1. Consuming a commercial or homemade raw diet, a homemade cooked diet, or raw meat and eggs, increases a pet dog’s risk of carrying Salmonella.

Raw is raw, and by now we're hoping that people are getting the message that raw is contaminated, whether we're talking about a commercial or homemade raw diet, or feeding any raw animal products (e.g. meat, eggs).  The fact that homemade cooked diets also made the list could be explained by the fact that in order to make such a diet, owners still need to start with the raw ingredients.  Handling and cooking raw meat and animal products for your pet should be done with the same precautions as handling and cooking raw meat for yourself or your family.  If these homemade diets were not cooked as thoroughly as they should have been, or if there was contamination of the dog's dishes with raw product, that could explain the association with Salmonella shedding.  Although traditional commercial diets can also be contaminated with pathogens (usually after processing), the risk with these is much lower.

2. Testing multiple consecutive whole fecal samples greatly improves Salmonella recovery in dogs.

This is no great surprise either.  Dogs (and many other species) shed Salmonella intermittently, so not every fecal sample from a Salmonella-positive dog is going to yield Salmonella on culture.  The authors tested five daily fecal samples from each dog.  Based on this study, the sensitivity of testing a single fecal sample in a dog (i.e. the likelihood that a Salmonella-positive dog will test positive on one fecal sample) was only 35.5%.  That means almost two-thirds of positive dogs will be missed if they're only tested once.  The take-home message on this point is that in order to find Salmonella in a healthy pet dog, multiple samples should be tested.

3. Having multiple dogs in a household, using probiotics and contact with livestock are important potential risk factors that need to be investigated further.

These were factors that were flagged by the authors for future investigation, because at first they seemed to be associated with Salmonella shedding in the dogs, but when the feeding of raw diets was taken into account the associations were no longer significant.  A larger study, or one using a different design, will be needed to help tease apart the potential effects of these factors from feeding practices.

The bottom line: Feeding raw is risky business.  Some people swear by the benefits of raw diets, but the objective evidence is lacking.  There is clear evidence of the risks.  In my mind, the potential up-side simply cannot outweigh the well-established down-side of feeding raw diets to pets.

The researchers collected feces from 52 active raccoon latrines around the city and from 114 "nuisance" raccoons that were caught, euthanised and submitted for necropsy to the local lab. Interestingly, the vast majority of latrines and nuissance raccoons were found close to the two major rivers that run through Winnipeg. Half (50%) of all the latrines were positive for roundworm eggs on at least one sample (out of a possible 3). Among the necropsied raccoons, 61/114 (53.5%) were positive for roundworms. Adult raccoons were almost four times as likely to carry roundworms than juveniles (which is in contrast to a previous study that found juveniles more likely to be infected), and bigger raccoons (over 2.75 kg) were more than seven times as likely to carry roundworms compared to smaller animals. Although there are regions where the prevalence of B. procyonis s reported to be very low, Winnipeg, like many other regions of North America, has joined the ranks of those where the prevalence is high and the public needs to be aware of the associated risks.

The most severe zoonotic disease caused by B. procyonis is called neural larval migrans (NLM), which results from migration of parasite larvae through the central nervous system (i.e. brain). Two of the reasons this is much more of a concern with raccoon roundworms (Baylisascaris) compared to dog and cat roundworms (Toxocara) are:

1) A massive number of parasite eggs are passed in the feces of infected raccoons (which typically have a very high burden of adult worms). Coupled with the fact that the eggs are further concentrated in areas where many raccoons defecate (latrines), this can lead to heavy exposure of people (or animals) who come in contact with the soil in these areas, which greatly increases the risk of infection.

2) The larvae of B. procyonis are very active migrators, and they get bigger as they migrate through tissues - much bigger than Toxocara larvae ever get, which means they also tend to cause a lot more damage before they're finally (if ever) trapped or killed by the body's immune response.

Natural infection of dogs living in the same areas as raccoons has been found - it's not common, but it appears to occur frequently enough to warrant noting. Dogs and cats can also be infected by their own species of roundworms, which will also result in parasite eggs being shed in the feces. It's important to have your veterinarian perform a fecal examination for your pet on a regular basis so any parasite infestations (roundworm or other) can be treated.

Dogs and cats may also be susceptible to larval migrans in the same manner as people (and the animals at the zoo in Winnipeg) if they are exposed to high numbers of infectious eggs. Remember that roundworm eggs must be swallowed in order for infection of any kind to occur, so good hand hygiene and avoiding soil contamination of food are key to preventing transmission. Also, do not allow your pet to dig or play in an area where raccoons defecate (preventing direct contact between your dog and raccoons should go without saying!).  And of course, feces of any kind (and from any species) should be treated as infectious material, and handled with appropriate precautions.

More information about Baylisascaris and raccoon latrines is available in our archives.

