development of clinical disease (illness). This is called the incubation period of virus. Usually people develop rabies within six months of exposure (e.g. from a bite from an infected animal like a dog or a bat). However, longer incubation periods can occur.
Some rabies cases with purportedly long incubation periods can't be confirmed because the person may have been exposed to the virus multiple times. In countries where rabies virus is not present, it is much easier to tell when a person is exposed because they had to have been traveling abroad. Such a case was reported in the December 2008 edition of the journal Emerging Infectious Diseases. The case described was that of a ten-year-old girl that died of rabies in Australia, a country which is rabies-free. The child had lived in Australia for five years, but previously lived in Vietnam and Hong Kong, where rabies is common. Since she had not left Australia in the last five years, it is almost certain that she was exposed to the virus at least five years before developing disease.
One potential complicating factor in some rabies-free countries is the presence of one or several bat lyssaviruses, which are very closely related to the rabies virus (in fact, the rabies virus itself belongs to the Lyssavirus genus). These viruses can also cause disease that looks very similar to rabies. Human cases of infection by bat lyssavirus were reported in Australia after the child in the report died of rabies, but analysis of viral RNA collected from the girl recently confirmed that it was rabies, and not another lyssavirus. Also, typing of the rabies virus showed that it was most consistent with a Chinese strain, which suggests that she acquired the infection in Hong Kong. This demonstrates that rabies can have a very long incubation period.
Rabies is a devastating disease but one that is largely preventable in people, given proper attention and access to post-expsoure treatment. More information about rabies can be found in on the Worms & Germs Resources page and in our rabies archives.
Photo: Electron micrograph of a rabies virus (source: Tektoff-RM/CNRI/Science Source/Photo Researchers, Inc.).
Human rabies in Missouri
A 55-year-old man in Missouri recently died of rabies. He was the first human rabies victim in that state in close to 50 years. He was apparently bitten by a bat in mid-October and started to show signs of rabies about six months later.
This tragic incident highlights a few important points. All bats should be considered rabid until proven otherwise. Any bite from a bat should be considered rabies exposure. If this person had received treatment for rabies exposure, he almost certainly would not have developed rabies. Post-exposure treatment consists of a dose of antibodies against the rabies virus as well as a series of 5 vaccinations over four weeks. These are normal vaccines given in the arm - not like the old horror stories of reaction-prone vaccines given in the abdomen.
- Treat every bat as rabid. If you are bitten or may have been bitten (i.e. you were asleep in a room with a bat), you should consider yourself exposed unless the bat is tested and shown to be negative.
- If you are exposed to rabies, get proper treatment. It's not a big deal and it can save your life. See this post for my experience with bat rabies.
- Dogs and cats must be vaccinated against rabies. Even if they don't go outside they can still be exposed. It's also the law in most areas.
- Bat-proof your house. Seal up holes and crevices where bats may hide or through which they may get into your home.
- If you wake up in a room and see a bat, don't let it out. It must be caught and tested for rabies, or you should receive post-exposure treatment. Bats can bite sleeping people without them noticing.
- Wildlife should want to stay away from people. Wild animals that are acting strangely or do not appear afraid of people could be rabid. Stay away from such animals and report them to your local animal-control official.
More information about rabies can be found on the Worms & Germs Resources page, and in our rabies archives.
Neurological bunnies: Encephalitozoon cuniculi
Encephalitozoon spp. are single-celled microsporidian parasites that can cause infection in the intestinal tract of animals and people, and sometimes infection in other parts of the body (systemic infection). Cases of infection with these parasites (encephalitozoonosis) have been reported in countries all over the world. The species E. bieneusi and E. intestinalis are the most common. A much less common species, E. cuniculi, is thought to be one of the most virulent microsporidia that infects humans (i.e. it causes the most severe infections). Encephalitozoonosis is rare in healthy people, but it is a common complication in patients with weakened immune systems. Encephalitozoon cuniculi can also be found in many animal species, particularly in rabbits. Most infections in rabbits do not cause illness (i.e. subclinical infections), but when disease occurs it typically causes neurological signs. In these cases the parasite tends to attack the brain and kidneys. The primary means of transmission between rabbits is E. cuniculi spores shed in the urine. Organ damage in the few human cases that have been reported have also been primarily in the brain and kidneys.
Direct transmission of this parasite from rabbits to humans has not been reported, but because there is also no evidence that it can't be transmitted from rabbits, the disease is so severe when it does occur, and the parasite is so common in rabbits, it is still prudent to take a few simple precautions. This includes washing your hands after handling rabbits, and keeping rabbits away from food preparation areas and food meant for human consumption. Anyone with a weakened immune system should be particularly careful, and ideally should have someone else clean out their rabbit's enclosure on a regular basis.
In general, the risk of illness in a rabbit and zoonotic transmission can be reduced by proper handling, good management, personal hygiene and routine healthcare. A rabbit that is not stressed and is well cared for is less likely to be susceptible to infection, and therefore less likely to transmit infection to a person. More information about rabbits is available on the Worms & Germs Resources page.
Electrolyzed water: manipulating science for profit
People are increasingly concerned about exposure to infectious agents, both for themselves and their pets. This has led to marketing of various products to reduce the risk of disease transmission. Some are good, some might be useful but are unproven, and some are just horrible. Many in this last category manipulate scientific data to try to convince people that their product is useful. I ran into one of those today while I was reading an article that recommended the use of electrolyzed water to protect pets from Salmonella.
Electrolyzed water is a weak electrolyte solution (such as tap water) that has had an electric current applied to it. The electric current acts on salt in the water and forms a weak acid and oxidizing agent (i.e. a weak disinfectant). It has been shown that electrolyzed water can be useful for disinfection of surfaces in food-handling areas, for reducing bacterial numbers when sprayed on carcasses in slaughterhouses, and possibly for treatment of contaminated food. The effect of spraying electrolyzed water on final food products, like pet food (raw or commercial) is unclear.
The science behind electrolyzed water has been used by some companies as an excuse to sell expensive electrolyzed water products for pets (and people) to drink. There is no evidence that drinking electrolyzed water helps reduce disease. Really, why would you want to drink a disinfectant, regardless of how "natural" it is? Bleach (at the right concentration) can kill Salmonella, but that certainly doesn't mean that drinking a weak form of bleach is good for you.
It's likely the biggest thing you have to lose with products like this is money, but make sure you don't use unproven (or illogical) products in place of basic, common sense measures to reduce the risks of disease. If you are considering buying products to promote the health of your pets or yourself, do some research and try to find as much objective, independent information as possible. Don't rely on company information and testimonials. Here's an example of one company's website that sells electrolyzed water. This page is about the human product but their pet version is the same. My general rule is that anything that purportedly cures all that ails you probably cures nothing.
P.S: This same company's site contained one of the funniest false quotes that I've seen in a while. The site states that "The New England Journal of Medicine reports that more than 80-90% of canine skin and other problems are caused by toxins in a dog's body." The New England Journal of Medicine is a world-renowned journal of human medicine, which certainly has better things to do than report false science about dogs (or anything about dogs for that matter!).
