Worms & Germs Blog

A near fatal dog lick?

Posted in Uncategorized

I like to write about interesting papers that appear in the medical literature. A problem with that is that it’s often weird cases that get published.

So, it’s important to keep things in perspective.


Regardless, reports of rare things still provide some insight, as long as people don’t over-react (which, unfortunately, is often the case).


Great example…a case report entitled “An unusual case of meningitis” in the Canadian Journal of Infectious Diseases and Medical Microbiology (Pond et al, 2015).


The short version…

  • A 56 yr old man with chronic ear discharge and a perforated eardrum was admitted to hospital for ear surgery.
  • Post-operatively, he developed neurological disease and was diagnosed with meningitis. Ultimately, it was identified as being caused by the bacterium Pasteurella multocida. This bacterium is most commonly associated with the mouth of cats and dogs (particularly cats) and periodically causes infections in people.
  • Finding this bacterium led to investigation of pet contact (ideally, this is queried routinely, not just in response to a potential pet-associated infection) and it was discovered that the man took care of several cats and a dog.
  • There was no history of a bite (a common source of Pasteurella infection) but the pets were occasionally allowed to lick his face. That’s presumably the route of infection here, although there was no further investigation.
  • The good news, he recovered.


I get asked about risks associated with licking all the time. My typical response is that I don’t like my dog licking me, but it’s not a germaphobic thing, I just don’t particularly like it. The risk to most people is quite low. I do recommend that licking of people at increased risk of infection be avoided. That would include infants, elderly individuals, people with compromised immune systems or people with open sores be prevented. I especially recommend avoiding licking around the face, for a few reasons.

The person in this case report would have fallen under the higher risk group, by virtue of his chronic ear problems and perforated eardrum. Licking around the ear would pose an increased risk of the bacterium accessing the brain through the ear and perforated eardrum. Certainly, it’s a rare problem, but it emphasizes the need for people at increased risk of infection to take additional precautions.

A big problem there is identifying those individuals and getting them information about what to do or not do. Better communication between vets and physicians, routine questioning of pet contact and better access to basic information materials (like the info sheets we have in our Resources section) are important aspects of this.

Cats, Toxoplasma and mental health (with a side of over-exuberant reporting)

Posted in Cats, Toxoplasmosis

Cat paw over faceThere’s been a lot of discussion about toxoplasmosis and mental health over the past few weeks in response to a paper in Schizophrenia Research (Torrey et al 2015). Some internet sources are having a great time writing “crazy cat lady” and similar headlines.

But is there any substance to it?

Yes, and no.

The science in the paper that’s being cited is pretty limited. From my reading of it (and I doubt most people that have written about the paper actually read it), the paper wasn’t meant to be a definitive answer. It was meant to raise awareness.

It certainly did that.

The content relates to the protozoal parasite Toxoplasma gondii. Cats are the definitive host, meaning the adult stage of the parasite lives in the intestinal tract of cats. If infected, cats can pass eggs in their feces. After a few days outside the cat’s body, these eggs are able to infect people, if ingested. A reasonable percentage of healthy people have been exposed to Toxoplasma, potentially directly from cat poop, but more likely from general environmental exposures (e.g. gardens, sandboxes) or unwashed vegetables. Rarely does disease occur, and the main concerns are for severely immunocompromised individuals (who can get Toxoplasma encephalitis (i.e. inflammation of the brain)) and for pregnant women who have not been exposed to the parasite previously (in which the parasite can cause severe infection or death of the fetus).

There have been lingering concerns about the role of toxo in other diseases, schizophrenia being one of them. There have been two studies that suggested a link, but the evidence was relatively weak:  basically they simply found that the incidence of cat ownership while young seemed to be more common in schizophrenia patients compared to a control group.

The Torrey study set out to look at that again, using existing data. They looked at data from a 1982 survey of families of schizophrenic patients, collected from people that attended the National Alliance for the Mentally Ill (NAMI) convention. They compared those numbers to a 1991 survey of the general public reported by the American Veterinary Medical Association. Cat ownership was 51% in the schizophrenia population and 43% in the AVMA survey. So, it’s suggestive.

However, these are two completely different studies of different groups in different decades using different methods. A control group has to be very well matched to a “case” group to make a valid comparison, something that may not be true here (there’s no way to know).  Various confounding factors could be present. For example, the paper mentions that at the time of the 1982 survey, people with schizophrenia tended to be disproportionately middle and upper class. That would probably be biased even further by including only people that attended a convention (and had the money, time and motivation to go). Could that type of person also be more likely to own a cat?  Could that have affected the results? Certainly, it must be possible.

A key point that’s being missed by most reports is the final paragraph of the paper.

