Worms & Germs Blog

Close Encounters of the ‘Tick’ Kind…Your Pet, Pathogens & Lyme Disease

Posted in Dogs, Horses, Other diseases, Parasites

Guest Blog by Dr. Michelle Evason DVM DipACVIM, and current PhD student researching Lyme disease in dogs

Recently, an interesting article on pet ownership and human tick risk was published (Jones et al, Zoonoses and Public Health 2017). The study looked at risk factors for “tick encounters” in people living in Lyme disease endemic states in the US.

Somewhat unsurprisingly (for anyone who likes to pet & play with their pets or allows them outside), the study found that people who owned pets had 2x the risk of finding ticks crawling on them (and 1.5x the risk of tick attachment) compared to households that didn’t have pets. While I’m really hoping that anyone reading this doesn’t decide that getting rid of their dog, cat, horse or other is my recommendation to solve this concern… I am REALLY hoping that people DO consider protecting their pets from tick attachment through the use of veterinary approved prevention methods (if they aren’t already), regular tick checks of their animals (especially prior to letting them sleep on the bed), and also strongly hoping that people consider protecting themselves (and their children) with tick prevention methods when they are outside (with or without their pets) in areas that are higher risk (e.g. forest, long grass) or if they live in declared Lyme endemic regions of Canada.

Ticks are a hot topic in parts of Canada, as they’re spreading pretty steadily across some parts of the country. There are lots of ways to prevent Lyme disease (or a number of other tick-borne diseases), and still enjoy the beauty and bounty of the Canadian summer and fall… and they all begin with awareness of why and how disease occurs. Right now, in Canada one of the increasing causes of clinical infectious disease illness in people and their dogs (and horses) are TICKS! This link from the CDC is a great guide to ways to provide protection from ticks in humans, and your veterinarian is an excellent guide to information on prevention for any 4 legged friends you may choose to co-habitate with.

As plenty of you know, there is a current lack of consensus regarding many of the clinical questions (diagnosis, treatment, prognosis) the veterinary community has about dogs (and horses) infected with Borrelia burgdorferi, the agent of Lyme disease.

These clinical questions about Lyme disease exist across species (i.e. canine, equine and human) and while I am frequently confused about what the term “One Health” actually means, if I get to choose a definition this would be it: Various animals (yes –  humans are animals) infected with the same bug and getting a similar disease from it. So, it’d be great if we could all just team up and pool our knowledge on the topic. To be fair, Lyme is an extremely difficult disease to research outside of the lab; clinical Lyme disease is very hard to reproduce experimentally and we think only a very small percentage of dogs exposed to Borrelia burgdorferi via Ixodes tick bites develop disease. Furthermore, it’s not as if zero research on this particular pathogen is occurring, and if it was an easy disease to study we’d already have the answers to these questions… and it’s pretty clear by now that we just don’t.

Wouldn’t it be great if someone (or a group of someone’s) came along and decided to develop a study that followed young dogs along and watched, looked and listened to their devoted owners and veterinarians about what happened if/when they were bitten by a tick carrying the agent of Lyme disease, so we could move past (or try to) this lack of consensus and information and find some answers for all of us? Unfortunately, studies like this are hard to do, mainly because it’s tough to get people to take the time to enroll, answer questions and then do so repeatedly. It’s also tough to get funding for research that takes this kind of time, and as such longitudinal/lifetime studies are challenging to perform and to some degree are a total academic gamble. On the other hand, research studies like this have been attempted and done quite successfully in humans, such as the groundbreaking Framingham heart study and more recent Guelph Family Health Study.

Both of these have helped (and likely will continue to help) answer a great number of clinical questions that have paved the way to clearer understanding of disease, and perhaps even more importantly prevention. That’s why we’ve recently launched the Canadian K9 Lifetime Lyme Study and are part of a similar initiative in the USA, to try to answer some of these questions. More to come on those…

Rabid Horse: Minnesota

Posted in Horses, Rabies, Vaccination

If a horse comes into the hospital at this time of year and has some difficulty standing, incoordination and mild fever, the first thing on my list of likely causes is probably equine herpesvirus type I (EHV-1) infection. Next would be West Nile virus encephalitis. However, we consider all sudden onset neurological disease cases in Ontario to be rabies suspects, just in case.

Rarely is it actually rabies, which can lead to less attention to the potential for rabies infection and sometimes an approach of “we’re calling it a rabies suspect because we have to, but we really don’t think it’s a big deal.” That can lead to less care with infection control practices. However, even though it’s rare, it still happens. A recent case of rabies in a horse in Minnesota should be a reminder of that.