Anyone who has read anything about food safety hopefully knows that raw meat can potentially be (and usually is) contaminated with many different pathogens - that's the biggest reason why observing proper cooking times and temperatures is so important.  Raw poultry in particular should basically be treated like it's contaminated with Salmonella and/or Campylobacter until proven otherwise.  You can just imagine the field day that these bacteria could have in a nice warm, wet bathtub - it's just the way they like it, and it's exactly what we try to avoid in the kitchen, where food is ideally kept either nice and cold or nice and hot in order to prevent (or at least minimize) bacterial growth.  Then of all things to put young children in this veritable cesspool of bacteria - turkey and all - it's just a gastrointestinal disaster waiting to happen.  You also needs to consider what the turkey could become contaminated with sitting in bathwater.  Even children who don't have diarrhea can be shedding intestinal pathogens - human pathogens which are obviously transmissible to other people.  If you really cooked that bird well (maybe deep-fried it) I suppose that should ultimatley eliminate any surface contamination anyway, but I don't think I'd be able to get past the "ick" factor.  Don't throw the baby out with the bathwater, but of there's a turkey in there (as far as I'm concerned) that can go.

I realize this is primarily a food safety issue, but it made me think about what else this person (or others) may put in a bathtub.  In previous posts in which we've talked about reptiles kept as pets (all of which should be treated as Salmonella carriers), we've mentioned that ideally (if they need a bath) they should be bathed in their own designated container (like a big rubbermaid) and not in the bathtub.  If there is no other option and the bathtub must be used, it should be thoroughly cleaned and properly disinfected (keeping contact-time with the disinfectant in mind) before it is used again by a person (especially children). 

Ideally the same precautions should be taken if you bathe a dog in the bathtub, but the risks are not as high as with reptiles (unless the dog is very dirty, has skin lesions, or has (or recently had) diarrhea).  We've talked about the limited risks of allowing dogs in backyard swimming pools (but of course there is even less chlorine in bath water).  I hope no one ever bathes their dog with their kids - we could debate the risks, which likely aren't high anyway, but in the end the risk is simply unnecessary.  The pool is one thing, but there's no reason for a dog to be in the tub at the same time as the kids (and really, how clean are the kids going to get with a dirty dog in the tub?).  If you're trying to save water you can always throw the dog in after the kids are out.

If you're attempting to bathe a cat in the tub... well, based on most feline behaviour I'd say your primary risks are bites and scratches more than enteric bacteria and parasites.  Proceed at your own risk!

A happy (and hopefully healthy) American Thanksgiving to all of our US readers!

Responsible use of antibiotics can help stop resistant bacteria from developing and help keep antibiotics effective for the use of future generations.  Successful national public awareness campaigns are already resulting in more rational use of antibiotics and a reduction in levels of antibiotic resistance in Europe.

Responsible use of antibiotics includes use in people and in animals.  Here are some of the things you can do to help with regard to antibiotic use in your pets:

• Only give your pet antibiotics if directed to do so by your veterinarian.
• Make sure your pet gets the full dose of medication at the correct time(s) of day.  If you are having problems getting your pet to swallow pills or take medication, contact your veterinarian as soon as possible.  Your veterinarian may be able to give you advice on some "tricks" for getting your pet to take the medication, or sometimes the medication can be provided in a different form (e.g. a liquid instead of a pill).
• Always ensure your pet finishes the entire prescription.  There should be no leftover pills or medication.  Do not stop giving your pet the antibiotics just because it looks/acts like its feeling better.  This is a common mistake that can have disasterous consequences!  You should NEVER "save a few pills for the next time."
• Never give your pet antibiotics that were prescribed for you or any other person, whether they are expired or not.

This is not a reason to panic.  No one can get the flu from eating a properly-cooked Thanksgiving turkey (nor from any other type of properly-cooked turkey).  The producer has voluntarily (and very responsibly) quarantined the affected flock, and no birds or eggs have left the facility.  There is no risk to the food chain.

Pigs can be infected by human, pig and bird flu viruses, and multiple infections can result in viruses trading genes and producing new viruses that can infect more species.  So it's not too surprising that H1N1can infect people, pigs and now birds as well.  This incident serves as an important reminder that we need to remain diligent about infection control and hygiene, even around animals.  It's highly unlikely that these turkeys had contact with infected pigs - most likely the virus was spread to this flock by a person.  Poultry producers may therefore need to consider getting vaccinated for H1N1 flu not only to protect themselves, but also their flocks, and anyone who may have the flu should definitely stay off these farms.  Hopefully the virus does not become established in wild bird populations (like H5N1 has in some areas), as this would make it much harder to control.

Recommendations for avoiding the flu (H1N1 or other) remain the same:

• Wash your hands and/or use alcohol-based hand sanitizer
• Sneeze into your elbow
• Disinfect commonly touched surfaces
• Stay home if you are sick
• Get vaccinated!

