Worms and Germs Blog

Horse ownership and tetanus exposure

jsweese@uoguelph.ca (Scott Weese) — Fri, 10 Jul 2009 09:48:27 -0500

{This post is reproduced from a post on WormsAndGermsBlog's sister site, EquIDblog}

Here's a question I received the other day:

"Do people who work with animals and who work in barns need a tetanus shot as a result of this type of work? We have Therapeutic Riding Programs in the region and there is a sense that perhaps the volunteers and those who frequently tend the horses need to receive this. Is this the case?"

Tetanus is a disease that we are quite concerned about in horses because horses are very susceptible to it. That's why we vaccinate them yearly. Tetanus can also affect people, but is very rare (because of vaccination and lower susceptibility). While we pay a lot of attention to tetanus and horses, that does not mean that being around horses increases your likelihood of exposure to tetanus. The bacterium that causes tetanus, Clostridium tetani, is widely present in the environment. The more environmental (esp. soil) exposure that you have, the greater your risk of exposure. Being around horses doesn't increase your risk any more than doing other things outside.

Whether you have contact with horses or not should not change your approach towards tetanus. You should be vaccinated against tetanus every 10 years. Many (probably most, actually) adults are not up-to-date on tetanus vaccination. Adults tend not to voluntarily get booster shots and often this only happens when they have had a wound that requires medical care. (If you get stitches, they will almost certainly inquire about your last tetanus shot and give you another one if you haven't been vaccinated in the past 10 years).

More information about tetanus in horses is available in EquidBlog's Resources section.

Traveling parasite roadshow

jsweese@uoguelph.ca (Scott Weese) — Thu, 09 Jul 2009 20:58:18 -0500

There have been a few press articles lately about the Companion Animal Parasite Council (CAPC)'s traveling roadshow on parasitic zoonoses. Measures to increase awareness about zoonotic diseases and encourage appropriate preventive measures are needed, and traveling shows such as this have the potential to reach wide audiences. However, it's important for people to critically assess everything they are told and understand the sources. CAPC produces some excellent educational material but, to my knowledge, it is funded fully by the pharmaceutical industry. That doesn't necessarily mean that CAPC's educational efforts are suspect, and people participating with their roadshow have solid credentials, but you do have to critique some of the things CAPC says.

In one news article about CAPC's efforts, it is stated that "The CDC reports that about 14 percent of the total U.S. population is currently infected with Toxocara, or internal roundworms, contracted from dogs and cats." I don't think that's accurate information. I believe that this is based on seroprevalence data...the percentage of people with antibodies against Toxocara. The presence of antibodies in circulation means that at some point in life the body has been exposed to Toxocara and produced antibodies but it does not mean that people were ever sick and it certainly does not mean that people are currently infected. Toxocara can cause serious infections and is a concern in some regions (although it's extremely rare in Ontario) so we have to pay attention to it....but we have to take a balanced and evidence-based approach.

One common theme in all of the reports that I've read lately is the statement that "The CAPC recommends that pet owners use preventive medicine year-round to control internal and external parasites for the life of their cat or dog, no matter where they live." There's simply no evidence supporting this broad of a statement. Risks in warm southern climates are not the same as in northern areas with cold winters. Prevalence rates of different parasites vary greatly between regions. There is no evidence supporting year-round deworming for all regions. Statements like this weaken the other good educational information they have, particularly when you consider their funding source.

Don't disregard educational materials from CAPC or other industry-sponsored groups, just don't accept them as gospel. Critically assess, and don't be afraid to ask for facts or to get information from other sources.

More information about deworming recommendations for Canada were presented in an earlier post.

Cats and Q-fever

jsweese@uoguelph.ca (Scott Weese) — Tue, 07 Jul 2009 19:46:47 -0500

I was reading an interesting old paper the other day about Q-fever in cats. Q-fever is a zoonotic disease caused by Coxiella burnetii. It is most commonly associated with contact with sheep, cattle and to a lesser extent goats, around the time they give birth. This bacterium is highly infectious and it only takes a small number of bacteria to cause disease. (That's one of the reasons it's classified as an important bioterrorism agent).

