Rabies quarantine

There are two situations when animals may be quarantined because of rabies concerns:

  1. After biting a person.
  2. After potentially being exposed to a rabid animal.

The time frame for quarantine in these two situations is quite different because of what the quarantine is meant to accomplish.

Animals that have bitten someone are quarantined for 10 days under observation to see if they develop signs of rabies. Most animals that bite do not have rabies, and this is the easiest way of determining whether the animal could have potentially transmitted rabies by way of the bite. If an animal was rabid and infectious at the time of biting, it would die from the disease within 10 days. Animals can only transmit rabies virus after it has reached the brain and started to spread outwards via nerves - it gets into saliva by working its way down nerves from the brain to the salivary glands. Once an animal gets to that stage of disease, they die quickly. So, if the animal is still alive after 10 days, it was not rabid at the time of the bite. Quarantine is important so that it can be clearly proven one way or the other whether the animal was rabid. If the biting animal was not quarantined and ran away, the recommendation would be to err on the side of caution and treat anyone bitten as if they'd been exposed... but we want to avoid that if at all possible.

The second type of quarantine (for a potentially exposed animal) is based on less solid evidence. The idea in these cases is to keep the potentially exposed animal isolated while waiting to see if it develops signs of rabies, because there is no other reliable test for rabies in a live animal. For example, if an unvaccinated dog gets into a fight with a rabid raccoon, it would be considered potentially exposed. It would be quarantined (or immediately euthanized... the other option) and monitored to see if it develops signs of rabies. The length of quarantine for non-vaccinated dogs is usually 6 months, but this may vary by region. This helps reduce further rabies transmission by ensuring that a dog that develops rabies during the quarantine period is not roaming at large and able to infect people or other animals. One weakness of this approach is the incubation period of rabies, which can be very long. There is not a lot of objective research on which to base the 6 month time frame (unlike the 10 day quarantine described above). After 6 months, it's very unlikely the dog will develop rabies, but we can never say it's 100% because of the rare cases of rabies in humans with extremely long incubation periods. In reality, it's likely that the vast majority of animals that are exposed will develop rabies before 6 months, so it's a reasonable time frame. Would it be better to use 4 or 8 months, or something else? Possibly, we just don't know.

The easiest ways to avoid hassles associated with rabies quarantine are:

  • Prevent bites. If your pet is trained and observed properly, it's unlikely to bite anyone, so the 10-day post-bite quarantine shouldn't be an issue.
  • Vaccinate your pet. Properly vaccinated pets are not subject to the same long, strict quarantine (although a shorter period of isolation (often at home) is usually still required).

More information about rabies can be found on the Worms & Germs Resources page.

Canine influenza vaccination

A canine influenza virus vaccine has recently been released. Canine influenzais a virus that originated from a horse influenza strain and is now circulating in some dog populations. (To my knowledge, we have yet to find it in Ontario. We didn't find any evidence of it in an earlier surveillance study). It typically causes mild disease, as with influenza in people, but can also cause serious (including fatal) infections. These cases are most common in densely-populated, stressful environments like shelters and racing greyhound facilities.

Like most vaccines, this canine influenza vaccine does not claim to provide 100% protection. Veterinary vaccines can get conditional licensing and be marketed with little evidence of effectiveness. The manufacturers have produced data "supporting product purity, product safety under normal conditions of use in field safety trials and demonstration that the product has a reasonable expectation of efficacy." That means they have shown the vaccine is produced with good practices, had no obvious adverse effects in a safety study, and there is a possibility that it could be effective (presumably from showing vaccinated dogs produce antibodies against canine influenza virus). During the conditional licensing period, the manufacturers "will continue to submit data obtained in support of the product’s performance, which will be evaluated by government regulators to determine whether a regular product license may be issued."

There's a good likelihood the vaccine will be effective at reducing the incidence and severity of disease, as with influenza vaccines in other species. Basically, if a vaccinated dog gets exposed to the virus, it should be less likely to get sick, and if it gets sick, it should be less likely to have severe signs. Reducing the incidence and severity of influenza also has the benefit of reducing the chances of developing a secondary bacterial infection, which can cause very serious disease.

Deciding whether to vaccinate your dog largely comes down to the risk of exposure and the implications of your dog becoming ill. In an otherwise healthy dog that is not in a high risk environment (e.g. kennel, shelter, greyhound racetrack), it's questionable whether vaccination is needed. If canine influenza virus is in the area, it's something to consider, but the virus seems to be rare (or at least rarely identified) in pets in most regions. Discussing the risks and benefits with your veterinarian is the key.

Canine influenza is NOT considered a zoonotic disease. There is no evidence that it can infect humans. Therefore, there is no public health argument for vaccination.

Image source: www.petinsurance.com/healthzone/pet-articles/pet-health/Canine-Influenza.aspx

Antibiotics: how about a dose of common sense

Antibiotic resistance is a major problem. Anyone that denies that is delusional. Anyone who thinks that antibiotic use in veterinary AND human medicine don't contribute to resistance are similarly clueless.