Prevention of lepto in dogs, as with most diseases, is preferred to trying to treat sick animals.  The best way to avoid the bacterium is to keep your dog out of areas where infected wildlife may urinate frequently, particularly out in the bush.  But of course, skunks and raccoons can be found as close as the backyard as well, so even in the city the risk isn't zero.

If your dog does frequently go into the bush and is at increased risk for leptospirosis, hopefully you've already discussed vaccination with your veterinarian.  While the vaccine available doesn't protect against all types of lepto, it does help protect against the most common ones - in Ontario, these are believed to be the lepto serovars grippotyphosa and pomona.  We also received the following question from a reader the other day:

"Should a dog who has shown positive for early stages of kidney disease be vaccinated against leptospirosis?  Can the vaccine accelerate the illness to acute renal failure?"

I can see where the question comes from, but the simple answer to the second part of the question is no.  Although the infection can certainly affect the animal's renal function (and can push even healthy dogs into renal failure if it is severe), the vaccine works on the dog's immune system and does not affect the kidneys directly.  The answer to the first part of the question is, of course, much more complicated, and depends on many other factors including the dog's overall health status, lifestyle and other risk factors, and vaccination history.  The decision about whether or not to vaccinate your dog should be discussed on an individual basis with your veterinarian.

More information about leptospirosis is available on the Worms & Germs Resources page and in our archives.

Image: Scanning electron micrograph of Leptospira sp. bacteria (source: CDC Public Health Image Library ID#138))

Q fever is caused by a highly infectious organism called Coxiella burnetii.  The organism can be carried by many different animals, but particular sheep and goats, and sometimes cattle.  Most of the time it does not cause a problem in these species, but it has been linked to abortions and abortion storms (i.e. when many animals in the herd abort in a short period of time).  It can be shed in manure, urine and milk, but the largest numbers of organisms are found in birth fluids and tissues (e.g. aborted fetuses, placentae).  When the tissues and fluid dry out, the organism can be stirred up into the air over short distances in dust.  Humans are highly susceptible to C. burnetii, and inhaling even a single organism can cause infection.  Most of the time people who get sick have signs very similar to the flu, but severe pneumonia and liver disease can develop in a small number of cases.

A definitive link between sheep and goats and the Q fever outbreak in people in the Netherlands has not yet been established, but it is highly suspected that many of the cases are associated with infected goats (and some sheep).  In the last two years numerous outbreaks of Q fever have been reported on dairy goat farms and one dairy sheep farm in the Netherlands.  This has lead to a cooperative arrangement between the Dutch agricultural ministry and the Dutch public health ministry - these two goverment branches have come together to help cover the costs of vaccinating sheep and goat herds in the country, in order to help stem the tide of disease and ultimately prevent more human cases.  This is a great example of the "one medicine" concept, whereby groups on both the human health and agricultural/animal health sides are working together on this problem.

Manditory vacciation is now required for sheep and goats on larger farms in the hardest-hit areas, as well as any farms reporting any cases of Q fever since 2005, and any sheep or goats that have a "public function" (e.g. petting zoo animals or occupational therapy farms).  It is very important that this last group is included under the manditory vaccination, as these animals have a large amount of contact with people.  Steps have also been taken to improve hygiene, restrict spreading manure from sheep and goats, restrict visitors to infected farms, and to make abortion storms on sheep and goat farms reportable, so they can be investigated for Q fever.  It will be interesting to see how effective these measures are at controling the outbreak in 2009.

More information on Q fever can be found in our archives.

A couple of months back, Oprah adopted two cocker spaniel puppies from a shelter in Chicago. Unfortunately, within two weeks they both came down with parvovirus infection and had to be hospitalized. I'm sure both dogs received top-of-the-line care with no expense spared, but even so one of the puppies died. The other puppy came very close to dying as well, but happily she apparently has now recovered completely and is doing just fine (or quite likely better than fine, considering who her new owner is!).

Oprah also mentioned how one of her other dogs, Solomon, also suffered from a parvo infection years ago, but that dog was over a year old when he became ill. It's actually quite unusual for any dog to get parvo beyond one year of age - most adult dogs are not affected by the virus, unless perhaps their immune system is compromised for some reason.

These stories bring up a few interesting points to ponder:

It's great to adopt an animal from a shelter and give a homeless animal a home. It is an act of great kindness that I don't want to take anything away from in the least. However, it's important to realize that you never know what shelter dogs may be carrying, nor how well vaccinated they are.

• Even if the animals are vaccinated once at the shelter, the protective effect may be less than ideal if a properly timed vaccination series is not completed.
• In this case the pups may have been exposed to parvo after leaving the shelter, but they could have just as easily been exposed at the shelter, which begs the question of what else might they have been carrying? Bacterial pathogens such as Salmonella and Campylobacter are also particularly common in young dogs and cats (even healthy ones), and these are potentially zoonotic agents.