While most of the focus in on ruminants, there have been many reports of Q-fever associated with cats (mainly contact with cats around the time they give birth) and cats may be the most important Q-fever reservoir in urban areas.

The study, a 1988 article from the journal Chest, describes a Q-fever outbreak in a town in Nova Scotia. 33 people were infected in the town of Baddeck (population 900, meaning 2.8% of the population was affected). 42% of infected individuals lived in 4 side-by-side buildings. Investigation revealed that most infected people reported had contact with a cat that have given birth to stillborn kittens (stillbirths are common in cats infected with Coxiella). The cat lived in one of those 4 buildings and regularly visited neighbouring buildings.

This is just one of many reports of Q-fever associated with cats. Almost all involve direct contact or being in the vicinity of cats around the time of birth. Since this bacterium is so infectious and can be spread through the air through aerosols, direct contact is not required for infection to occur.

Cat-associated Q-fever is probably pretty uncommon but Q-fever can be a very serious disease. Since it mostly involves cats at the time of delivery, a few basic measures should be able to greatly reduce the risks.

Avoid contact with cats that are giving birth or who have done so recently.
Avoid contact with newborn kittens and areas contaminated during the birthing process.
If your cat is going to give birth, try to have it do so in a well-ventilated areas away from areas where people spend time and away from areas where food is prepared.
If contact with the mother cat, kittens or areas/items contamination with uterine fluids is likely to occur, gloves should be worn. Hands should be washed after gloves are removed.
If cats give birth inside, the area should be thoroughly cleaned and disinfected after. Gloves should be worn for this.
The risks are probably higher with stray cats (who are more likely to be infected), so extra care should be taken to avoid contact with stray cats around the time of birth.

Dogs and swimming pools

jsweese@uoguelph.ca (Scott Weese) — Mon, 06 Jul 2009 10:00:39 -0500

My dog, like most labs, loves to swim (actually, she's incredibly lazy and prefers to wallow in the water, not actually exert herself). Many dogs like her often go into swimming pools in the summer, which leads to the question 'Is there an infectious disease risk?"

The honest answer is we don't really know. The reasonable answer is the risks are pretty low, especially with some common sense. You are probably more likely to get a pool-associated infection from another person than a dog, but the risks are not zero. (A dog is probably less likely to defecate in the pool than an infant or toddler!)

Various infectious diseases such as cryptosporidiosis, norovirus infection and E. coli O157 have been linked to swimming pools; all associated with transmission from people. As with most infections, the very young, elderly, immunocompromised and pregnant women are at higher risk.

Like many things in life, there is some degree of risk but you have to consider the risks and benefits together. The overall risk of infection from swimming with a pet in a well-maintained pool is quite low. The risks is probably even lower in a household pool (where dogs would have access) compared to a heavily-used public pool. Good general practices can reduce the risks. Chlorine can kill most (but not all) possible causes of infectious diarrhea, but it doesn't work instantly. If someone or something contaminates the pool, there is a window of opportunity that may last minutes to hours, for transmission of infection. Some causes of disease can survive for days, if not more. Therefore, chlorination is useful but not fool-proof.

Keep dogs that have vomiting, diarrhea or skin infections out of the pool. Dogs that have had diarrhea should probably be kept out of the pool for a couple weeks.
Don't allow dogs known to be shedding infectious agents like Salmonella and Giardia in the pool. Some healthy dogs shed these organisms and it's certain that infected dogs go into pools with no problems, but if you know that a dog is shedding an infectious agent it shouldn't be in a pool.
Don't allow dogs that have fecal staining of their haircoat in the pool.
The same rules should apply to people. People with diarrhea should stay out of the pool since they are probably a greater risk. It has been recommended that people not use a pool if they've had diarrhea in the past week.

The CDC has a good site about recreational water illnesses, which can be accessed by clicking here.