Most people do understand these basic facts. However, what people feel should be done about the problem is quite variable, ranging from doing nothing to proposing strict bans on antibiotic use. More legislators are proposing strong restrictions on antibiotic use in agriculture, but little gets mentioned about use in companion animals and humans. A broad approach looking at all sectors, involving all available evidence, and looking at the potential impact of restrictions is needed. Restrictions that have so may loopholes that they don't curtail overall use are not helpful, nor are restrictions that are so severe that they result in increased illness in animals (which could then require more antibiotics and/or public health risks because of more zoonotic infections). I certainly don't have the answers.  A concerted, broad-based effort is needed.

In an era where we have major concerns about antibiotic resistant bacteria and scrutiny of antibiotic use in veterinary and human medicine, it's completely ludicrous that you can walk into a farm supply store or pet shop in Canada and buy huge quantities of antibiotics, or order pretty much any antibiotic you want over the internet.  Politicians like to talk about antibiotic overuse and restricting drug use in animals, but fail to take the simple step of making NO antibiotics available without a prescription from a physician or veterinarian. That wouldn't solve all our problems, but would be a great start! One case from my time in private practice stands out - it was a steer (a castrated male cow) with a broken leg. The farmer noticed that the animal wasn't using the leg and tried treating it with penicillin for a few days, which didn't fix anything (surprise, surprise). This certainly isn't an uncommon event. Many people treat their animals (farm animals and pets) with antibiotics without any guidance, often for problems that are not bacterial infections, and sometimes using inadequate dosing regimens (which further increase the risk of microbial resistance). 

Taking the simple step of removing free access to antibiotics is easy and needs to be done. Controlling internet purchases is more difficult. One veterinary pharmacy website proudly states "We also have a wide variety of human grade antibiotics, none of which require a prescription!" This site has a wide selection of antibiotics for sale. Most are labeled for fish tank use, but the site mentions the human product names, and it's very clear these products are not really being sold for fish. These pharmacies are harder to control, but many are clearly located in countries like Canada and the US, and are blatantly breaking existing regulations. Take a look at the picture above... this human pharmacy is offering free Viagra, a prescription drug, with every order of levofloxacin, another prescription drug... all without a prescription from a physician. This isn't a matter of needing rules. It's a matter of simply enforcing them.

Antibiotic resistance is a complicated problem and simple measures aren't going to fix everything. However, if we don't even take simple steps, how are we ever going to take the bigger steps required to address this issue?

More on service animals and access

Recently, I wrote a commentary about the need to better define what service animals are because of potential abuse of regulations regarding service animals and the possibility that illegitimate use of the term could impact true service animals. Here are some good comments from a reader.

As a service dog user and trainer who sometimes lectures at the University of Guelph, I am sorry to see the American-centric slant to this article.  In Canada the guideliines are even more vague and there has to be a charter challenge to support the use of a service dog that has been owner trained.

  • The article was intended to discuss the American situation since I was talking about American legislation and responding to problems that people have asked me about in the US. Issues are different in various countries and the legal protections in the US certainly don't apply to Canada.
  • The last point raises some concerns. What constitutes "owner trained?" Service animals are highly trained to do their specific task and to work safely in public situations. I'm not convinced owner training makes a service animal. There needs to be at least some degree of supervision/review of the training and certification process.

I use a service dog to mitigate the effects of my invisible disability and the vagueness of the laws related to service dogs in Canada has made travelling and working with my dog difficult.  I get comments that range from "you don't look disabled" (which I usually reply to with -thank you!
neither do you!) to "that dog doesn't look like he is doing anything and how can he help you if he is asleep (believe it or not, he does get to sleep when I stop to work somewhere, but will wake up and work if needed).

  • Those are all legitimate concerns and I empathize with the problems you've had. That's why I think the "spirit" of the US's ADA is excellent. Protection needs to be in place for true service animals. Just as important is the need for education about what service animals are, what they do, and where they should be allowed to go. I also think this reader's concerns support my comments: We need to make sure that service animals are properly scrutinized. If people know that service animals are properly trained and regulated, they are less likely to have a problem with them. On the other hand, if people never know whether a service animal is really a service animal, then they may be less likely to give them the degree of respect and access they deserve.

I strongly feel that if you don't need a dog you won't take a dog with you; why would you? It is too much work!  For anyone who would like to take their pet with them to the grocery store, I would be delighted to take them with me to show them what travelling through the meat aisle is like; people stop and stare.  You have to plan your route so that the grocery clerk doesn't park their cart under my dog's nose (no...he won't touch it...but why make his day harder than it needs to be).  You need to be aware of the two year old who is covered in jam who wants to hug the doggy.    And you have to avoid hazards like the display of glass jars that tumbled and broke in front of my dog, surrounding him in glass shards with no way to safely walk out (stand stay! what a useful behaviour).

  • Sorry, but I disagree. I think that if a grocery store advertised that it was pet friendly, there would be dogs in there all the time. Some people bring their pets everywhere, no matter how much extra work it is.
  • Also, the grocery store example is a great one to highlight concerns. There are public health reasons why we don't want widespread animal access in grocery stores. Check out a previous post about a "service horse" walking through grocery store.

Life with a service dog is enriching for certain, but it is not something you want to do unless you need to.  I would advise anyone who is concerned about the illegitimate users to slow down, and think.  We are already protected.  If your dog is causing a problem, you can be asked to leave.

  • In Canada you can. In the US you can't. That was the point of the article. In the US, you can't ask someone to make an animal leave except under very specific circumstances that a true service animal should never create. What we need is more protection in Canada and more clarity in the US.

