Groundhog day - Not again!
If a groundhog sees its shadow, there's more winter on the way. If it doesn't see its shadow, spring is coming soon. So what does it mean when a groundhog attacks a cop?
An aggressive groundhog in New Jersey that tried to attack two police officers and one other person was confirmed to have rabies. Police were called to a house because the groundhog in the garage charged the house owner as he tried to get into his truck. The groundhog was subdued with pepper spray (I wonder if anyone has every used a Taser on a groundhog), caught, euthanized and tested for rabies. Fortunately, none of the people came in direct contact with the animal, therefore there was no exposure and rabies post-exposure prophylaxis was not required.
Groundhogs are not high on the list of animals that tend to get rabies. One-hundred twenty-three rabid groundhogs have been identified in the state since 1989 (I'm actually surprised it's that high), compared to 4 175 raccoons. Like every other mammal, groundhogs are susceptible to rabies virus but they are less likely to carry the virus, because they are rather shy vegetarians and would often not survive attacks from rabid predators. This case is a good reminder that rabies must be considered in any animal acting strangely.
MRSA testing and false advertising
I received a flyer from Zoologix, a company that offers various (typically unvalidated and unproven) PCR tests for animals. The flyer headline was "Pets can carry MRSA - but testing can help."
Testing in certain situations is useful, but this is almost always limited to diagnosis of animals with active infections (i.e. they're sick). PCR is not a good way to make such a diagnosis, because the test doesn't tell you anything about the bacterium's susceptibility to other antibiotics. Screening of pets just to determine whether or not they carry MRSA is rarely needed, and currently there is no evidence that PCR is a reasonable test for this.
There are no validated PCR tests for MRSA in animals. We looked at using a human test in horses and it failed miserably. There are validated tests for use in people, and they are quite good: they accurately identify MRSA and differentiate it from other methicillin-resistant staphylococci and from methicillin-susceptible S. aureus. That's critical, because you have to know what a positive test really means.
I called the company and asked what the test actually detects. They said it detects the mecA gene, the gene that confers methicillin-resistance to staphylococci such as S. aureus. However, this gene can be present in other staphylococci that can be found in many healthy dogs and cats (10-30% in some studies). It does not actually detect MRSA and a large percentage of samples that give positive results will be false positives. The tests that are used in humans are specifically designed to look at two things in combination: whether S. aureus is present and whether it has the mecA gene (methicillin-resistance). This is the right approach because it excludes all those other false positives. Detecting mecA alone is completely useless. It's interesting that the flyer states "PCR testing is fast, effective and accurately differentiates MRSA from other bacteria - even other Staph strains." Based on what the company told me over the phone, with regard to the test they're advertising, that's a blatant lie.
This is an example of a combination of bad science and bad ethics. This company has no business marketing this test. It's false advertising, because the test isn't an MRSA test. Their justification for using it is similarly weak. Anyone thinking about using this test should run away quickly! The issues with this test (and others) should also be considered when deciding whether to use this company for any tests.
More (and accurate) information about MRSA can be found on the Worms & Germs Resources page.
All natural organic antibiotic?
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A recent press release from All Pet Naturals proclaims "First All Natural Organic Antibiotic for Pets Now Available."
I know that "organic" and "all natural" are big catch-words for some people, and may be mistakenly perceived as indicators of safety or quality. There are very good reasons why we used manufactured and tested pharmaceuticals. If I wanted an organic, all natural approach to antibiotic therapy, I could eat some moldy bread and hope that an antibiotic-producing yeast was present, hope that it was producing adequate levels of antibiotic to fight my infection, hope that the antibiotic would survive the acid environment of my stomach and be absorbed into my bloodstream, and hope that it would kill the bacterium that's making me sick. Doesn't sound like a good idea to me. Personally, if I need any antibiotic, I'd rather use one that has been shown to be effective, is produced using good manufacturing practices, can be taken at a known concentration and has good dosing recommendations, among other things. Playing around with unknowns in the face of a bacterial infection is not a good idea.
Back to the supposed "all natural organic antibiotic" product in question. It is a grape seed and grapefruit seed extract product. Those compounds have some biocidal activities, meaning they can have effects on some bacteria and viruses in laboratory tests. Evidence for its use for treatment of disease is less convincing, but some topical biocides may be useful adjunctive treatments for skin infections. The manufacturers claim that this product can be used to:
- Treat skin problems caused by bacteria, even basic cuts and wounds.