Kids exposed to rabies from stray kitten

jsweese@uoguelph.ca (Scott Weese) — Thu, 02 Jul 2009 16:49:21 -0500

Two kids and one adult are undergoing post-exposure treatment for rabies after having contact with an infected kitten. One child saw the stray animal and went to give it some food. He was bitten in the process. The kitten then proceeded to bite his mother and another child in the neighbourhood. Fortunately, the kitten was taken to animal control and was identified as a rabies suspect. It was euthanized and testing of the brain confirmed it had rabies. Accordingly, the 3 bitten people are now undergoing post-exposure treatment. Animal control is handing out flyers in the neighbourhood. One particular concern is that with young kittens, you can sometime find multiple animals from the litter infected and there may be more cute but deadly kittens in the area.

Avoid contact with stray animals. That's the best way to avoid getting bitten by one.
If you are bitten by a stray animal, the animal must be caught and quarantined. If you don't know the rabies status of an animal that has bitten you, you have to consider it rabid and get treated. If you are bitten, call animal control to catch the animal. If you can safely contain it (i.e. lock it in a garage) where it can be caught by animal control personnel and not put other people at risk, do that.
Vaccinate your pets.

Rabies quarantine

jsweese@uoguelph.ca (Scott Weese) — Tue, 30 Jun 2009 07:21:23 -0500

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

After biting someone
After potentially being exposed to a rabid animal.

The timeframe for these is quite different because what the quarantine is designed to accomplish.

Animals that have bitten someone are quarantined for 10 days so that they can be observed to see if they develop signs of rabies. This is important because most animals that bite do not have rabies and this is the easiest way of determining whether there may be a rabies risk from the bite. The reason behind the 10 day period is that if an animal was rabid and infectious at the time of biting, it would be dead within 10 days. Animals can only transmit rabies virus after it has reached the brain and started to spread outwards on 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 all exposed people...something we want to avoid if at all possible.

The second type of quarantine is based on less solid evidence. The idea behind it is to allow time to see if an animal that might have been exposed to rabies develops disease. For example, if an unvaccinated dog gets into a fit 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 with region. This will help reduce further rabies transmission be 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 in this approach is the incubation period of rabies, which can be long. There is not a lot of objective research to base the 6 month duration on (unlike the 10 day quarantine described above). After 6 months, it's very unlikely the dog will come down with rabies but I don't think we can ever 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 were exposed will develop rabies, so it's a reasonable timeframe. 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.

More information about rabies can be found in our Resources section.

Canine influenza vaccination

jsweese@uoguelph.ca (Scott Weese) — Mon, 29 Jun 2009 08:36:21 -0500

A canine influenza virus vaccine has recently been released. Canine influenza is 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 cause serious (including fatal) infections. These are most common in concentrated, stressful environments like shelters and racing greyhound facilities.

Like most vaccines, this 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 antibiotics 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 will be effective at reducing the incidence and severity of disease, as with influenza vaccines in other species. Basically, it means that if a vaccinated dog gets exposed, it should be less likely to get sick and if it gets sick, it should be less likely to have severe disease. 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 disease. In an otherwise healthy dog that is not in a high risk environment (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 vet 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 from: http://www.petinsurance.com/healthzone/pet-articles/pet-health/Canine-Influenza.aspx

Antibiotics: how about a dose of common sense

jsweese@uoguelph.ca (Scott Weese) — Fri, 26 Jun 2009 19:29:24 -0500

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, the approach to them 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 impacts of restriction 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 and a concerted, broad-based effort is needed.

Back to the topic at hand...

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 an MD or DVM. That wouldn't solve all our problems but would be a great start. One case from my time in private practice stands out, although it certainly wasn't too uncommon. It was a steer with a broken leg. The farmer had noticed that the animal wasn't using the leg and tried treating it penicillin for a few days (which, surprise, surprise, didn't work). 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 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 your 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, however are we going to take the bigger steps required to address this issue?

More on service animals and access

jsweese@uoguelph.ca (Scott Weese) — Fri, 26 Jun 2009 16:45:45 -0500

Recently, I wrote a commentary about the need to better define what service animals are because of potential abuses and possibility that illegitimate use could impact real 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 concerns. What constitutes 'owner trained'? Service animals are highly trained to do their specific task and to safely work in public situations. I'm not convinced owner training makes a service animal. There needs to be at least some degree of oversight 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. Protections need to be in place for true service animals. As importantly, there needs to be education about what service animals are, what they do, and where they should be allowed to go. I also think your 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 raise problems. If you never know whether a 'service' animal is really a service animal, then you 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, not 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.