Image source: http://www.assistancedogsofthewest.org

Recommended changes in US rabies exposure protocol

Currently, people that have potentially been exposed to rabies undergo post-exposure treatment consisting of one dose of rabies antibodies followed by a series of 5 vaccinations on days 0, 3, 7, 14 and 28. It's not fun but it's much better than the old horror stories of 14 or more injections in the abdomen, which was the standard until the 1970s. For most people, the series of 5 rabies vaccines is not that big of a deal, but some people have adverse reactions, and having to undergo that many shots is not enjoyable, especially for children.

Now, a US advisory committee has recommended changing the vaccine requirements to 4 doses. There are a couple reasons for this. One is that many people end up skipping the final dose anyway and none have ever come down with rabies (although the strength of this argument is dependent on how many of them were truly exposed and at real risk of disease). Another is the cost of vaccination, which runs $100-200 per dose. When you multiply that by the tens of thousands of people that are treated annually, eliminating a single dose results in pretty big cost savings.

However, it's interesting that this recommendation has been made without coordinating with vaccine makers. Therefore, if this change is adopted, physicians would have to choose between following the US recommendations or the vaccine label. This could lead to confusion as well as legal liability concerns. "Off-label" drug use is a touchy area, and is generally frowned upon. Vaccine manufacturers may be unwilling to change the label because of a lack of scientific evidence clearly indicating that 4 doses are effective, plus the fact that it would instantly reduce sales by 20%. If this guideline is adopted, significant education efforts, assessment of liability and discussions with manufacturers will be needed. If 4 shots are truly effective (which is probably the case) this is probably a good change.

More information about rabies can be found on the Worms & Germs Resources page.

A need for a better definition of service animals

Because service animals are so important to the people they assit, they have much greater access to various venues than other animals. In the US, the Americans with Disabilities Act (ADA) specifically addresses service animal access issues. It was a landmark act that ensured appropriate access for these animals so that people who require them are able to take them into areas where other animals are not allowed. However, some aspects of this Act can lead to abuse of the regulations and unwanted scrutiny of "real" service animals. I was at an infection control conference recently and numerous people commented on problems they have had with people with questionable "alleged" service animals, the inability to find out whether they really are service animals, and the potential legal implications of trying to do anything to prevent them from entering certain areas.

These problems occur because of a combination of strong and vague statements in the ADA:

One problem is the definition of service animals: "Service animals are animals that are individually trained to perform tasks for people with disabilities such as guiding people who are blind, alerting people who are deaf, pulling wheelchairs, alerting and protecting a person who is having a seizure, or performing other species tasks."

  • The definition itself is fairly straightforward, but there is no clear indication of what "trained" entails, and no requirement for formal training or certification, nor restriction of any animal species. Based on this, I could say that my sheep are trained to do something for me and then take them into a restaurant with me.

Some other key points in the ADA:

Businesses may ask if an animal is a service animal or ask what tasks the animal has been trained to perform, but cannot require special ID cards for the animal or ask about the person's disability.

  • This means that while businesses can ask, all someone has to do is say "yes, this is a service animal" and the conversation is done. Some people that truly need service animals are not visibly disabled and you can't tell whether someone needs an animal by simply looking at them or talking to them. Back to my sheep example, if someone asked why I had a sheep on a leash in a restaurant, all I'd have to say if that he's my service sheep and he's trained to do something. Theoretically, I could walk into a crowded location with a Salmonella-spewing baby chick, adult cow or some other inappropriate animal and no one could do anything. Yes, those are extreme examples, but people like to test extremes.

A person with a disability cannot be asked to remove his service animal from the premises unless: (1) the animal is out of control and the animal's owner does not take effective action to control it (for example, a dog that barks repeatedly during a movie) or (2) the animal poses a direct threat to the health or safety of others.

  • The problem here is who defines "direct threat." This is an issue because it is subjective, yet people can be penalized if they ban an animal and a complaint is upheld. Think back to the recent example of the pet chimp that almost killed someone. It wasn't a service animal in this case, but some people claim their monkeys are service animals. Some probably are, since some monkeys are specially trained to help the disabled (especially people with spinal cord injuries). Monkeys can be very dangerous, yet it might be hard to look at any given monkey and say it poses a "direct threat" to another person. A properly trained and temperament-tested monkey is probably low risk and justifiable. But, proper training and temperament-testing aren't required by the ADA

Businesses that sell or prepare food must allow service animals in public areas even if state or local health codes prohibit animals on the premises.

  • Public health codes are there for a reason... to protect the health of the public. Therefore, careful consideration must be taken before breaking public health rules. The risks posed by a properly trained service dog are inconsequential, and properly trained and tested animals of appropriate species absolutely should have free access. Other species have different risks and these need to be considered. All animals are not created alike.

Violators of the ADA can be required to pay money damages and penalties.

  • This is good for true violations such as someone refusing access to someone with a trained seeing-eye dog. However, it also leads to difficulties excluding high risk situations.