Young animals, particularly from shelters, are higher risk in terms of the infectious diseases they can carry and transmit. That doesn't mean they shouldn't be adopted, but it does mean taking some extra precautions for the first several weeks they're in their new home. These include being very diligent about controlling stool contamination of any kind (which can be easier said than done during the house-training phase), preventing contact with high-risk individuals (e.g. young children, the elderly, anyone with a weakened immune system) and lots of handwashing on the part of everyone involved with the puppy (or kitten!).

Parvo is a very serious disease in puppies, yet people sometimes become a little complacent about vaccinating for parvo and other puppyhood diseases.   Remember, though, that the reason parvo has become so much less common than it used to be is largely because of widespread and effective vaccination.  I have to wonder about how well vaccinated Oprah's dog Solomon was to get the disease at the age he did, but there could easily be other factors involved as well.  The virus is still out there, and if we become lax in our infection control practices - including decreasing exposure of puppies to the stool of other dogs, as well as vaccination - it's waiting in the wings for its opportunity to move in. Even with the very best care the infection can still be fatal.

It's also relevant to note that, as demonstrated by Solomon's case, just because parvo is very uncommon in adult dogs doesn't mean it's impossible for them to get it.  It's important to always remain diligent.

Parvoviruses are quite species specific, so thankfully people cannot get parvovirus from dogs, but remember that puppies can get diarrhea from pathogens like Salmonella, which can be transmitted to people. There is also a human parvovirus which is the cause of Fifth disease. Just like the dog virus cannot infect people, the human virus cannot infect dogs.

Image source: http://omg.yahoo.com

• Almost all foals are exposed to R. equi as neonates, but most of them never develop signs of infection.
• Giving newborn foals hyperimmune plasma (plasma with extra antibodies against R. equi) may have some beneficial effects on farms where the infection is a recurrent problem, but this practice is still controversial.
• Adult horses are essentially immune to the infection.
• In almost all cases if clinical disease in foals, the R. equi strain involved carries a special gene called vapA.
• Mortality rates in foals vary considerably from 0% to 30%.
• So far, efforts to develop a vaccine to help protect foals have been unsuccessful, but research in this area is ongoing.

People can also be infected with R. equi, and as in foals, pyogranulomatous pneumonia (infection of the lungs which results in the formation of many abscesses) is one of the most common conditions caused by this organism. However, there are a few important differences between infection in people and infection in horses:

• 85% to 90% of people with R. equi infection are immunocompromised, meaning their immune system is weakened or suppressed for some reason, e.g. HIV infection, or immunosuppressive drugs taken by organ transplant or cancer patients.
• Among people infected with R. equi who have normal immune systems (i.e. immunocompetent), about half of the infections are localized, meaning they only affect one small part of the body. Many of these are associated with wound infections.
• Only 20% to 25% of the R. equi isolates in people carry the vapA gene.
• Infection in immunocompetent people can be fatal in approximately 11% of cases, but among HIV-infected patients the mortality rate from R. equi infection can be as high as 50% to 55%.

Rhodococcus equi is actually a soil organism, and this is likely the most common source of the organism for both horses and people. Only approximately 1/3 of humans infected with R. equi report that they have had contact with horses or pigs (pigs can also carry the bacterium). So we don't know how much of a risk an infected foal is to a person.  However, it is prudent for people, particularly those with weakened immune systems, to take precautions to avoid potential transmission of R. equi from horses.

• Try to reduce dust levels on the farm. Because R. equi most often lives in the soil, it can get stirred up into the air in dusty areas, which can then lead to inhalation by animals and people. Doing things like planting grass or other vegetation, installing windbreaks in high-traffic areas, or wetting down dusty stalls or paddocks can help reduce dust levels in the air.
• Keep open wounds and other broken skin covered when working around animals.
• Always wash your hands after handling a foal (or any horse)
• If you have a foal that develops signs of R. equi infection, make sure you have your veterinarian examine it as soon as possible so the diagnosis can be determined and the foal can be treated properly as soon as possible. Some foals with R. equi may develop severe pneumonia very quickly, so it’s important that they are examined right away.

"...What if veggies get infected with raccoon stool[?] Can eggs be killed after [the] veggie is grown and ready to eat?"

Great question.  The concern in the case of raccoon stool is the eggs of the roundworm Baylisascaris procyonis, which can be passed in huge numbers by a relatively high percentage of raccoons in many regions.  If swallowed, the eggs release larvae which can migrate through the tissues of the body, rarely causing visceral, ocular or neural larval migrans.

The good news:

• Raccoons like to defecate in the same areas most of the time, usually on a relatively flat, elevated surface (e.g. woodpile).  These areas become raccoon "latrines", and the soil in the area can become very heavily contaminated with roundworm eggs.  The good part is that most raccoons therefore not defecate in your garden.
• Vegetables cannot become "infected" by the parasite - the eggs cannot be absorbed or otherwise get inside a vegetable, they can only contaminate the parts of the plant that are directly in contact with soil.