- Fight tooth decay and gum disease, prevent free-radical damage to the lens and retina of the eye, and even treat glaucoma by protecting collagen structures in the eye.
- Help relieve asthma and emphysema.
- Help to support brain function with daily use.
I have a general line when it comes to products like these: the more a product claims to cure, the less likely it's going to do anything. There's simply little to no evidence for these claims. (Making health claims like this for a nutraceutical is also illegal.) I hate seeing animals that have suffered because people used products like these instead of recommended antibiotic therapy.
Products like this are typically harmless (unless they are used instead of proper treatment and medications) but, if you need an antibiotic, use a real antibiotic. If there's no clear evidence of need, don't use anything. Any compound with activity against bacteria, whether it's a traditional pharmaceutical antibiotic, an organic alternative or a disinfectant, can exert pressure for development of further resistance. So, we only want to risk that if it's really necessary. It's another example of the need to think, read, critically assess and ask questions about potential treatments before jumping on "all natural organic" bandwagon.
Zebra sidelines football player
No, I'm not talking about a referee, I'm talking about a real zebra. Pittsburgh State football player Joe Windscheffel will miss the entire upcoming season after being attacked by a zebra on a farm in Kansas. In a related story, Kansas State University Professor Gary West remarked about various problems associated with people owning exotic pets. Some are pretty clear, such as the risks posed by 500 lbs tigers or 20 ft pythons (or unruley zebras). Others are more insidious, such as the risks of transmitting various zoonotic diseases.
Exotic pets are an important source of zoonotic diseases. Some of these diseases, like Salmonella, are very common and well-understood. Others come out of nowhere and can cause major problems, such as the monkeypox outbreak in the US a few years ago that was caused by prairie dogs and African rodents. One problem with exotic pets is that we know little about the disease risks associated with them, and therefore we don't know what precautions should be taken or how to test them for the most important pathogens. While exotic pets can be interesting, they certainly pose an increased risk of disease compared to dogs, cats and other domestic animals for which we have a good idea of the risks involved and how to manage them. That's not to say that all exotic pets will cause disease and no dogs will - that's definitely not true. However, people having contact with exotic pets must accept an increased risk of disease exposure.
The CDC recommends that children under five years of age, elderly individuals, people with compromised immune systems and pregnant women not have contact with exotic pets. While these are the high risk groups, infections can occur in anyone. If you really want an exotic pet:
- Stop, think, and read as much as you can before making the decision. Find out about the animal, how to care for it and what risks might be involved.
- Make sure you can provide appropriate care. Many exotic pets die because of poor management because they're owners can't or don't know how to care for them properly.
- Find a captive bred animal, as these animals likely pose less risk of harbouring exotic diseases. It's also a much more humane way to get a pet than to buy a wild caught animal (especially when you consider that many animals die during capture and transit).
- Make sure there are no high-risk people living in or visiting the household. Saying they will be in the house but won't have contact with the pet is not adequate, because infections from indirect contact can occur.
- Remember that if you do things right, your pet should live for a while (e.g. years). If you think you might want to have kids in a couple of years, do you really want to get an exotic pet that will need to be re-homed at that time?
- Make sure your physician knows you have an exotic pet. Various diseases that would not be an issue for the general population might need to be considered if you get sick.
Image source: University of Bergamo
Salmonella Apapa from a reptile
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A recent case report in the Journal of Clinical Microbiology (Cooke et al. 2009) described isolation of Salmonella Apapa from the feces of a 67-year-old woman with abdominal pain. The patient had a history of various medical disorders but no clear evidence of a compromised immune system. She was hospitalized, and Salmonella Apapa was identified from a stool sample collected the day after admission. Fortunately, her abdominal disease resolved (whether it was caused by Salmonella or whether Salmonella was an incidental finding can't be stated definitively), and she was ultimately discharged from the hospital.
Salmonella diagnoses usually lead quickly to questions about food and reptiles. In this case, the woman's son had recently moved in with her, along with his two bearded dragons. The lizards were kept in a tank, and the woman reported having no direct contact with them. Samples from the lizards' feces and the tank environment were collected, and the same Salmonella strain was isolated. While getting Salmonella from a reptile is certainly nothing new, this case report highlights some important points.