It is important to ascertain whether or not cat ownership in child-hood is a risk factor for later schizophrenia since it is a risk factor which could be minimized. We therefore urge our colleagues in other countries to collect data on cat and other pet ownership, and a major goal of this paper is to encourage such research.

It’s important to ascertain….

More work needs to be done….

Not, ‘”cats cause mental illness.”

It’s good to pay attention to the potential link and properly explore it. At the same time, toxo avoidance measures are very easy for cat owners. They include:

  • Cleaning the litterbox daily
  • Avoiding contact with cat feces, especially old feces
  • Handwashing after contact with the litterbox or feces
  • Keeping your cat inside so it doesn’t get infected by eating infected rodents
  • Keeping sandboxes covered to they don’t become neighbourhood cat litterboxes.

More information about toxoplasmosis can be found in on the Worms & Germs Resources – Pets page.

Giardia in dogs

Posted in Dogs

Beagle PupThe parasite Giardia often raises concern for both dog and human health. In reality, while it’s a potential problem, it’s probably over-rated (or at least there’s a bit too much paranoia at times). A reasonabe percentage of healthy dogs (probably ~7% in Ontario) are shedding the parasite at any given time, but very few will go on to develop disease. It can cause diarrhea, but only in a small minority of exposed animals, and usually it’s not a big deal. Giardia also a zoonotic pathogen, but as we’ve learned more about this parasite in recent years, it’s becoming clear that pets pose a limited risk to people. Most studies have identified Giardia found in dogs to be dog-specific strains that do not infect people.

Here are some interesting tidbits about Giardia from a few recent papers.

Does that mean we should just ignore Giardia? No. It can definitely cause disease in dogs, and sometimes it’s hard to treat. It can also cause disease in people (I spent a couple days in hospital with Giardia many years ago… never did figure out how I got it). It’s important to remain balanced, though. Pets are a minimal to inconsequential source and people shouldn’t freak out if their dog is diagnosed with Giardia. At the same time, it’s a “don’t eat poop” disease, so basic prevention practices are easy.

More dog travel issues

Posted in Dogs, Rabies, Vaccination

Importation issues, Part 1

FB Post - AzerbaijanA Facebook post was forwarded to me the other day. It reads “Drove to the airport today to pick up this lovely little girl [puppy] who flew all the way to Montreal from Baku Azerbaijan. Spent the afternoon with her romping around in Westmount Park. She will be up for adoption at ____ Animal Society and is seriously cute.”

There are a few issues here. Among them is taking a stressed (probably exhausted) puppy to a busy park after a very long trip. The infectious disease concern is taking this puppy (hard to say what it’s vaccine or deworming status is) from the other side of the world and immediately exposing it to other animals. That poses risks to this pup and others at the park. It’s also likely an illegal importation. Dogs that are not being brought in by their owners are considered commercial imports. Regulations specifically state that dogs coming in as rescues are considered commercial. Commercial importation of dogs <8 months of age that do not come from a registered kennel is illegal. Otherwise, they must have a rabies certificate, veterinary certificate of health, microchip or tattoo and an import permit. I doubt this dog had those.

Canine flu

Canine H3N2 influenza continues to spread across the US (likely after it came into the country with a dog imported from Asia). Click here for a map of CIV in the US and testing summary from Cornell University Animal Health Diagnostic Center.  The spread of the virus has been facilitated by inter-US travel; people taking their dogs on vacation to areas where the virus is active and bringing it home with them. I’m not saying dogs shouldn’t move within a county. It would just be wise for people traveling with their pets to do a little research into issues in areas they will be visiting. That might indicate a need for vaccination or anti-parasitic treatment for something not native to their home region, or identify a concern like H3N2 flu. If at all possible, people should not travel with their dogs to areas where H3N2 is active. If they do, they should make sure their dogs stay away from local dogs and, when they return home, that their dogs stay away from other dogs for a week or two in case they were infected.

Rabies in France (Importation issues, Part deux)

A few days ago, 13 adults and 3 kids in France started rabies post-exposure treatment after contact with a rabid puppy. As is the common story with rabies cases in that region, the dog was imported illegally. The dog came from Hungary in December, then accompanied its owners to Algeria in April. It began to show signs of rabies May 16, and the virus strain that was isolated was the Africa 1 strain, consistent with infection acquired in Algeria.

There were a couple breaches of the law in this case. Its initial importation from Hungary was illegal because it was not of the minimum age for importation, had not been vaccinated and had no identification. (Sadly, those wouldn’t be illegal in Canada. For importation of a personal pet, we don’t have a minimum age, and puppies less than 3 months of age don’t need to be vaccinated against rabies. There’s also no tracking. Dumb but true.) Its return from Algeria was also illegal. So, these owners who flaunted the law twice (and presumably didn’t ever get the dog vaccinated against rabies), combined with absent regulatory scrutiny led to the death of this dog and (expensive) treatment of at least 16 people.