The bad news:

• Even though raccoons may not poop in your garden, they can still track roundworm eggs into the soil on their fur or paws when they come by to explore your crop, so you should always consider soil outside as potentially contaminated.
• Baylisascaris eggs are highly resistant to disinfectants and chemicals, so they can't be killed this way.
• Raccoon roundworms aren't the only parasites that may be found in garden soil.  Dogs and cats can carry other roundworms (Toxocara spp.) which are also capable of causing larval migrans if swallowed (although infection with these worms in dogs and cats is not nearly as common as infection with Baylisascaris in raccoons).  Cats in particular, unfortunately, do sometimes like digging in gardens and may sometimes use a garden as a litterbox.
• Soil, particularly if it's contaminated by the stool of any animal, can also contain many different kinds of bacteria such as Salmonella.  Even if you can somehow protect your garden plot from animals, purchased garden soil and fertilizers may contain or may have come in contact with animal stool somewhere along the way.

So how do you make your garden veggies safe to eat?

• Wash wash wash: Because Baylisascaris eggs are so difficult to kill, the best thing to do is physically remove them from all surfaces of your vegetables by washing thoroughly to remove all visible dirt before doing anything else.  If you cut into a vegetable before washing it, the soil on the outside can contaminate the inside.
• Peel peel: Peeling vegetables ensures that all dirt (including any dirt stuck in tiny crevices on the vegetable's surface, or dirt you may not be able to see with the naked eye) is removed prior to consumption, but it's still crucial to wash the veggie first (and your hands) before peeling.
• Cook: From an infection control perspective, it's best to cook vegetables before eating them.  This actually won't do anything to Baylisascaris eggs - these have to be removed by washing and peeling - but it does help kill bacteria that either contaminated the veggies out in the garden or that contaminated the veggies during their preparation in the kitchen.  For those of us who like our nice crunchy vegetables, obviously cooking them won't do, therefore washing and peeling become that much more important.

And, of course, always wash your hands thoroughly with soap and water after you've been working in the garden, even if you wear gloves.

In a lot of urban areas, it's hard to prevent raccoons and other animals from getting into yards and gardens.  There are things you can do to discourage raccoons from hanging around your house, and if raccoons establish a latrine on your property it must be very carefully cleaned up.  For more information on Baylisacsaris, raccoons and cleaning up raccoon latrines, please see our archives.

Everyone involved in Worms & Germs would like to take this opportunity to thank all the visitors who come to our site, and especially those who keep coming back for more! Please continue to help us spread the word about zoonotic disease control and safe, responsible pet ownership. Questions, comments and suggestions are always welcome!  -Scott & Maureen
                                         

There's a distinct lack of information about where this strain of the influenza virus actually came from.  I heard on the news this morning that one person who was interviewed by a CNN reporter was even trying to blame Canada for the outbreak, claiming that it was Canadian tourists that introduced the disease to Mexico in the first place!  While I'm sure there will eventually be a great deal of investigation into how the outbreak got started (for the moment I think everyone's more worried about trying to just keep it under control), it's quite possible that we'll never find the "index case" or know exactly from where it came.  But one thing's for sure: somewhere along the way, there has to be some pigs involved.

Pigs are the great "mixing pot" of influenza viruses, particularly with regard to avian, human and swine versions of the pathogen.  Pigs can be infected by strains of all these different types, and coinfections (infection with more than one influenza virus at the same time) provide the viruses with a prime opportunity to trade RNA and recombine to form new influenza strains with new properties - more infectious, more virulent, or perhaps better able to infect another species, for example.  In this case we appear to have a swine influenza virus that is not only capable of being spread to people (as occasionally happens with "regular" swine influenza viruses), but also between people, and hence the developing human outbreak.

But what about the pigs?  There isn't a lot of information out there at the moment, with all the focus on the human aspect, but so far Mexican authorities have found no infected pigs in Mexico (at least no where they've looked - so far).   Influenza in pigs is really nothing new, and other swine influenza strains are commonly found in pigs around the world.  Highly pathogenic strains, like those that cause massive devastation of poultry flocks, don't occur in swine.  If an influenza virus gets into a pig barn, however, it's like putting a person with the flu in a crowded room - the virus spreads very quickly through the air over short distances and soon everyone (or every pig) has the flu.  Thankfully the virus generally also moves on quite quickly, and after a few days the animals generally start to recover.  While such an outbreak certainly affects their growth efficiency, very few (if any) pigs die.

Yesterday the Canadian Veterinary Medical Association (CVMA) distributed a fact sheet on swine flu from the Canadian Food Inspection Agency (CFIA) for all Canadian veterinarians and swine producers.  The CFIA is encouraging increased vigilance with regard to monitoring and diagnosing disease in Canadian pigs, to prevent the disease from spreading through the swine population.  In addition to emphasizing vaccination, good hygiene practices and biosecurity, particularly around sick pigs, they also point out that it's equally important (especially now) for anyone who may have the flu to avoid contact with pigs (be they Canadian pigs or pigs in any other country), in order to avoid spreading the virus to them.  Hopefully people in other countries will take the same precautions.