The scenario was similar to that described above: the horse had a hard time standing, was incoordinated, had facial spasms and a low grade fever (facial spasms would get me thinking more about West Nile since that was a pretty common sign when we saw the first wave of equine West Nile cases here in Ontario in the early 2000s). The horse was euthanized after failing to respond to treatment, was tested and was positive for rabies. Post-exposure prophylaxis (PEP) was recommended for the owner, three family members, the vet and a vet student.

As is common, a clear source of infection wasn’t identified. A skunk source is suspected because skunks are a rabies reservoir in that region, and the owner reported smelling a skunk in the area a couple months earlier (consistent with the rabies virus incubation period).

There’s no mention of whether the horse was vaccinated against rabies. I’d guess that it wasn’t, since rabies vaccine is pretty effective. While rabies is rare, this is a good reminder of the need for vaccination against this almost invariably fatal zoonotic infection, and the need to approach neurological horses with care.

Fatal viral infection from a cat?

Posted in Cats

One thing that’s a given with infectious diseases is that there’s always something new to learn. Interestingly, I had a couple enquiries about an obscure virus last week, and was subsequently sent a link to a news report about the same disease: severe fever with thrombocytopenia virus.

As the mouthful of a name suggests, the virus causes a syndrome characterized by severe fever with thrombocytopenia (low platelet count). It’s a tick-borne virus that was initially found in China.  The reported mortality (death) rates range from 6-30%, which would make it one of the more serious infectious diseases one can get. However, like many “rare” diseases, it’s possible that it’s actually more common and less severe overall than we realize. If only people who are very sick get tested, that biases the death rate to a higher level. It’s possible (although completely speculative on my behalf) that many other people get sick, get better and never get diagnosed (or possibly even get infected and never get sick at all). It’s a possibility we always have to consider when interpreting death rates from rare diseases.

The news report involves a woman from Japan who died last year from this disease. The unique aspect of this case is that she was caring for her sick cat, and was bitten by the cat. She didn’t have any known tick exposure so doctors hypothesized that the cat was the source. However, it’s not known whether the cat was infected or whether it can be spread by a cat bite. That leaves this very speculative but something to consider.

While it’s unclear whether the cat was the source of infection in this case, it’s a good general reminder of the need to use basic hygiene practices around animals (especially sick animals), to take care to reduce the risk of bites and to promptly and thoroughly clean bite wounds. That doesn’t prevent all infections, but it can reduce the risk.

Clostridium difficile, hospital visitation and dog risk

Posted in Dogs

A reader has been trying to post a question about an older post on C. difficile in visitation dogs. Here’s the question and my answer:

Do the dogs have a risk of getting sick from the C. difficile bacteria?  I understand from the post that they can ingest and shed it in their feces, but the post never states whether they can get sick from the bacteria or not!

It’s a great question, and it lacks a similarly great answer. We don’t really understand C. difficile in dogs. We’ve made an association between the presence of C. difficile toxins in feces and the presence of diarrhea in dogs, but there are a few things that cloud our understanding of whether C. difficile is actually a significant problem. My guess is that C. difficile is a cause of diarrhea in dogs, but it’s not a major one. Or, maybe more accurately, it’s not a common cause of serious disease. It might be a relatively common cause of mild disease that gets better on its own (and therefore just doesn’t get diagnosed), but is an uncommon cause of serious disease. Dogs don’t get recurrent C. difficile infection or pseudomembranous colitis like people do, and those are the two most serious and recognizable forms of disease. Given the commonness of exposure (dogs probably ingest a small number of C. diff spores on a routine basis) and the low apparent incidence of disease (at least serious disease), it doesn’t seem to be a major health risk.

Echinococcus multilocularis: Alberta, Canada

Posted in Dogs, Parasites

Several news articles have been written lately about the recently-described cases of Echinococcus multilocularis infection in four people in Alberta. The cases of alveolar echinococcosis have occurred over the past 4 years, and raise significant concerns.

Echinococcus multilocularis is a small tapeworm but it causes big problems.


  1. It’s a potentially nasty parasitic disease that can act a lot like a tumour.
  2. By the time it’s recognized, treatment can be difficult.
  3. Since the incubation period is 5-15 years, infections identified now developed many years ago, and there are probably other people who are infected and don’t yet know it.
  4. This number of cases, combined with evidence of the parasite in wild canids (foxes, wolves, coyotes) in a couple of regions in southern Canada suggest the parasite is well established in certain parts of the country (besides the arctic) and probably beyond.