- The person that was infected did not report any contact with the reptiles or their tank. Therefore, some type of indirect exposure must have occurred. This is why reptiles should not be kept in high-risk households even if the high-risk people don't have direct contact with them. High-risk households include households with young children (less than 5 years of age), elderly individuals, pregnant women and immunocompromised individuals.
- It's not just high-risk people that get sick. This person was perhaps on the crux of being considered high-risk based on her age and previous medical problems, but she was certainly not a clear example of the people we assume are at higher risk. A huge number of reptile-asociated cases of salmonellosis are reported every year. While high-risk people are more likely to get sick (and more likely to develop severe illness), healthy individuals can be infected as well.
Reptiles can make good pets. I used to have a pair of Red-Footed tortoises, so I'm certainly not anti-reptile (despite what the emails I typically get after posts like this say). People who have or who are comtemplating getting a reptile for a pet need to be aware of the associated risks, as they are certainly real and should be taken seriously.
Brucella canis: the other Brucella
Brucellosis can be a pretty nasty disease. Most people with brucellosis are infected through ingestion of contaminated food or contact with infected farm animals. Brucella abortus, B. melitensis and B. suis are the most common bacterial species involved. However, there is also another Brucella species, B. canis, which (as the name implies) is associated with dogs. Human infections with B. canis are much less commonly diagnosed than those caused by other Brucella species, but it is possible that this infection actually occurs more often than we realize.
Brucellosis can cause a wide range of problems, but most are rather non-specific such as fever, headache, body aches, sweating and back pain. Recurrent, undulating fever is a common sign and can persist for long periods of time. Disease caused by B. canis is similar to that caused by other Brucella species, but one reason this disease may be underdiagnosed is that screening tests for brucellosis do not cross-react with B. canis. Therefore, a physician might suspect brucellosis, but if the initial test (an antibody test) is negative, the physician is likely to move on to investigate other possibile diagnoses. Specific B. canis blood tests or culture of B. canis from blood or infected sites are required for diagnosis. Overall, it's probably still a very rare disease, but one that certain people should be aware of.
Many dogs that are infected with B. canis have no detectable signs of infection. The bacterium can circulate through the body continually or intermittently, and spread from the gentials (where it likes to reside) for years. Some infected dogs show signs of illness. Reproductive problems, including late-term abortion (miscarriage) and decreased fertility are major problems. Fever, lymph node swelling, diskospondylitis (infection in the spine) and other problems can also develop.
The risk of human exposure is highest in people in close contact with breeding animals, particularly people in contact with dogs that miscarry during pregnancy or kennels with reproductive problems. Most reported human infections involve people in close contact with dogs that miscarry. The risk to owners of household pets (especially neutered pets) is presumably very low.
- People who have been exposed to dogs that miscarry and who subsequently develop signs like fever and aches should make sure their physician considers B. canis infection.
- HIgh risk people (very young, elderly, immunocompromised, or pregnant women) should avoid contact with dogs that have miscarried, or dogs from kennels with reproductive problems or known B. canis infection.
- Care should be taken when handling dogs that have miscarried or are in the process of doing so. Gloves should be worn when handling the dog, aborted fetuses and any potentially contaminated items. Uterine (birth) fluids can have very high levels of B. canis.
- Hands should be washed regularly and after removal of gloves.
- If abortion or reproductive problems are identified in a kennel, testing for B. canis should be performed. If present, an eradication program should be started.
More information on brucellosis in dogs can be found in the Worms & Germs archives.
Leave the rabid cat at home next time
A stray cat taken by someone to a family gathering in Delaware, USA, resulted in 17 people from 4 states undergoing rabies post-exposure treatment. The kitten was found by the side of the road, taken to the gathering (it's unclear whether it was found on the way there or earlier), and when it became ill after the gathering, it was diagnosed with rabies. This is just one example of the potential for widespread exposure of people handling stray (or recently stray) animals at events like reunions, flea markets and sports tournaments. Because these animals (especially cute little ones like kittens) often get handled by a lot of people, a lot of people can be exposed to rabies if the animals are carrying the virus. These situations create major problems for public health personnel, because it's difficult to identify all the individuals who were potentially exposed when they are dispersed across the country.
While generally uncommon, this type of scenario happens a few times a year.
- Don't bring stray, or recently adopted, animals to public events.
- Ensure that your animals are properly vaccinated against rabies. Animals that have not been properly vaccinated should not be taken to public events.
- Don't handle stray animals.
- If an animal that you have recently adopted gets sick, make sure rabies is considered and, if necessary, make sure the animal gets tested.