Equine infectious disease research: Call for Ontario participants

Posted in Horses, Miscellaneous

Are you an Ontario horse owner? University of Guelph researchers now recruiting for new equine project!

Horses travel frequently, and the nature and extent of these travel patterns can contribute to the introduction and spread of diseases. The University of Guelph is conducting a study to determine how these movement patterns can influence new disease prevention strategies. We are currently recruiting participants to complete short monthly surveys (requiring less than 10 minutes of your time) about where and how frequently you travel with your horse. By joining our study, you would be contributing to the first study in Ontario to determine how disease prevention can be linked to movement patterns of horses. There is also a draw for prizes for participants!

To join the study or learn more, please visit: http://www.mathepilab.org/equinestudy2015/ Advertisement2COLOUR copy 2

Horses, strangles, streptococcus

Posted in Horses

Horse whiskers-1A paper in the journal BMC Research Notes describes a case of meningitis in a 73-year-old man that was attributed to contact with a horse (Madzar et al 2015). The man was admitted to hospital with fever, headache, neck stiffness, malaise and drowsiness. He was ultimately diagnosed with meningitis caused by Streptococcus zooepidemicus (technically, Streptococcus equi subsp zooepidemicus). He recovered, but ended up with significant loss of vision in one eye.

As is frustratingly common, there was no apparent investigation of the source of infection. It’s good that physicians asked about animal contact, but it would be nice to see some more effort to confirm the source (e.g. try to isolate the same bug from the horse and show it was the same strain). The report says the man was working with a horse with strangles, which is a little strange since that disease is caused by S. equi subsp equi, not S. zooepidemicus. Some potential explanations include:

  • The hospital lab misidentified S. equi as S. zooepidemicus.
  • The horse had a S. zooepidemicus that looked like strangles and the diagnosis wasn’t confirmed.
  • The two infections were unrelated.

Strep zoo infections are rare in people, despite the bacterium being very common in horses, and also found occasionally in some other species like dogs. The rarity of the problem is highlighted by the fact that a single case report made it into the literature. If it wasn’t an oddball case, it wouldn’t have been written up.

I often hesitate to write about rare things like this. It can cause an overreaction if people don’t put it into context. This is one of many bacteria that can cause infection given the right circumstances, but  those “right circumstances” are rare. Every animal and person is carrying many microbes that could cause disease in another person or animal, but it usually doesn’t happen. For me, cases like this highlight the importance of good routine infection control and hygiene practices, as well as the need for physicians to collect animal contact information from patients.


US Turtle Laws

Posted in Reptiles

Turtle close upTurtles are notorious Salmonella vectors. Because of that, various jurisdictions have rules limiting their sale, particularly the sale of small turtles (i.e. those that young kids are more likely to handle and try to put in their mouths). A recent publication from the CDC’s Office for State, Tribal, Local and Territorial Support is a Menu of State Turtle-Associated Salmonellosis Laws. It gives a good rundown of the different approaches used in different areas of the US.

Some are fairly strict, some more lax, and some are non-existent.

It’s interesting that some places ask for certification that turtles are Salmonella free. I’m not aware of any way to truly be confident in confirming that, and it’s a pretty weak approach. Striving for Salmonella-free makes sense. Killing Salmonella positive turtles isn’t logical, and selling “Salmonella free” turtles can lead to a false sense of safety.

Speaking of information, the Worms & Germs turtle infosheet can be found on the Worms & Germs Resources – Pets page.

The key aspects that help to control turtle-associated salmonellosis are fairly common on the menu, including keeping these high-risk animals away from high-risk people. Some states have requirements for warnings to be posted and for purchasers to review information. Those are the types of basic, easy and cheap measures that (if followed…now that’s another story) can likely have a very beneficial impact.