Eradication of this parasite isn’t practical in regions where it’s established, since it’s presumably well entrenched in the wildlife population. Its life cycle includes infection of small mammals (mainly rodents), that develop tumour-like lesions in their internal organs (typically liver). When the animal is eaten by a canid, the tapeworm develops in the intestinal tract, where it produces eggs. These eggs are shed in feces and the life cycle continues when another small critter ingests an egg. People can also develop the tumour-like lesions if they inadvertently ingest tapeworm eggs. Dogs can occasionally be infected in this manner too, but more often develop the intestinal infection after eating an infected rodent, and then shed eggs (which then poses a risk to people and other animals).

Here are a couple resources for more information:

Worms & Germs Blog Echinococcus Fact Sheet

Public Health Ontario’s 5 things to know about E. multilocularis

For veterinarians, the Ontario Animal Health Network (OAHN) infographic Emerging Risk: Echinococcus multilocularis in Ontario

Psittacosis in a Pet Store Worker

Posted in Birds

Following up on yesterday’s post about a bird-and-fish-associated infection, this next story also involves a pet bird, but with a much worse outcome. It involves a young woman who developed a very serious case of psittacosis linked to her job in a pet store. Psittacosis is a bacterial disease caused by Chlamydophila psittaci, a bacterium that is linked mainly to psittacine birds (i.e. birds in the parrot family), and it’s one that is easy to overlook if bird contact isn’t considered.

The woman sued the pet store where she worked and the associated companies, receiving a multi-million dollar settlement to help compensate for her for the devastating complications of infection, including brain damage. The lawsuit alleged that she contracted the infection from a cockatiel that the store purchased. It’s not clear how/if that was confirmed, but it’s a reasonable source.

Importantly, the focus of the claim isn’t that she was exposed to C. psittaci. Rather, it’s that she had received no health and safety training for her job. That’s an important distinction because there is an ever-present risk of zoonotic pathogen exposure when there’s contact with animals. Whether it’s a personal pet, petting zoo or job in a pet store (or vet clinic), exposure is always a risk. The key is the need for people to know the risk and what they can do to reduce the risk. If a workers (or pet owners) have this information, they can make an informed decision about whether or not they are willing to accept that risk. If they are not educated and trained, they can’t. The pet store can’t be the one deciding whether an employee is willing to accept the risk. The employee has to do that, after being given the tools to do so. Too often, education is lacking, whether it’s a pet store employee, petting zoo visitor or pet owner. That’s what more lawsuits are focusing on, and cases like this should highlight the importance of education and training.

Another component of this case that wasn’t discussed in the article is the medical care the plaintiff received . Psittacosis can be severe but is also treatable, especially if caught early. As has been a common theme on this blog, obtaining animal contact history is a key aspect of successful treatment of zoonotic diseases, but unfortunately one that’s rarely done right.

A Bird, Some Fish and a Near Amputation: Bizarre Headline but an Important Story

Posted in Birds

Why is it that zoonotic disease case reports in the scientific literature sometimes get titles that are…well, let’s just say “creative.”

A recent example of a strange headline for an interesting case report is “The Brief Case: A Fishy Tale Prevents Digital Doom following Polly’s Peck—the Importance of Pets in a Comprehensive Medical History” published in the Journal of Clinical Microbiology (Simpson et al. 2017).

I guess it’s a double zoonosis, as the infection described was linked to both a bird and fish. Birds are more commonly implicated in zoonotic infections but fish-tank associated infections occur, usually by the bug implicated in this report.

Here’s the short version of the story:

  • A 68-year-old man was bitten by his pet African Grey parrot. He’d be in a high risk category for infections based on his age, as well as his medical history. He went to a physician the day after the bite and was given oral antibiotics because of inflammation at the site of the bite. Swelling persisted and some further testing (a couple of months later) showed likely infection of the bone.
  • Over a year later, he went back to his doctor with worsening finger swelling, and the next month a rheumatologist injected one of the finger joints with steroids to reduce inflammation. The problem is, steroids reduce inflammation by suppressing the immune response, and when there’s an infection present, suppressing the body’s response often leads to badness. Consistent with that, things had worsened by the next month, more aggressive care was needed, and amputation was considered.
  • Eventually (a long time later), a diagnosis of Mycobacterium marinum infection was made. This bacterium is associated with fish and fish tanks, and infection is often referred to as “fish tank granuloma.” The parrot bite set the scene for infection by damaging the skin and allowing the bacterium to access the site. The person’s age and health status reduced the ability to eliminate the bacterium, and the steroid injection blew things wide open.
  • Fortunately, over many months of treatment, he responded and full function of the finger was regained.