I'm know I'm going to get nasty emails from people with various untested, unregulated (and probably untrained) "service animals," but I think this is an important issue. The ADA provides a great framework for ensuring proper access to and by service animals. However, I don't think it's clear enough. Vague acts create the potential for stretching the rules and violating the spirit of the law. I'd never advocate getting rid of this Act, however I think it needs to be rethought. There is a great need for a clearer definition of what constitutes a service animal. Service animals should be specially trained, temperament-tested and certified by an independent body. If someone thinks they need a service monkey or horse, the need for that should be clear and the animal should be properly trained and scrutinized. Otherwise, it's a pet and shouldn't be given the same access. Problems that occur from inappropriate "alleged" service animals risk unnecessary scrutiny of, and barriers to, real service animals.

If you disagree, please comment. However, don't just send me the typical "I have a service horse and you're an idiot" comment that comes through periodically. Tell me why you disagree with better defining species, training and certification.

Dog bites and MRSA

There's been a lot of talk (hype) in the press about pet bites and MRSA (methicillin-resistant Staphylococcus aureus). This relates to a paper in Lancet Infectious Diseases regarding infections associated with pet bites. Some press articles are more sensational than others, but most are taking the bite infection paper and building in unrelated comments about MRSA in animals to make it seem like there's a major MRSA dog bite epidemic underway.

I realize that MRSA is a hot topic that is easy for reporters to latch onto, but the problem is that the actual research related to MRSA is being taken out of context (and blown out of proportion). MRSA was certainly mentioned in the paper, but it was not the focus of the research nor do the authors play up concerns about pets as a source of MRSA infections. Nevertheless, the impression people are getting from many news articles is that there is rampant MRSA transmission by infected pets.

Is MRSA infection a potential concern after a dog bite?

  • Yes, but more because of the bite itself than the particular dog.  MRSA infections that occur after a dog bite are probably the result of contamination of the wound with MRSA from the person's own nose or from another person, for example during a visit to their physician/clinic/hospital. It's possible for MRSA to be in the mouth of the dog and for it to be transferred to the wound during the bite, but that's pretty unlikely. The person bitten or someone treating the wound is a more likely source of the bacterium. So, the bite was the ultimate "cause" of the MRSA infection, because the infection probably wouldn't have developed without that break to the body's normal defensive barriers (i.e. the skin), however the "source" of the infection was (in most cases) NOT the animal.  The same kind of infection could have happened with any similar type of trauma.

What should I do if I'm worried about MRSA and dog bites?

  • Worry more about dog bites than MRSA. Bites themselves are major problems, even if MRSA is not involved. The degree of trauma can be significant, and a variety of bacteria can cause serious bite infections, not just MRSA.
  • Take measures to reduce the risk of being bitten, both in terms of how you handle and train your dog and how you interact with other dogs.
  • If you are bitten, immediately clean the wound as thoroughly as possible. If the bite is over a joint, tendon (e.g. wrist/ankle), prosthesis or genitals, if there is significant trauma or if you have a weakened immune system, you need to see a physician. If you have any other concerns, get examined by a physician promptly.

More information on MRSA in animals can be found on the Worms & Germs Resources page.

Mycobacterium bovis... don't blame the cows?

I recently wrote about Mycobacterium bovis, the cause of bovine TB and a pathogen that can be transmitted to people and rarely to pets. A reader made the following comment:

"Having come across your very interesting blog, I was questioning/wondering whether your statement regarding Mycobacterium bovis, "whose main natural reservoir is cattle", is in fact actually so any longer; if ever. . In the UK all cattle herds were once declared clear of this disease by testing and culling and the gassing of badgers, until the government protected the badger over here to appease animal rights activists and gain a few extra votes.  Now it is rife again. These people somehow believe badgers have 'rights' to life above farmers' cattle.

I often wonder if the 'bovine' association is simply because the bacterium was first isolated in cattle as they were obviously captive and there to be investigated. Could it just as easily have been called Mycobacterium meles?  As I understand it, Mycobacterium tuberculosis came first and originated in humans and then developed as Mycobacterium bovis in animals"

Good question. Just because a disease is named after a particular species does not mean that it's the main source or original source of the pathogen responsible. Cowpox virus is a good example - cows aren't actually the reservoir of this virus, rodents are. However, because cows are more closely observed or monitored than rats, it was originally associated with cows and thus named cowpox.

We are more likely to detect diseases in humans first, followed by domestic animals, followed by wildlife. Severe acute respiratory syndrome (SARS) is a good example of this. This disease was first found in people. It was then linked to civets and raccoon dogs. However, civets and raccoon dogs aren't the true reservoirs, nor where the disease originated. It appears that the reservoir is in fact bats. Bats are a lot harder to investigate than captive animals, so even though they are now the presumed reservoir, it took a while to figure that out.

Back to Mycobacterium bovis... It's impossible to say for certain where it originated. Since it is thought to have evolved from Mycobacterium tuberculosis, the reservoir of which is people, it makes sense that the evolution of M. bovis would involve a domestic animal species instead of a wildlife species.  Cattle have much closer contact with people than do wildlife such as badgers, opossums and deer. So, since M. bovis has historically been most strongly associated with cattle, and cattle live in close contact with humans, I woudn't be surprised if they are the true orgin in this case. However, since M. bovis can infect a very wide range of species, we can never really know.

More about turtles and Salmonella

In response to recent posts about Salmonella and turtles, a reader posed these questions:

Okay, so turtles and tortoises can carry salmonella.  Does that mean that all do? 