More on Giardia in healthy dogs
New research provides more information on the debate about testing and treating of healthy dogs for Giardia. Two abstracts on the subject by researchers at Colorado State University were presented at the recent American College of Veterinary Internal Medicine conference.
In the first study (Clark et al), fecal samples were collected from 220 healthy dogs. Giardia was detected in 11.4% of samples, but no dogs carried assemblages (types) known to cause disease in people.
In the second study (Lappin et al), they evaluated whether treatment of healthy dogs that were shedding Giardia would eliminated the parasite. Sixteen infected dogs were treated with either fenbendazole or nitazoxanide. Eight (50%) of the dogs had to be removed from the study because of adverse effects from treatment! Of the dogs that completed the study, Giardia was still detected in 63% of dogs 34 days after treatment, indicating that the infection wasn't eliminated or that dogs were quickly re-infected.
These studies provide more support of the notion that there is no indication to test or treat healthy dogs for Giardia. Testing makes no sense when the parasite is so common but most infected dogs are healthy, and when strains carried by infected dogs are usually of no consequence to people. Giardia is essentially a normal part of the intestinal microflora in many healthy dogs. Treatment of healthy carriers isn't indicated because it can make dogs sick and because it doesn't work very well. Remember: above all do no harm.
The bottom line is don't bother testing healthy dogs for Giardia or treating healthy dogs in normal households.
Transmission of herpesvirus from a person to a rabbit
A paper in the July 1 edition of the Journal of the American Veterinary Medical Association (Muller et al) describes a case of encephalitis (brain inflammation) in a rabbit caused by human herpesvirus type 1. The owner had a severe herpes infection with genital and oral lesions five days before the rabbit got sick, and reported "intensive" nose-to-nose and mouth-to-nose contact with the rabbit. The rabbit started off with a decreased appetite and excessive tear production (epiphora) in one eye. Then other signs of eye and neurological disease developed. Despite aggressive treatment, the rabbit deteriorated and was euthanized after a week of hospitalization. Subsequent testing identified human herpesvirus type 1 in the rabbit's brain.
Human herpesvirus type 1, also called herpes simplex viruses type 1 (HSV-1), is a common sexually transmitted disease (STD) in people. It can cause oral, genital and ocular (eye) lesions. Humans are the primary host of this virus, but it has been found in species such as rabbits, rats, mice and chinchillas. In rabbits, it usually causes encephalitis, and is almost always fatal for these animals.
This case shows how viruses typically associated with one species can sometimes affect others. While we usually focus on microorganisms moving from animals to humans, they can also move in the opposite direction, as was presumably the case here. Close face-to-face contact with the infected owner was probably the source of the virus. This is an example of an uncommon event, but one that should not be ignored.
If you have an active herpesvirus infection:
- Limit close contact with rabbits (and, to be on the safe side, probably restrict contact with other pets as well). In particular, avoid contact with the mouth, nose or eyes.
- Wash your hands or use an alcohol hand sanitizer regularly, particularly after using the washroom or having any contact with infected sites/sores.
- Make sure herpesvirus infection is considered if your rabbit develops eye or neurological disease.
The risk of rabbits transmitting human herpesvirus is completely unclear. Common sense dictates that anyone hanlding a potentially infected rabbit should restrict contact with the eyes/mouth/nose, wear gloves, wash hands after contact (even if gloves were worn) and avoid contamination of clothing.
Rabies vaccine access exceptions
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In Canada, access to rabies vaccine for animals is restricted to veterinarians (i.e. only vets can buy the product itself and administer it to people's animals). In general, this is an excellent approach because it ensures that the vaccine has been handled and stored appropriately, animals have been vaccinated properly and accurate vaccination records are kept. I certainly wouldn't want rabies vaccine freely available, whereby anyone could buy vaccine, handle it poorly, vaccinate their animal improperly, and yet believe or claim to have a properly vaccinated pet.
The problem with this restriction is the fact that veterinary care is not always available. Specifically, I'm referring remote northern communities that do not have veterinary care on a regular or even a sporadic basis. I received an e-mail the other day from a medical professional in a fly-in First Nations community in Northern Ontario. They have not had a visit from a vet in a while, so the dogs there aren't vaccinated. Unfortunately, a dog was attacked by a wolf recently so it must be considered possibly exposed to rabies, resulting in euthanasia or long quarantine. The question was about what can be done in those communities to provide rabies vaccine for people's animals. I didn't know, so I inquired with the Canadian Food Inspection Agency, the federal agency in charge of all-things-rabies.