An important part of this story is the statement that “A comprehensive medical history revealed that, in addition to the African gray parrot, the patient kept tropical fish and had cleaned the fish tank thoroughly following the parrot bite.”  This only came out over a year after the onset of disease, when an infectious disease team was involved. It’s a common theme on this blog, but while pet-associated infections are uncommon, getting pet contact history when infection does occur is critical and unfortunately rare. Here, as in countless other cases, failure to get that information was a key part of the pathway that lead to complicated and prolonged disease.

As is stated in the paper, “Pet ownership is an often neglected part of a medical history with both patients and health care professionals sometimes being unaware of the potential risks of zoonotic diseases. In this case, eliciting multiple pet ownership—after an 18-month diagnostic delay— contributed to saving this gentleman’s M. marinum-infected finger from amputation”.

Dog Bite Near-Death: A Cascade of Missed Opportunities

Posted in Dogs

warning-dogA few sentences into a Washington Post article entitled “A dog bite sent him to the ER. A cascade of missteps nearly killed him”, I was thinking, “This sounds like a pretty typical Capnocytophaga canimorsus infection. I wonder if this guy lost his spleen earlier in life.”

It turns out that was true. Unfortunately, neither the person with the infection nor the initial healthcare providers had the same thought. It almost cost him his life, and we need improvement on both sides.

The scenario is pretty typical for infections caused by this bacterium, which is found in the mouths of most (or all) dogs. Rarely does it cause disease.  People without spleens are actually the highest risk group, but they often don’t consider themselves immunocompromised.

The affected person in this case had been bitten by a neighbour’s dog 3 days before he got sick. The wound was washed out, and he went to an urgent care clinic the next day. He got a tetanus shot, and while the doctor offered antibiotics, he decided to forgo them.

The next day, his condition started to go downhill, and it progressed to the point where it wasn’t clear whether he would survive. Fortunately, he did pull through, ending up with profound hearing loss and amputation of a few toes. However, even though those are significant issues, he’s lucky. Most people die. Those who survive often lose multiple limbs or have other severe consequences.

This scenario shows a cascade of inadequate education and missed opportunities that ultimately could have cost him his life. At various points in the process, there were opportunities for intervention by both the patient’s family and the healthcare team.

1. Time of splenectomy

People who have their spleens removed need clear counseling that their immune system is compromised. As part of that, they need to know that if they are ever bitten by a dog, they must get antibiotics.

2. Time of dog bite

Good wound care, as was done here, is critical, but it’s also important for the person to see a doctor, to tell the doctor they don’t have a spleen, and to make sure they get antibiotics.

3. Doctor visit

Any evaluation of a person bitten by a dog should include a question about immunocompromise, and specifically if the person has lost their spleen. If the answer is yes, they must get antibiotics.

4. Hospital admission

The bite needs to mentioned initially (and repeatedly). It’s an abnormal event that preceded an abnormal medical situation. That doesn’t mean it’s always the cause, but it needs to be noted. Here, the bite wasn’t mentioned at the start.

Healthcare personnel also need to be notified that the person has no spleen. Since universal electronic medical records aren’t available, hospital personnel don’t have access to everyone’s full medical history on admission. This is a critical piece of the puzzle for a case like this.

We’ll never know, but if the patient in this case had been started on antibiotics at that first visit (or on the day of the bite, ideally), it’s likely that none of this cascade would have happened.

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

Things Not To Do With Raccoons

Posted in Parasites, Rabies

1) Pick up baby raccoons and take them away

  • Raccoon litter JVGRarely does this end well. It’s illegal in many areas (including Ontario). Raccoons don’t do well long-term in households for various reasons (their curious and destructive nature being a big one). And, they are potential sources of a number of zoonotic diseases (rabies being a big one but not the only concern).

2) Take them to a bar

  • This could be simplified to “take them anywhere.” The more people encounter the raccoon, the more people might be exposed to the pathogens it carries.