  • Not all, but a lot of them do. Aquatic turtles are probably a greater risk than tortoises.

If a vet analyzes a poop sample from my Russian Tortoise and there is no Salmonella, does that mean we can quit worrying about it?

  • Unfortunately no. We can never be confident in declaring a reptile "Salmonella-free." Salmonella can be shed intermittently, so a single negative sample doesn't mean the reptile is truly negative. We don't know what the optimal testing protocol is in terms of what to sample, how often to do it and how many samples are needed. I'd never tell anyone a turtle or tortoise is Salmonella-free. To err on the side of caution, we have to assume that all reptiles are carrying Salmonella.

Conversely, if the poop does show Salmonella, is there any way to eliminate it from the tortoise and then quit worrying about it?  Our tortoise is isolated from other pets and only eats what we consider clean, fresh produce - so I am hoping the chance of reinfection would be minimal.

  • Unfortunately, no again. There's no proven way of eliminating Salmonella from a reptile. Getting rid of Salmonella in an animal that is a carrier is different than treating a typical bacterial infection. Salmonella is a commensal bacterium in reptiles, meaning it can be a normal component of the animal's bacterial microflora. It is very difficult to eliminate commensal bacteria since they have evolved to survive in (or on) their host. Unlike in clinical infections, which tend to be short term infections of a site where the bacterium does not normally live, using antibiotics to eliminate Salmonella carriage is unlikely to be successful. Giving antibiotics can also upset the normal intestinal bacterial population, which can actually make it more likely for bacteria like Salmonella to proliferate. Salmonella can also live inside intestinal cells, where most antibiotics can't reach them. Treatment, therefore, is unlikely to be ineffective, and might just result in increased antibiotic resistance (something we certainly want to avoid).

Check out the Worms & Germs Resources page for more information.

"The other TB" Mycobacterium bovis

Tuberculosis (TB) is an incredibly important disease caused by Mycobacterium tuberculosis. It's a huge problem internationally, and the problem is getting worse in many areas. Another cause of "tubercular" (or tuberculosis-like) disease is Mycobacterium bovis, a related microorganism whose main natural reservoir is cattle.

Mycobacterium bovis is cause of bovine TB. It can also infect people (usually through drinking or eating unpasteurized dairy products) and pets. Pets can be exposed by a few different routes, including eating contaminated dairy products, eating infected animals (e.g. snacking on carcasses of wildlife like deer that have died of the disease), and perhaps from direct exposure to wildlife carrying the organism. Mycobacterium bovis is an important problem in some areas, typically because of its presence in a wildlife reservoir like deer or the European badger (a major problem in the UK).

Mycobacterium bovis can cause serious disease in pets. It often causes non-specific signs that makes it hard to diagnose until disease is very advanced (and unfortunately likely beyond the point of successful treatment). Some groups recommend prompt euthanasia of infected pets without considering treatment because of the potential for infection of people. The risk of pet-human transmission is completely unclear, but it's such an important disease that some people think any risk is unnecessary and unjustifiable. So, the key is avoiding infection in the first place (for both people and pets). This is of particular concern in regions where M. bovis is present in wildlife and cattle. In areas where it is not known to be present, there should be little to worry about.

Here are some simple steps that can help you reduce the risk of your pet becoming exposed to M. bovis:

  • Keep cats indoors.
  • Don't allow dogs to roam free outdoors.
  • Don't allow animals to have access to unpasteurized dairy products or dead animals.

Pretty basic, isn't it?

EFSA Statement on MRSA in animals and food

The European Food Safety Authority, along with the European CDC and European Medicines Agency, have released a report about methicillin-resistant Staphylococcus aureus (MRSA) in livestock, pets and food. There's nothing too earth-shattering in it, and nothing more than what we've been saying all along, but some of the points are worth repeating.

  • While food may be contaminated with MRSA, there is currently no evidence that eating or handling MRSA-contaminated food leads to increased health risks in people.
  • Pets can be infected with MRSA, first acquiring it from people but then potentially transmitting it back to humans.
  • Transfer of MRSA to humans from companion animals and horses is difficult to control. (I don't agree with that). Basic hygiene measures are important before and after animal contact. Additionally, avoiding contact with nasal secretions, saliva and wounds is ideal.
  • Prudent use of antibiotics in animals should remain a key measure and monitoring of antibiotic use in animals should be performed to identify unnecessary use.
  • Drugs of last resort for the treatment of MRSA in humans should be avoided in animals.

Meningitis in a baby linked to pet cat

A paper in the Journal of Clinical Microbiology back in 2000 described a case of Pasteurella multocida meningitis in a one-month-old baby that was linked to a pet cat. Pasteurella multocida is a bacterium that can be commonly found in the mouth of healthy dogs and cats - 90% or more of healthy cats may have it in their mouth. The organism can cause infection in humans.  These cases are usually associated with close contact with animals, such as bites, scratches and licking wounds. In this case, there was reportedly little contact between the baby and the cat, yet the same P. multocida strain was found in both. The cat was healthy and the bacterium was found in its mouth. There was no clear route of transmission (like a bite or a scratch), however unidentified contact with the cat or (more likely) indirect transmission of the bacterium from the cat to the baby by another person are possible.