There are actually provisions in Canadian regulations for situations like this (a provision in the Health of Animals Regulations Section 132.4 (2), if you want to know specifically). This allows rabies vaccine to be sold in accordance with written permission granted by the Minister, in specific circumstances such as in a remote area where veterinary services are not readily available. The provincial veterinary association is typically contacted to determine whether or not there is a veterinarian who could arrange to do the vaccinations. If the provincial association agrees that there is no veterinary service available to the community, then permission can be granted to purchase vaccine.
It's quite a reasonable and logical approach that allows for access to rabies vaccine when needed, but has enough controls in place to ensure that this can't lead to abuse of the exception. People in remote communities in Canada should be aware of this. Some communities get periodic visits from vets but there are many others such as the one in this case that don't have any direct access to veterinary care, and this is a way of at least providing protection for people and pets against rabies.
Antibiotic use compliance
In an interview with the San Francisco Chronicle, veterinary dermatologist Dr. George Doering makes a pretty obvious but very important comment that is worth repeating:
"The biggest problem we have in almost all the fields of veterinary medicine is compliance. You say to a client, "This dog needs to take this antibiotic twice a day." Well, the reality is we might be lucky if they get it once a day. ...They don't want to accept the seriousness of the problem."
This very true and very important. Compliance with recommended antibiotic therapy is probably a major factor in treatment failure, recurrent infection and antibiotic resistance. Antibiotic dosing regimens are specifically designed to ensure that the right concentration of drug is present in the body for the appropriate time. Missing doses, skipping days, not making sure the animal actually ingests the drug, and other problems that result in the pet not getting what is was supposed to get are very important.
It's easy to understand why this happens, because administering antibiotics (particularly to some difficult-to-pill dogs and cats who can smell the medication when it comes in the house!) can be a hassle. Because of this (and the very natural human tendency to take the easy way out), it's really important for people to understand the concerns about inadequate antibiotic administration and what they need to do.
- Follow the entire treatment course. You should have no antibiotic left at the end of the recommended treatment time.
- Make sure your pet actually swallows the antibiotic. If you add pills to food, make sure you check to see that the pill isn't left behind. It's amazing how animals can eat a big bowl of food and leave behind a little pill. The picture shows how my dog Meg can, in the process of inhaling her food at an incredible rate, leave behind a tiny ephedrine pill.
- If your pet will not eat the drug voluntarily, talk to your vet about other ways to administer it, such as compounded in chewable treats. Depending on you and your pet, opening your pet's mouth and placing the pill at the back of the tongue may be an option. Talk to your vet about this first and make sure you wash your hands after. If you think there is a risk you might be bitten, if you are at high-risk for infection because you are immunocompromised, elderly or pregnant, don't try to "pill" an animal in this manner.
- If you still can't get the drug into your pet, talk to your vet right away. If you wait a couple of days or a week or more to tell your vet, your pet may be even sicker by then. There may be other options to oral drugs such as injectable antibiotics. This might end up being more expensive or difficult (e.g. you may have to take your pet to the vet every day for its medication), but it will be better for your pet and may even save you money in the long run by ensuring the infection is properly and completely treated the first time.
- Never stop treatment because your pet looks better. Often, signs of infection get better before the bacterium is completely eliminated. Stopping too soon allows the bacterium to regrow, potentially as a more resistant form.
- If you are supposed to take your pet to the vet for a recheck at the end of treatment, then do so. Sometimes longer courses of antibiotics may be needed, and it's much better to continue the current treatment course than to have to start again a couple weeks down the road when the infection has returned (sometimes with a vengeance).
- If in doubt about anything, call your veterinarian. He or she is there to help, and wants your pet to get the best treatment possible.
MRSA and atopy
A recent question: "If a dog has severe atopy that is poorly managed, and is colonized w/ MRSA (superficial dermatidis on neck ventrum and axilla) are repeat infections w/ MRSA likely, if the allergies cannot be controlled?"