Seems like common sense, and yet people picking up cute raccoon kits and taking them somewhere (though not necessarily a bar) seems to happen all the time. A recent incident in Pendletown, NY, highlights the issues. A woman picked up a baby raccoon from a litter of 13 and took it to Mr. Quiggley’s Dead Dog Saloon, where it interacted with multiple people.  Because raccoons are rabies reservoirs, the raccoon had to be euthanized for testing. The rest of the litter was also tracked down and euthanized for testing, apparently, but that doesn’t make a lot of sense to me. If the raccoon to which people were exposed could be tested, that provides all the information that is needed from a rabies exposure standpoint. Maybe there was concern that other people would pick them up or maybe she put the baby back in with the litter after it’s trip to the bar and no one could tell which one it was. Regardless, the raccoons probably didn’t have rabies but the person’s actions led to their deaths.

Beyond rabies, there are a few other potential concerns:

  • Baylisascaris procyonis: The raccoon roundworm is very common, and it’s likely that eggs of this parasite were being shed in feces, or that the haircoat of the raccoon was contaminated with feces containing the eggs. The latter is the main concern because eggs that have been in the environment are the ones that can infect people. Infection in people is rare, but the parasite can cause very nasty neurological disease so it’s one to be aware of.
  • Leptospirosis: Raccoons are a host of Leptospira bacteria, which are shed in urine. Contact with urine isn’t uncommon when handling young animals, and urine that gets into cuts or the eyes, mouth or nose can result in transmission.

Hopefully not many people actually handled the critter and they washed their hands (but sometimes common sense is surprisingly uncommon).

Take home message: Leave wildlife in the wild.

Lyme disease: The Difference Between Knowing and Actually Doing…

Posted in Dogs, Horses

Lifetime LymeGuest blog by Dr. Michelle Evason, DVM DipACVIM (as well as current PhD student and coordinator of our Lifetime Lyme Study)

In 2014, the Public Health Agency of Canada (PHAC) initiated a 3-year marketing campaign (news, advertisements, social media, collaboration with Parks Canada to post signage, etc.) to try to raise the general public’s awareness and educate them on the topic of Lyme disease. This (Lyme) isn’t exactly a low profile subject… and it’s become increasingly high profile in the past several years. Particularly in Canada, where ticks appear to be giving raccoons a solid run for the title of top non-human vector of disease causing pathogens.

Interestingly (and fairly forward thinking in my opinion), two studies (see below) were performed to look at the level of Lyme awareness in canucks and secondarily to assess whether PHAC’s targeted educational media blitz had any effect on understanding of Lyme disease and subsequent behavior changes regarding tick prevention. I suspect the study group was hopeful things would indeed improve and it would be considered dollars well spent… although some of us tend to be cynics about that sort of thing (and yes, that is my idea of subtle foreshadowing). Cutting to the chase… a bit strangely (and sadly) Canadian respondents’ correct answers for prevention or reduction of tick attachment, i.e. avoiding wooded areas or mowing one’s lawn regularly, appeared to decrease over the course of the media campaign. In other words, there were more correct survey answers before the educational intervention than after the 3 years of media coverage. Also (again a bit depressingly), questionnaire respondents tended to answer incorrectly more often if they lived in a Lyme “higher risk” zone or location.

Fortunately (maybe?) most Canadians who participated in the studies appeared to know about Lyme disease and also what medical symptoms are associated with illness. So, the “raise awareness” box did appear to get checked – which is wonderful. However…this didn’t appear to translate into knowledge regarding how to protect oneself from actually getting Lyme disease, such as regular tick checks, wearing protective clothing or using tick repellent.

I’ve never understood why knowing something doesn’t translate into actively doing something about it. Granted I have developed a few theories over the years, and I’m positive my family would be pretty quick to say that I don’t always make the best choices even when I know better also, so glass houses and all that. On the other hand, Lyme disease gets an awful LOT of attention, and it seems like focusing some of that energy on preventing it from happening might be good? And I suspect that would be true for all animals at risk, not just the ones who bark or whinny most believably.

Aenishaenslin, C., Bouchard, C., Koffi, J. K., Pelcat, Y., & Ogden, N. H. (2016). Evidence of rapid changes in Lyme disease awareness in Canada. Ticks and Tick-Borne Diseases. http://doi.org/10.1016/j.ttbdis.2016.09.007

Aenishaenslin, C., Bouchard, C., Koffi, J. K., & Ogden, N. H. (2016). Exposure and preventive behaviours toward ticks and Lyme disease in Canada: results from a first national survey. http://doi.org/10.1016/j.ttbdis.2016.10.006