This is a good example of the unpredictable nature of zoonotic infections. There was no reported underlying disease that made this baby more susceptible to infection. It's just that being very young (or very old, or immunocompromised) means you're more likely to develop infections from the myriad bacteria that are present all around us. While this infection might not have been preventable, we need to think about good routine precautions involving contact of pets with babies.

  • Keep them apart (but not completely). Pets should not be allowed to lick or have other close contact with a young baby. That being said, household pets need to be around the baby to learn to interact with the child safely, and recognize the baby as a member of the family, but supervision is needed and direct contact should be avoided.
  • Good hygiene should be used around pets and babies (individually and together). Hands are the main source of disease transmission and regular hand washing is a great infection control tool.

Another dog cull in China

At the same time that the country is drafting an animal welfare law that would ban widespread killing of dogs, a Chinese city has killed 36 000 stray and pet dogs in an effort to eliminate rabies. Since late May 2009, more than 6 000 people in Hanzhong have been bitten or scratched (presumably by dogs), and 12 have died of rabies. Certainly, this indicates multiple problems. One is the massive number of bites and scratches. Contributing factors probably include a large stray animal population, limited routine animal control efforts, and inadequate education of the public regarding bite avoidance. The number of injuries and deaths certainly indicates that an aggressive response is needed. However, there is little evidence that culls (i.e. mass killings of this type) have any effect on controling rabies and animal-associated injuries. Efforts are probably better directed at other forms of population control, vaccination of stray and pet dogs, and education of the public to keep stray dogs away and reduce the risk of bites. These types programs cost money, but the costs of treating 6 000 bites and 12 fatal rabies infections can be enormous. I don't know how many people received post-exposure treatment for rabies, or what such treatment costs in China, but it's estimated to cost  about $1500 per person in North America. That would pay for a lot of rabies vaccine for dogs.

Photo: Hanzhong, China (source: www.panoramio.com)

Red eared slider turtle rebuttal

Following a report on black market turtle sales in Maryland, a letter to the Baltimore Sun by Maryland veterinarian Dr. Jeffery Rhody wanted to "set the record straight".

"All reptiles carry salmonella as part of the normal bacterial population in their body."

  • Not really true, however Salmonella can commonly be found in healthy reptiles, so the overall sentiment is valid.

"The risk of getting infected with salmonella from a reptile can be greatly reduced with common sense hygiene practices."

  • Absolutely. General infection control practices are critical to reduce (but they do not eliminate) the risk of Salmonella transmission.

"In fact, the incidence of reptile-borne salmonella infections is much less than salmonella infections obtained from improperly handled poultry products."

  • Statistics can be manipulated to either support or refute this. The absolute number of Salmonella cases from food is certainly greater than those from turtles. However, I'm not so sure turtles end up looking good when you consider the number of cases compared to the number of people exposed to these factors - a lot more people eat food than own turtles.  The number of cases of Salmonella associated with reptile contact every year is stunning, even though only a small percentage of people own reptiles. Fatal infections can occur, so it's not something to take lightly. Statements like the one above can get into some questionable logic, like saying that a machine gun can kill more people than a handgun, so handguns must be safe. Certainly, Salmonella is a risk with handling raw poultry, and efforts are taken to get people to reduce risky behaviours (like contaminating kitchen surfaces with raw meat). The same should apply to reducing risky behaviours with regard to pet contact.

"Of course, if you lick a turtle, the risk of salmonella infection is greatly increased."

  • Yep. That's why the focus is on small turtles. But, people get Salmonella from larger turtles too.

"No one who owns a slider should be concerned about breaking the law."

  • They should, however, be concerned about getting sick. Turtle owners should learn about risks and preventive measures from sources such as a the information sheet in our Resources page.

As someone who has owned turtles, I understand the appeal of these animals. As someone involved in zoonotic diseases, I understand the risks. People need to have enough information to understand the risks and benefits, to make logical, informed decisions. The risks to healthy adults who handle the animals properly is quite low. That's why the focus is on high risk households like those with young children, the elderly or immunocompromised individuals. There are good reasons for the ban on the sale of small turtles. Banning the sale of small turtles doesn't hurt anyone (except for people wanting to profit from selling them), and may prevent disease. Seems logical to me.

Black market turtles in Baltimore

There is apparently a thriving black market for baby red-eared slider turtles in Baltimore. The sale  (and possession) of small turtles is illegal in Maryland, like many other regions, largely because of public health concerns regarding Salmonella.

Over 100 hatchling turtles have been seized in the past 2 weeks. Baby turtles offer a good profit margin for black market vendors. They can be purchased from farms in the southern US for about $1 each and then resold for many times that amount. One person was caught selling turtles out of the back of a van. (Why anyone would buy anything from someone selling out of the back of a van is beyond me!)

People buy turtles thinking they make cute pets, not realizing what they need to do to keep them healthy as they grow. Turtles that are fortunate enough to be raised properly create another problem, since most people are not willing or able to take care of adult turtles that reach 10-12 inches in length. This can result in turtles being killed or abandoned.

Another major problem in the risk of Salmonella. Turtles very commonly carry this potentially harmful bacterium, and they are an important source of infection in people. The concerns are greatest with young children who may handle small turtles and put them in their mouths. People need to think before they buy. Before getting any pet, learn about the animal, including requirements for care and human health risks (and also if it's legal). A little common sense goes a long way.