Dogs with atopy (allergic skin disease) are prone to opportunistic infections because of the abnormal skin "environment" and trauma from licking and scratching. Damage to the skin creates the opportunity for various bacteria to cause infections, including some bacteria that may usually live on normal skin without causing problems. Most commonly, staphylococci are involved, and this may include skin infections with MRSA (methicillin-resistant Staphylococcus aureus). The likelihood that a dog will develop an MRSA skin infection depends on the likelihood of exposure to MRSA. If the dog is already a carrier (i.e. has MRSA in its nose or intestinal tract), the odds are greater because exposure of the skin to the bacterium is more likely. If the dog is owned by someone with MRSA or someone who visits human hospitals, the risks are likely greater as well because of the increased chance of MRSA exposure via the owner.
For most dogs, the risk of MRSA infection is not high. Fortunately, dogs that are MRSA carriers are typically only carriers for a short period of time. They usually eliminate MRSA carriage naturally within a couple weeks, if re-infection is prevented. So, for a dog that is a carrier or has an MRSA skin infection, if carriage is eliminated and the infection is properly treated, the risk of subsequent MRSA infections should be quite low, as long as there is a not a high likelihood of re-exposure.
Dogs with chronic skin disease should not visit human hospitals in order to reduce the risk of developing MRSA infection. If such a dog is owned by someone who is infected or colonized with MRSA, particular attention should be paid to handwashing to reduce the risk of transmission of MRSA to the dog. In situations other than these, recurrent MRSA infection is probably not a risk if basic hygiene practices are used. If an MRSA infection is present, it must be properly treated - sometimes apparently "repeated" infections are actually infections that were never completely eliminated in the first place. A key component of management of dogs with atopy (and other chronic skin conditions) is getting the atopy under control so that there is less chance of secondary bacterial infection.
More information about MRSA in pets can be found on the Worms & Germs Resources page.
Tularemia in cats and dogs in Sioux Falls
Tularemia has been diagnosed in five dogs and cats in Sioux Falls, South Dakota. At least one of the pets has died. Tularemia, sometimes referred to as "rabbit fever" is caused by the bacterium Francisella tularensis. Infections occur throughout much of the Northern Hemisphere but are much more common in certain regions, such as the central US. This bacterium has received a lot more attention over the past decade because of its potential use as a bioterrorism agent, but infections have been occurring in people and pets for a long time. In North America, the cottontail rabbit, wild hares and some rodents are the main reservoirs. People and other animals get infected through close contact with infected animals (e.g. rabbit hunting) or through bites from blood-feeding insects.
There was no mention of human cases in the recent report from South Dakota. One of the implications of identifying this disease in pets is that whatever infected the pet could also be a risk for people. If the pets were infected by contact with wild animals, people with similar contact with wild animals could also be exposed. If there is no chance the animals had contact with infected wildlife, then insect-transmission is most likely, and the same could happen to human members of the household (or elsewhere in the area). Therefore, diagnosis of tularemia in a person or pet should put both veterinarians and physicians on the lookout for further cases in all species.
Transmission of tularemia from infected pets to humans is also a concern. This has been reported in numerous instances, most often with cats. There are published reports of transmission from dogs to humans, but these are less convincing than the numerous cat-to-human reports. There's also a report of tularemia transmission from a hamster to a child. The overall risk of transmission is probably low, but tularemia can be spread from pets to people by scratches, bites, and perhaps regular close contact.
You can reduce the risk of your pet being exposed to tularemia by:
- Keeping pets indoors as much as possible. Cats should stay indoors. Dogs should not have uncontrolled outdoor access.
- Dogs should not be allowed to hunt rabbits in areas where tularemia is endemic.
- Animals that venture outside should be checked regularly for ticks and a preventive medicine program for ticks should be in place.
- Routine measures to reduce bites and scratches from dogs and cats should be taken.
Giardia and high-risk households
Giardia is a relatively common protozoal parasite that can cause diarrhea in people and dogs (among other species). It can also be present in healthy pets, with most studies reporting Giardia shedding in approximately 7% of healthy dogs. While recent research indicates that a large percentage of dogs with Giardia carry types that do not infect people, this parasite is still a concern, particularly in households high-risk households with immunocompromised individuals, very young children and elderly persons.
What do I do if I'm in a high-risk household and my dog is diagnosed with Giardia?
- Genotyping of Giardia from the dog to see if it is a strain that affects humans would be ideal, but this is not readily available outside research labs. Maybe in the future this will become a standard test.
- The dog should be treated according to your veterinarian's instructions. The entire treatment course must be completed.
- All other dogs and cats in the house should be treated at the same time, even if they have been tested and were negative, because we want to avoid "cycling" of Giardia between the pets.