Another very important point is that swine influenza is NOT a food safety concern.  The virus does not survive well in the environment for very long, and therefore cannot survive on pork products, and certainly cannot survive proper cooking (which is always very important for any kind of meat).  The fact that some countries are banning pork imports is really not going to do anything to help control the outbreak - the concern should only be about live pigs (and people).  So you can still have pork sausages at your next spring barbeque, just ask anyone who's feeling "under the weather" (or a little flu-ish) to please stay home!!

The big worry with influenza viruses is that they have a high propensity to "mutate" - sometimes they change slowly (i.e. antigenic drift), and sometimes they change quickly (i.e. antigenic shift).  When two different influenza viruses infect the same animal or person, the different components of each virus can recombine to make a new virus that will share some characteristics of both the original viruses.  For example, if a highly pathogenic avian influenza virus (like the H5N1 virus from Asia) were to recombine with a human influenza virus, it could create a virus that causes severe disease like the avian virus, but which can be readily transmitted between people. This would  create the potential for a serious outbreak of severe, even fatal illness in people.

Highly pathogenic avian influenza of either the H5 of H7 subtype is reportable in many areas of the world (including Canada), due to the potential for massive mortality in domestic bird flocks, as well as the risk of severe illness in people should such a virus start to circulate in the human population.   Since 2004, avian influenza has been detected in Canada four times - highly pathogenic H7 types were found in British Columbia (2004) and Saskatchewan (2007), and low pathogenic H5N2 viruses were found twice, also in British Columbia (2005, 2009).  The latest outbreak in January 2009 resulted in the destruction of 60 000 birds on the BC premises where the virus was originally detected, as well as all the birds on a second premises where the virus was found just over two weeks later.  This disease is taken very seriously, and the response to these outbreaks by the Canadian Food Inspection Agency (CFIA) must always be swift and definitive.

The risk of highly pathogenic avian influenza to the general public in countries such as Canada that are (usually, though not at the moment) considered free of the disease is very low.  The virus cannot survive in poultry products (i.e. meat, eggs) that are properly cooked.  Contact with wild birds (dead or alive), particularly migratory birds that could potentially be from other continents, is likely the highest risk.  Pet birds are also susceptible to these viruses, so its important to prevent them from coming in conatct with wild birds as well, especially because owners have such close contact with their feathered friends.

More information on influenza in animals and people is available in our archives.

• Wood's lamp:  A Wood's lamp is simply a special ultraviolet light.  Approximately half of all Microsporum canis strains (the most common species of dermatophyte that causes ringworm in cats and dogs) will fluoresce blue-green under such a light. This type of testing is obviously very easy to perform.  However, other debris in an animal’s hair coat may fluoresce as well, and other species of fungus that cause ringworm do not fluoresce, so this test is not useful by itself in most cases.
• Microscopy: Sometimes ringworm fungus can be seen on hair shafts from an infected pet when examined under a microscope.  However, it is easy to confuse other debris and structures for dermatophytes.  Also, not every hair on an infected animal will carry the fungus, so it's possible to miss the infected hairs altogether with this test.
• Fungal culture: The best way to diagnose ringworm is to culture the fungus from the infected individual (person or animal). In animals, one of the best ways to collect a sample for culture is to comb over all the fur and skin with a new toothbrush, and then try to grow dermatophytes from the toothbrush. This allows the fur from all over the animal to tested, rather than just one little clump of fur plucked from one area.  It can also make it easier to get a sample from the face and paws of cats, which is where these animals often carry the fungus.  Although fungal culture is the best way to diagnose ringworm, remember that fungal culture takes much longer than bacterial culture – instead of days, it may take up to three weeks to grow some dermatophytes.

It's also important to remember that dogs, and more often cats, may carry dermatophytes on their fur even when they look healthy.  A positive fungal culture from an animal with skin disease, particularly a cat, does not necessarily rule out other diagnoses, so your veterinarian may still recommend other tests as well.  However, any animal with ringworm should be treated to prevent spreading the infection to other animals and people.

More information about ringworm is now available on the Worms&Germs Resources page, and in our archives.
 