More information about Salmonella and turtles can be found on the Worms & Germs Resources page.

Baylisascaris (raccoon roundworm) in cats

A reader posed this question, with respect to having raccoons living around the house:

"One thing that causes me concern with the raccoon roundworm is the possible danger of infection to my pets and myself through the feces left behind from the raccoons in the yard and possibly in my vegetable garden. Can I acquire the roundworm from working in the soil and/or from my root vegetables etc? My cats mingle near the raccoons, they don't bother each other, should I get my cats tested?"

Certainly, working outside (particularly in soil) leads to the potential for exposure to many disease-causing agents, including Baylisascaris, as well as dog and cat roundworms (Toxocara spp.). Eating unwashed/uncooked vegetables is also a risk. However, in the grand scheme of things, the risks to the average person (not very young or very old, functional imune system) are minimal, especially if basic hygiene measures are used, such as washing hands after working in the garden, and thoroughly washing vegetables. Raccoons tend to defecate in the same specific areas most of the time (raccoon latrines), so in general gardens probably aren't common sites for raccoon feces, although it certainly can occur. Cats are probably more likely to defecate in gardens. We shouldn't take concerns about Baylisascaris lightly, because even though disease (larval migrans) is very rare, it can be very severe.

Now, about testing cats for Baylisascaris - there's not much use, for several reasons:

1) The likelihood of a positive result is very low. The prevalence of Baylisascaris in dogs is very low. Little is known about the prevalence in cats specifically, but it is presumably very uncommon there as well.

2) It can be difficult to differentiate Baylisascaris from the feline roundworm, Toxocara cati. Unless the lab has experience with this, they may not be able to tell the difference. Therefore, you might get a misleading result.

3) What does a positive test tell you? It tells you that the cat is shedding this parasite or that is has ingested eggs that are just passing through the intestine.  The risk to people is still minimal if litterboxes are cleaned regularly. Contaminated stool is not infective until it has sat around for days to weeks, so regularly cleaning the litterbox and good handwashing can control the risk.

4) What does a negative test tell you? It tells you that the parasite was not detected on this single sample. It could have been there but not been identified. It might not be there today but could be there tomorrow (though this is still unlikely). A single negative test today does not tell you too much.

5) What would you do with the results? Probably not much. In the very unlikely chance that results were positive, it would likely be recommended to repeat testing to see if eggs are just passing through or whether the animal truly is infected with the parasite. That would determine whether treatment is needed. Otherwise, recommendations would be pretty much the same in both cases (good regular deworming program as directed by your veterinarian, proper handling of cat feces...).

The best way to prevent exposure of your cat to Baylisascaris (as well as other pathogens, predatory wildlife, vehicles, etc.) is to keep it inside.

Watch your step in Dutch parks

I recently wrote about a Dutch study of zoonotic parasites in pet feces and pets' haircoats. As part of that study, they asked pet owners about certain behaviours in their pets, and got some interesting answers.

60% of pets visit the bedroom (I'm surprised that's not higher), with 45% of dogs and 62% of cats allowed on the bed, and 18% of dogs and 30% of cats allowed to sleep in the bed with the owner.  While the UK's Chief Vet has warned against allowing pets into bedrooms and allowing them to sleep in people's beds, I don't have the same concerns - as long as common sense prevails.

45% of cats are "allowed" to jump on the kitchen sink. I don't know if they truly mean allowed, or whether the cats simply do this. I certainly don't "allow" my cat to be on the kitchen counter, but it's certain possible he is when I'm not looking. There are some potential concerns about pets hanging around food handling areas, so it's best to actively discourage this behaviour.

55% of owners clean their litterbox more often than twice a week. While daily cleaning is important for high risk people and high risk households, and is ideal for everyone, less frequent cleaning like this is acceptable for most people as long as it's done properly (See our Resources page for details about litterboxes).

15% of dog owners and 8% of cat owners reported always washing their hands after contact with their animals. This is surprisingly high - I wonder if it's really true, or whether some of those do it regularly but not always, or some think they should do it but don't really. Certainly, regular handwashing is important and it's ideal to do it after every animal contact, but that's admittedly hard to do in a household. I try to have good hand hygiene practices but I certainly don't always wash my hands everytime I should. Handwashing after every animal contact is more important for high risk people such as people with weakened immune systems.

39% of dog owners never clean up their dogs' feces. WHAT??!!  That's surprisingly high. When you consider how densely populated the Netherlands is, and that there are around 1.8 million dogs in the country, that's a lot of dog poop. That could be one reason why they found that dogs that were allowed off the leash outside were much more likely to have Toxocara eggs on their coat.

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Parasite exposure from pets

A recent study from the Netherlands investigated the prevalence of zoonotic parasites in pet feces and on pets' haircoats. The authors sampled feces and fur from dogs and cats, and looked for Toxocara (roundworms), Toxoplasma, Giardia and Cryptosporidium. All these parasites are of concern from a public health standpoint because they can be found in healthy pets and can also infect people.

Toxocara eggs were found on the haircoats of 12% of dogs and 3.4% of cats. Levels were low, ranging from 1-31 eggs per sample. An important aspect of this study was that they also assessed viability of these eggs, and found that none were viable.  Therefore, even though eggs were present, they were not relevant because they were dead. Exposure to UV light and lack of humiditiy were cited as possible reasons for the death of the eggs.