- All animals should be bathed on the first and last day of treatment to reduce the risk of re-infection from Giardia cysts on the fur. This should not be performed by high-risk individuals, and is probably best done at a veterinary clinic or groomer to reduce bathroom contamination, if bathing can't be done outside.
- All animals should be tested after treatment to ensure the infection has been eliminated. This is usually done about 5 days after the last treatment. If antigen testing is used, some animals will still have positive results 5 days after treatment because of dead Giardia still working their way out, in which case re-testing at around day 21 post-tretament is recommended.
- Care should be taken to avoid direct and indirect contact with feces. Close attention to handwashing promptly after cleaning up feces or fecal-contaminated areas is very important. Regular handwashing after contact with pets is always important.
Horse ownership and tetanus exposure
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 very rarely because of vaccination and because people have lower susceptibility to the disease. While we pay a lot of attention to tetanus in horses, this does not mean that being around horses increases a person's likelihood of exposure to tetanus. The bacterium that causes tetanus, Clostridium tetani, lives in soil and commonly present in the environment. The more environmental exposure that you have (especially to soil), the greater your risk of exposure to C. tetani. 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 prevention. 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 get booster shots on schedule, and often only receive them when they have had a wound that requires medical care. For example, If you get stitches, the medical staff 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 (or if you can't remember).
More information about tetanus in horses is available on the equIDblog Resources page.
This Worms & Germs blog entry was originally posted on our sister site, equIDblog, on 10-Jul-09.
Traveling parasite roadshow
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 fully funded by the pharmaceutical industry. That doesn't necessarily mean that CAPC's educational efforts are suspect - people participating with their roadshow have solid credentials, but you do have to critique some of the things CAPC says.
One news article about CAPC's efforts states 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, meaning 14 percent of the population has antibodies against Toxocara. The presence of antibodies means that at some point in life the person's (or animal's) body was exposed to Toxocara and produced antibodies. It does not mean that these people were ever sick and it certainly does not mean that these people are currently infected. Toxocara can cause serious infections and is a concern in some regions (although it's extremely rare in Ontario), so it warrants some attention, but we need 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 of dogs and cats in all regions. Statements like this weaken the other good educational information CAPC has, 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 the information, and don't be afraid to ask for facts, or to get information from other sources.
For more information about deworming recommendations for dogs and cats in Canada, see this previous Worms & Germs post.
Cats and Q-fever
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 - 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 also been many reports of Q-fever associated with cats, also mainly through contact with these animals around the time they give birth. Cats may be the most important Q-fever reservoir in urban areas.
The study I was reading, a 1988 article from the journal Chest, describes a Q-fever outbreak in a town in Nova Scotia. Thirty-three people were infected in the town of Baddeck (population 900, meaning 2.8% of the population was affected). Forty-two percent of infected individuals lived in four side-by-side buildings. Investigation revealed that most infected people 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 the four 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 even be spread through the air through aerosols (e.g.dust, tiny droplets of fluid), direct contact (e.g actually touching the cat) is not required for infection to occur.
That being said, cat-associated Q-fever is probably still pretty uncommon, but Q-fever can be a very serious disease. Since transmission mostly involves cats at the time of birthing, 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 area 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 birth fluids is likely to occur, gloves should be worn. Hands should be washed after gloves are removed.
- If a cat gives birth inside, the area should be thoroughly cleaned and disinfected afterwards. 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.
More information about Q-fever can be found in the Worms & Germs archives.
Dogs and swimming pools
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 this an infectious disease risk?"
The honest answer is we don't really know. The reasonable answer is the risks are pretty low, especially when a little common sense is exercised. You are probably more likely to get a pool-associated infection from another person than a dog, although 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 associated with letting the pooch go for a dip in the pool, 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 further. 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. However, some pathogens can survive for days in a pool, 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 for transmitting disease. 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
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, and he was bitten in the process. The kitten then proceeded to bite the boy's 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 three bitten people are now undergoing post-exposure treatment. Animal control is handing out flyers in the neighbourhood to warn others, as there may be more rabid animals in the area. One particular concern with young kittens is that sometimes multiple animals from the litter are infected, so 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 by a stray or wild animal, call animal control to catch it. If you can safely contain it (e.g. lock it in a garage) without putting other people at risk, do so and then wait for animal control to capture the animal.
- Vaccinate your pets.