New animal health products are released on a daily basis. A great deal of time, effort and money is usually spent to market these products - sometimes more than was put into developing them. As a consumer, it's important to think before you buy, especially with new products.  Take a moment to consider whether a product is right for your animal, and whether the product's intended use and claims are  reasonable. The biggest problems tend to occur with "alternative" or non-traditional products, which encompass a huge range of products that are aggressively marketed, with little to no research or testing to back them up.  Here are some specific points to think about:

• Ask for research proving that the product works. "Data on file", anecdotes and other non-scientific sources are not adequate. Demand published research in peer-reviewed scientific journals. That means that the research has been independently scrutinized. Published data are not a guarantee that something will work, because some journals are not very strong and may publish weak research, but the lack published research altogether may indicate that research was not done, was not done right, or showed no benefit to using the product. Regardless of the type of product, there is no reason why proper research cannot be done to prove it is beneficial if it actually works.
• When looking at promotional literature, read it with a bit of skepticism. Think about whether or not what they say makes sense. A good general rule that I have is something that claims to cure all that ails you, probably cures nothing.
• If promotional materials do talk about research, check if they did a proper statistical analysis to really show that the product is better than the alternative. Showing a difference in numbers between two groups really mean nothing without proper analysis. For example, you could flip a coin 10 times and get 6 heads and 4 tails. Someone else may flip the coin 10 times and get 5 head and 5 tails. Clearly there's a difference in the numbers, but does it mean there's a difference in the ability of the two people to toss a head or a tail? Absolutely not.
• Don't get taken in by endorsements from "big names". More often than not, they're being paid for the promotion.
• Consult your veterinarian about new products. Be aware, however, that bad science is often marketed to vets as well and your veterinarian needs to be equally diligent.

At the end of the day, it's still "buyer beware". However, thinking about these basic points may help weed-out some particularly poor products. Additionally, and more importantly, increasing demands by consumers to see solid supportive research may be the only way to get companies to actually invest in testing and research to make sure their products work.

For today's example, take African trypanosomiasis, also known as sleeping sickness.  This disease is caused by a protozoal parasite called Trypanosoma brucei, which is transmitted by the bite of tsetse flies.  The disease only occurs on the African continent, but it is endemic in 36 countries and poses a risk to approximately 50 million people.  There are actually two subspecies of T. brucei that cause disease in man.  Trypanosoma brucei gambiense tends to cause more chronic disease and has caused massive epidemics of sleeping sickness in the past.  Trypanosoma brucei rhodesiense causes more acute disease, tends to occur sporadically and is more common in tourists and travellers in Eastern and Southern Africa.  What a lot of people don't realize is that T. brucei rhodesiense is actually a zoonosis - the main reservoir of the organism is livestock, whereas the main reservoir of the gambiense subspecies is infected people.

The World Health Organization (WHO) places human African trypanosomiasis (HAT) on its list of seven neglected endemic zoonoses.  Some of the other disease on this list have also been discussed on the Worms&Germs blog, including rabies (one of our favorites), brucellosis and echinococcosis.  In the early 1960s, efforts to control HAT brought the prevalence of the disease down to less than 1 case/10 000 people.  Unfortunately, for a lot of reasons, the control efforts could not be sustained, and the African continent is now facing its third major epidemic of sleeping sickness.  Better and ongoing surveillance, treatment of infected animal reservoirs, and control of the vector tsetse flies are all important components of the WHO's control strategy for HAT on the African continent.

Dogs can be infected by both T. brucei gambiense and T. brucei rhodesiense, but they are not considered significant reservoirs of disease.  Dogs may be more important as sentinels for human disease in endemic areas.  There are, however, other Trypanosoma species that occur in dogs and people in North and South America, including T. cruzi, which causes American trypanosomiasis or Chagas' disease.

More information about zoonotic sleeping sickness is available on the WHO website, and more information about Chagas' disease in people is available on the CDC website.  Keep watching the Worms&Germs blog for more posts about trypanosomiasis in pets.

This report reiterates the infectious disease risks than can be associated with illegally imported animals, as well as some of the welfare issues (a second article reported that some of the birds in the illegal shipment were found dead when they reached the border).  It's also important to be aware of zoonotic pathogens that can be carried by even healthy pet birds.

Psittacosis, also known as ornithosis or "parrot fever," is caused by the bacterium Chlamydophila psittaci, which is commonly carried by psittacine (pronounced "sit-a-seen") birds, often without making them sick.  These birds may shed large numbers of C. psittaci in their feces.  When the feces dry they become dusty, which can result in people inhaling the bacteria as they work around the birds.  This is the most common way for people to become infected, and can result in pneumonia.  The infection can be treated with antibiotics if it is caught in reasonable time, but it can be very serious in some cases.  The bacterium can make birds sick as well in come cases, in which case the disease is called avian chlamydiosis.

More information on psittacosis is available in the National Association of State Public Health Veterinarians' Psittacosis Compendium and in the Worms & Germs archives.

Dogs may actually be able to get mumps too, but it's very uncommon.  Dogs living with recently affected children have been reported to develop similar signs of illness to humans, including fever, not wanting to eat and swollen parotid salivary glands, and antibodies to mumps virus have been found in some dogs.  It's also been shown that the virus grows well in canine cell cultures in the laboratory.  However, there are no experimental trials that have definitively demonstrated transmission of mumps to dogs.