Toxocara were found in the feces of 4.4% of dogs and 4.6% of cats, which is consistent with other studies of healthy pets.

Toxoplasma was not found in the feces of any cat. (Cats are the hosts for this parasite so dogs weren't tested.)

Giardia was found in the feces of 15% of dogs and 13.6% of cats. However, when these strains were typed, the vast majority were species-specific types that do not cause disease in people. Only 2 of the 15 Giardia samples were assemblage A, a type that is transmissible from pets to people. This is very important to know because crude Giardia numbers don't tell you the whole story

Cryptosporidium was found in feces of 8.7% of dogs and 4.6% of cats. However, they were not able to type these parasites to determine if they were species that typically cause infection in humans, or whether they were Cryptosporidium felis or C. canis, which rarely cause disease in people.

The discussion section of the paper contains an interesting and relevant point about exposure to Toxocara eggs on the haircoat of pets. The authors state "Even in the worst case scenario of highly contaminated fur, e.g. with the highest Toxocara [eggs per gram] of 300 and an embryonated rate of 4% from the study of Wolfe and Wright, it is necessary to ingest more than 4 grams of hair, with 12 embryonated eggs per gram, to ingest 50 infective eggs."  Based on these data, exposure to parasites from the haircoat of pets is quite unlikely.  It might be a greater concern with stray or debilitated animals, or with puppies/kittens, who could have much greater coat contamination.

The take home message: Normal contact with healthy pets likely poses minimal risk of transmission of zoonotic parasites. That being said, regularly washing your hands is still a good idea because of the potential for exposure to other types of microorganisms (e.g. bacteria), and in rare circumstances where there may be large parasite burdens on a pet. Good deworming practices, particularly for puppies and kittens, also need to be considered.

Reference: Overgaauw et al, Veterinary Parasitology, 2009.

Are all Giardia created alike?

Giardia is a protozoal parasite that can cause diarrhea in multiple animal species. This microscopic parasite is a zoonotic pathogen that can be transmitted between animals and humans, and there are conerns about the role of pets in human disease.  Various studies have evaluated the presence of Giardia in healthy dogs and, to a lesser degree, cats. Typically these studies report that  about 7% of healthy dogs are shedding Giardia in their stool, but all Giardia are not the same in terms of the risk of transmission from dogs to humans. There are various types of Giardia, and some only infect specific animal species and not people. In dogs, assemblages (types) C and D are most commonly reported. These are considered canine-specific types and are therefore not a concern for transmission to humans. Assemblage A is an important zoonotic type which can infect dogs and humans, and this type can certainly be found in healthy dogs, but it seems to be relatively uncommon.

Emerging information about Giardia typing and zoonotic disease risks shows that this is a more complex issue than previously thought. Studies that determine the prevalence of Giardia shedding in dogs and cats are useful, but they only tell part of the story. Comments about the human health implications of Giardia shedding in pets can only be made when information about the Giardia assemblages found in these animals is also reported.

More information about Giardia can be found on the Worms & Germs Resources page.

Infection control best practices: French version

A comprehensive infection control document entitled "Infection Prevention and Control Best Practices for Small Animal Veterinary Clinics" was released last fall. A French translation has been completed and it now available on the Worms & Germs Resources page, as well as by clicking here.

This document is an excellent resource for small animal veterinary practices (in my completely biased opinion) and provides the most comprehensive description of infection control practices for small animal medicine. The field of veterinary hospital infection control is very much in its infancy, but guidelines such as this, combined with increasing interest and awareness by veterinary practitioners, will help increase routine infection control practices and hopefully reduce infectious disease transmission to patients, their owners and veterinary personnel.

Alternative heartworm treatments

Here's a recent question:

"We have a 'new' boxer age 2. The breeder believes in the raw food diet, and not many vaccinations or preventitive treatments. Recently the boxer has been shown to be heartworm positive, and she (the breeder) wants us to take a "holistic" approach to management. Are there any randomized trials to show any benefit to holistic treatment of heartworm?"

The quick answer is NO. There are no “holistic” treatments that have been shown to be effective in randomized trials, nor have any holistic treatments been shown to have any potential effect in in vitro studies. The only proven treatments are “conventional.” I consider it highly unethical to attempt other approaches because: 1) heartworm is a serious disease but one that can often be treated quite successfully and 2) untreated (or inadequately treated) dogs put other dogs at risk because they are sources of infection. Mosquitoes can transmit heartworm from infected dogs to other dogs in the area, and continue the cycle of infection. A serious and transmissible disease is not one for which unproven and likely ineffective treatments should be tried.

Heartworm is a potentially fatal disease that predominantly affects dogs, but can occasionally affect cats as well. It is most commonly caused by the parasite Dirofilaria immitis. It is spread by mosquitoes, which transmit the immature form of the parasite (microfilaria) which are found in the blood of infected animals. Upon being transmitted to a new host by a bite from an infected mosquito, the immature parasites eventually develop into adult worms. These worms lodge in the heart and the nearby blood vessels going to the lungs, and can cause a range of problems (e.g. lethargy, intolerance to exercise). Infection can be fatal - early (and effective) treatment is the key.