Recommended changes in US rabies exposure protocol

jsweese@uoguelph.ca (Scott Weese) — Fri, 26 Jun 2009 08:16:14 -0500

Currently, people that have potentially been exposed to rabies undergo post-exposure treatment consisting of one dose of 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 shots 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 particularly 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 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, you get a pretty big cost savings.

An interesting aspect of this is that the recommendations have been made without coordination with vaccine makers. Therefore, if this change is adopted, physicians would have to make a decision 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 liabilty and discussions wiht 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 in our Resources section.

A need for better definition of service animals

jsweese@uoguelph.ca (Scott Weese) — Wed, 24 Jun 2009 14:13:28 -0500

Because service animals are so important to some people, they have much greater access than other animals. In the US, the Americans with Disabilities Act (ADA) specifically addressed service animal access issues. It was a landmark act that ensured proper 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 vague aspects of this Act can lead to abuses and unwanted scrutiny on 'real' service animals. I was at an infection control conference recently and numerous people commented on problems they have had with alleged service animals, the inability to find out whether they are really service animals and the potential legal implications of trying to do anything. These problems mainly involve people with questionable service animals.

The reasons that problems occur is because of a combination of strong and vague statements in the Act.

One problem is the what constitutes a service animal: "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 what 'trained' means and no requirement for formal training or certification, not restrictions of certain animal species. I could say that my sheep are trained to do something and take them into a restaurant with me.

Some other key points in the Act.

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 but some people claim their monkeys are service animals. Some probably are, since some monkeys are specially trained to help (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'. A properly trained and temperament tested monkey is probably low risk and justifable. 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 proper 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 area. 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 improper service animals risk unnecessary scrutiny of 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 what you disagree with better defining species, training and certification.

Dog bites and MRSA

jsweese@uoguelph.ca (Scott Weese) — Tue, 23 Jun 2009 18:37:48 -0500

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 blown out of context. MRSA was certainly mentioned here but was not the focus of the research nor do the authors play up concerns about pets as a source of MRSA infetions. 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 from a dog bite?

Yes, but more because of the bite component than the dog. By that, I mean that MRSA infections that occur after a dog bite are probably the result of MRSA being deposited into the wound from the person's nasal passages or during a visit to the physician/hospital. It's possible that MRSA could have been in the mouth of the dog and transferred to the wound during the bite, but that's pretty unlikely. The bitten person or soemone treating the wound is a more likely source of infection. 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, however the same thing could have happened with any similar form of trauma.

What do you do if you're 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 major 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. If the bite is over a joint, tendon, prosthesis or genitals, if there is significant trauma or if you have a compromised immune system, you need antibiotics. If you have any concerns, get examined by a physician promptly.

More information on MRSA in animals can be found in our Resources section.

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

jsweese@uoguelph.ca (Scott Weese) — Tue, 23 Jun 2009 08:46:13 -0500

I recently wrote about Mycobacterium bovis, the cause of bovine TB and a pathogen that can be transmitted to people and rarely 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"

It's a good question. Just because a disease is named after a species does not mean that it's the main source. Cowpox virus is a good example of that. Cows aren't actually the reservoir of this virus, rodents are. Because cows are observed closer than rats, it was originally associated with cows and named cowpox.

Just because a microorganism was first found in an individual species does not mean that it originated there or that it is most common there. We are more likely to detect diseases in humans, followed by domestic animals, followed by wildlife. SARS is a good example of that. 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 or where the disease originated. It appears that the reservoir is bats. Bats are a lot harder to investigate than captive animals, so despite them now being the presumed reservoir, it took a while to figure that out.

Back to Mycobacterium bovis.... It's impossible to say definitively where it originated. Given it is thought to have evolved from Mycobacterium tuberculosis, whose reservoir is people, it makes sense that the evolution of M. bovis would involve a domestic animal instead of a wild animal, because of the closer contact of people with domestic cattle versus other wildlife reseroirs 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. However, since M. bovis can infect a very wide range of species, you never know.