Because mumps is caused by a virus, antibiotics are not useful for treating the infection.  In dogs suspected of being infected, specific treatment is usually not needed - just some TLC and most dogs recover within 5-10 days.  There are no reports of people getting mumps from a dog - this is primarily a disease of humans.

People, but not dogs, can be vaccinated for mumps.  The vaccine is part of the MMR (measeles, mumps and rubella) vaccine, which many people receive when they are children.  For more information about this disease and vaccination, see the website of the Ontario Ministry of Health and Long-Term Care.

Bartonella henselae

Between 5% and 40% of cats in the USA have B. henselae in their bloodstream. It is most common in cats from temperate areas, and is much less common in Canada. Bartonella spp. live in the red blood cells of their host – quite a clever strategy really, because it makes the bacteria readily available to be picked up by vectors like blood-sucking fleas, it protects the bacteria from the hosts immune system so it can live there for a long time, and it may even partially protect the bacteria from antibiotics. Cats can maintain a waxing and waning infection for months or even years. The bacterium is transmitted between animals by the cat flea (Ctenocephalides felis felis). Studies have shown that transmission does not occur between cats kept in a flea-free environment. Some ticks may also be able to transmit the disease. Diagnosis in cats is difficult – blood culture is the most reliable means, but it is not always sensitive. Antibody production only confirms exposure but not active infection. Polymerase chain reaction is often faster but no more sensitive than blood culture. An effective treatment regimen to eliminate B. henselae infection in cats has yet to be determined.

Transmission of B. henselae from cats to humans is thought to occur through contamination of scratches and bites (broken skin) with flea dirt (i.e. partially digested blood from the infected animal that is excreted by fleas = flea poop). Infection in individuals with weakened immune systems can be extremely serious or even fatal. In otherwise healthy people, the infection tends to remain localized, but can still cause massive swelling and abscessation of local lymph nodes. The type of disease that occurs may depend on the strain of Bartonella involved.

There are a few simple steps people can take to decrease the risk of cat scratch disease. These are particularly important for individuals with compromised immune systems, in which infection can be much more severe:

• Keep your pets flea- and tick-free. Effective treatment and prevention products are available from your veterinarian.
• Avoid or prevent situations that may result in bites and scratches from your pet. There is more information about this on the Worms & Germs Resources page and in our archives. If you do accidentally get scratched or bitten, be sure to clean the wound thoroughly. Consider seeking medical attention for bites in particular.
• Be aware of where cats come from. Stray or shelter cats less than one year old are most likely to be infected with B. henselae.

It is also important to note that there is NO evidence that declawing cats decreases the risk of transmission of B. henselae to humans!

As a point of interest, Bartonella quintana (a human-adapted Bartonella species) was the cause of trench fever in World War I, and was transmitted by lice.
 

The original article (translated from Russian) states that the people at risk are those in contact with cattle and other domestic animals. Echinococcus actually causes the same type of disease in cattle and livestock as it does in people – it forms slow-growing cysts in the lungs, liver or other tissues. When the cysts are small they usually don’t cause a problem, but eventually (sometimes even years later) they can grow to a size that interferes with normal organ and body functions. However, people do NOT become infected by contact with cattle, sheep or other intermediate hosts. The infection can only be spread to humans (and livestock) by the definitive host - dogs, including domestic dogs and wild canids. In dogs, the parasite lives in the intestine in the form of a tiny adult tapeworm, and the tapeworm eggs are shed in the dog’s stool. When the eggs are swallowed by an intermediate host, the immature form of the parasite penetrates the intestinal wall and migrates through the body tissues to the site where it ultimately forms a hydatid cyst. If the animal dies or is killed, and the cyst is eaten by a dog, then the cycle begins again.

The most probably reason for the increased number of human infections in this case is an increase in the number of dogs in the same area, particularly those used for herding sheep. This may be equivalent to the dog-reindeer cycle present in Siberia.  Echinococcus infection in dogs can be treated with common deworming agents that kill other tapeworms, but it is likely that dogs in these areas are not dewormed as often as they should be to prevent this disease.

The article reiterates some sound recommendations for decreasing the risk of Echinococcus infection. These may sound familiar, because many of them also help decrease the risk of transmission of infectious diseases in general:

• Wash your hands after contact with animals.
• Wash your hands after working in orchards where cattle have wandered (not the most widely applicable recommendation for people living in North America, but is along the same lines as our recommendation to wash your hands after working outside, particularly with soil).
• Do not consume unwashed greens or vegetables (all fruits and vegetables should be thoroughly washed with potable water before being processed or eaten).
• Do not drink water from untreated sources.

More information about Echinococcus and other tapeworms is available in the Worms & Germs Archives.

Photo: Central Asian Shepherd Dog (Sredneaziatskaya Ovcharka), click here for source (Wikipedia).