Small flocks, urban chickens and bird flu

Posted in Birds

Three poultry flocks in Ontario have been found to be infected with H5N2 highly pathogenic avian influenza (HPAI).  Under the direction of the Canadian Food Inspection Agency (CFIA), the lead agency when it comes to responding to federally reportable diseases like this, disease control zones have been established around the affected flocks, and movement of domestic birds and poultry products in and out of these zones is being carefully controlled in order to try to prevent further spread. Waterfowl flyways mapNo one knows for sure how the virus made it into these flocks.  Based on the fact that an almost identical flu virus was found in British Columbia and along the west coast late last year, and that the virus has recently been popping up with disturbing frequency in the central US, it is suspected that the virus is moving around in wild birds.  Migratory waterfowl in particular are prime candidates, as they travel long distances along certain routes such as the Mississipi flyway (which includes southwestern Ontario), and they generally don’t get sick from the virus, even though it’s highly fatal in domestic poultry. Commercial poultry flocks tend to have a lot of biosecurity and infection control procedures to prevent wild birds (or feces of wild birds) from coming in contact with the domestic birds, but sometimes some of the virus slips by one way or another, and it doesn’t take much to infect the flock when the virus is so pathogenic.  But the domestic birds that are most likely to have exposure to wild birds are small backyard flocks and birds like “urban chickens”.  There are also some wild bird species like raptors and wild turkeys that are susceptible to the virus (and it just so happens that turkey hunting season starts on Monday here in Ontario). It’s important to note that the risk to people posed by this particular virus is very low.  No human cases of H5N2 have been reported, despite the numerous outbreaks in poultry flocks across the continent. It is also not considered a food safety risk, but of course raw poultry and poultry products still need to be handled and cooked properly for lots of other reasons (like Salmonella).  There is some potential risk to those who have a lot of direct contact with infected birds though, so its important for backyard chicken enthusiasts and people like hunters to be aware of the potential risk.  These groups can also help with surveillance and monitoring by helping to identify affected birds in different areas so they can be tested for HPAI, thus helping to track the movement of the virus. The Ontario Animal Health Network (OAHN) has put together an infographic to help small flock owners and bird enthusiasts remember what to do to help detect and stop the spread of bird flu. OAHN has also put together a podcast and resources for both veterinarians and producers. Click here for the small flock advisory from the Ontario Ministry of Agriculture, Food and Rural Affairs. Avian Influenza Infographic -FINAL(1)    

Do headline writers actually read the articles?

Posted in Dogs

Newspaper2Part I Lyme disease is accompanied by enough paranoia. Bad headlines don’t help. A recent article on The Daily Mail is about Lyme disease and pets. It’s actually not a bad article, outlining some important issues. However, the headline shows a big disconnect between some good content in the article and a complete misunderstanding of the situation. The title: Warning to dog owners over the ticks that can wreck lives: Many are unaware their pets can transmit potentially deadly Lyme disease to them, say vets  To be brief, pets can’t transmit Lyme disease. Ticks that infect pets can also infect people, but that’s it. Part II Dr. Jason Stull (newly minted Canadian) spearheaded a commentary in the Canadian Medical Association Journal with Dr. Jason Brophy (infectious diseases physician) and myself. The article raises the issues of zoonotic diseases and pets, particularly in high risk people, and the need for physicians to have increased awareness thereof. It outlines some of the important issues, how pets and pet contact are common, what things increase the risk, the need for more information about pet-associated disease, and the need for people to take reasonable precautions to reduce the risks.

The title of the paper is important to consider: “Reducing the risk of pet-associated zoonotic infections

The paper’s attracted a lot of attention. Some good. Some not. Many reporters have spun it towards sensationalizing the risks. Here are some examples of (bad) headlines:

  • Experts warn pets can cause illnesses, especially in immunocompromised owners
  • Your furry friend may be carrying diseases
  • Pets can make their owners sick, researchers say
  • Who let the dogs out? Pet therapy’s hidden danger

…and my favourite:

  • 8 disgusting diseases you can catch from your pet

I guess those headlines are catchy, but the key point is not that your cat or dog is likely to kill you. The key points are:

  • Physicians need to query pet contact when individuals become ill.
  • People need to think about basic routine practices to reduce the risk of disease transmission from pets, especially in high risk households.
  • We need more information about pet-associated diseases.

More accurate, but perhaps less catchy, headlines might have included:

  • Wash your hands, don’t eat poop and don’t be stupid, researchers say
  • Docs need to ask if patients have contact with animals

Probiotics…above all, do no harm?

Posted in Horses

Foal recumbentProbiotics are popular treatments for any number of ailments (in animals and people), but marketing, especially on the veterinary side, massively outstrips research. A few years ago, I worked on probiotic development in horses. We found what looked like a good candidate bug, but instead of just trying to sell it, we did a proper trial. Despite the positive properties it showed in the lab, it actually caused diarrhea in foals compared to a placebo group. Oops. (Does that make me a bioterrorist or just a really bad probiotic developer?) Anyway, history repeated itself with another probiotic trial in foals that was just published (Schoster et al, J Vet Internal Med 2015). Despite some promising results in the lab, foals treated with this bacterial combination were more likely to develop diarrhea that required veterinary care compared to untreated foals. I don’t mean to say that all probiotics are bad. However, the “well, you have nothing to lose” approach that is often taken with probiotics (and other nutraceuticals) may not be appropriate. Probiotics, and other nutraceuticals, should be properly scrutinized like any other kind of treatment or therapy.