More about turtles and Salmonella

jsweese@uoguelph.ca (Scott Weese) — Mon, 22 Jun 2009 18:10:17 -0500

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 negative. We don't know optimal testing protocols 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 eradicate commensal bacteria since they have evolved to survive in their host. Unlike clinical infections which tend to be short term infections of a site where the bacterium does not normally reside, using antibiotics to eliminate Salmonella carriage is unlikely to be successful. Giving antibiotics can upset the normal gastrointestinal bacterial population, something that can be it more likely for bacteria like Salmonella to proliferate. Salmonella can also live in intestinal cells, where most antibiotics don't adequately penetrate. Treatment, therefore, is unlikely to be effective and might just result in increased antibiotic resistance, something we certainly want to avoid.

Check out our Resources section for more information.

"The other TB", Mycobacterium bovis

jsweese@uoguelph.ca (Scott Weese) — Sun, 21 Jun 2009 13:42:01 -0500

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

Mycobacterium bovis is cause of bovine TB. It can also infect people (usually though consumption of unpasteurized dairy products) and pets. Pets can be exposed from a few different routes, including ingestion of contaminated dairy products, ingestion of infected animals (usually from snacking on carcasses of wildlife like deer that have died of the disease) and perhaps from direct exposure to wildlife carrying the organism. M. 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). M. 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 perhaps beyond the point of successful treatment). Further, some groups recommend prompt euthanasia of infected pets without the option of 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. 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, you should have little to worry about.

How can you reduce the risk of your pet becoming exposed?

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

jsweese@uoguelph.ca (Scott Weese) — Fri, 19 Jun 2009 08:14:18 -0500

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, but some of the points are worth repeating.

While food may be contaminated with MRSA, there is currently no evidence that eating or handling contaminated food can lead to increased heatlh risk 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

jsweese@uoguelph.ca (Scott Weese) — Wed, 17 Jun 2009 13:03:38 -0500

A 2000 paper in the Journal of Clinical Microbiology described a case of Pasteurella multocida meningitis in a 1 month old baby that was linked to a pet cat. Pasteurella multocida is a bacterium that can be commonly found in the oral cavity of healthy dogs and cats. 90% or more of healthy cats may have it in their mouth. Human infections can occur and 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 cat, yet the same P. multocida strain was found in cat and baby. The cat was healthy and the bacterium was found in its mouth. There was no clear route of transmission, however unidentified contact with the cat or (more likely) indirect transmission of the bacterium from the cat to the baby by other people 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. 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 pets and babies.

Keep them apart...(not not completely). Pets should not be allowed to lick or have other close contact with young babies. Household pets need to be around the babies, learn to interact with them safely and recognize them as a member of the family, but supervision is needed and direct contact should be avoided.
Good hygiene measures 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

jsweese@uoguelph.ca (Scott Weese) — Tue, 16 Jun 2009 16:21:56 -0500

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 36000 stray and pet dogs in an effort to eliminate rabies. Since late May, more than 6000 people have been bitten or scratched, and 12 have died of rabies. Certainly, that indicates multiple problems. One is the massive number of bites and scratches. Contributing factors probably include a large stray 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's little evidence that culls have any effect. 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 6000 bites and 12 fatal infections can be enormous. I don't know how many people received post-exposure treatment for rabies and what it costs in China, but it's estimated to cost ~$1500 in North America. That covers a lot of rabies vaccine for dogs.

Red eared slider rebuttal

jsweese@uoguelph.ca (Scott Weese) — Sun, 14 Jun 2009 21:58:57 -0500

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 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 exposure. (A lot more people eat than own turtles).The number of cases of Salmonella associated with reptile contact every year is stunning even though 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 the questionable logic that a machine gun can kill more people than a handgun, so handguns must be safe. Certainly, Salmonella is a risk from handling raw poultry, and efforts are taken to get people to reduce risky behaviour. The same should apply 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 section.

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 a logical, informed decision. 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

jsweese@uoguelph.ca (Scott Weese) — Fri, 12 Jun 2009 15:15:03 -0500

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 ~$1 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 a cute pet, not realizing what they need to do to keep them healthy as they grow. Turtles that are fortunate enough to be raised properly and grow 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 salmonellosis. Turtles 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, people need to 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 in our Resources section.