Worms & Germs Blog

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Polar Bears and Clostridium difficile

By Scott Weese on Posted in Other animals

And now for something completely different…

We’ve studied Clostridium difficile in my lab for years and we probably have one of the world’s most diverse collections of this important bacterium. We have thousands of isolates of the bacterium from people, pets, livestock and many different wildlife species (as well as from meat, vegetables and water).  Most of the focus on C. difficile involves human disease, something that makes sense because it’s a very important cause of serious gastrointestinal disease in people. It causes disease in some animal species, but in many, it’s there but doesn’t seem to ever cause a problem.

Looking at the genetic makeup of a bacterium, it’s possible to infer how old it is. C. difficile is pretty ancient. It’s been estimated that in emerged 1.5-85 million years ago (He et al, PNAS, 2010)

That’s well before humans (or potentially even mammals) emerged, so it’s clearly not a human-origin bacterium. Rather, it evolved in wildlife and certain strains have made their way into people.

That’s a long introduction for a paper we just published about C. difficile in polar bears (Weese et al, Anaerobe, 2019).

Why polar bears?

Usually, we do ‘hypothesis driven research”, where we come up with a specific answerable question or problem and try to investigate it.

Sometimes, we’re opportunistic and curious, with less of a real plan. Here, it was basically someone saying“we have polar bear poop….is there anything you’d like to do with it?” However, sometimes these curiosity-driven studies are rewarding.

Anyway…

…we got samples from a large study that was collecting polar bear feces from wild bears in the Canadian Arctic, bears temporarily housed in the Polar Bear Jail in Churchill, Manitoba (a facility where nuisance bears get shipped to for a while before being released back into the wild) and a few polar bears from a zoo.

Surprisingly, we found C. difficile in almost 17% of samples; 18/120 (15%) from wild bears, 4/7 (57%) from the polar bear jail and 2/16 (13%) from the zoo.

To be honest, my first thought when we had so many positive results was “crap, contamination…(pardon the pun)”. However, typing of the bacterium showed us differently. We found a variety of strains, but none that were found in the wild bears were the same as strains we’ve ever seen. Also, the strain distribution was different in bears from the M’Clintock Channel vs those from Hudson Strait, two different bear populations, despite the fact that the samples were all processed together in the lab. (That made me feel a lot better).

Were the polar bears sick?

It’s hard to say, but probably not. Fecal samples were collected off the ice or ground, not right from the bear (for pretty obvious reasons). Presumably, like most wildlife species, C. difficile can be present in the guts of polar bears without causing disease.

How do polar bears get this bacterium?

We’ve been able to find C. difficile in most species that we’ve studied.  That includes most livestock species, pet species and a range of wildlife, from raccoons to bats. It’s been found in seals (not in the Arctic, but I’m not aware of anyone looking there). Since seals are a common food source for polar bears, if the bacterium is present in seals in the Arctic, that’s a likely source of exposure.

This raises the question of whether C. difficile shedding polar bears pose a risk to people?

I guess. However, there are lots of ways that we can get exposed to this bacterium. It’s possible we get exposed to low levels of it most days. If you’re close enough to the polar bear to get C. difficile from it, you probably have bigger things to worry about.

Rabies in the News

By Scott Weese on Posted in Dogs, Rabies

I’m taking a Brucella break so here are a few interesting rabies stories.

More rabies in Nunavut

A rabies warning was issued to residents of Taloyoak, Nunavut in response to identification of rabies in ‘a number’ of dogs and foxes (I’m not sure what that number is).

It’s not new, and rabies is a concern is the territory. It’s also an issue for other areas in Canada since dogs are periodically shipped out of Nunavut into southern regions. Arctic fox rabies in endemic in the region and there is periodic spillover into dogs. Vaccination rates are variable in remote communities, increasing the risk. Multiple animals with rabies have been moved out of Nunavut in the past year to a couple provinces.

 

Skunk Bite Means Rabies Exposure

Skunks are a natural rabies reservoir in some regions, something that an Arizona man found out recently. He was bitten by a skunk, which was subsequently determined to be rabid. Why, exactly, he was close enough to a skunk to be bitten is another question, and one that wasn’t evident in the news articles I saw. I don’t think people need a reason beyond getting sprayed to stay away from skunk, but rabies is a good one.

 

Rabies Exposure Costs More Than A New Car

…depending on the type of car. A woman was bitten by a stray kitten she was trying to feed outside Everglades National Park (take home message #1…stay away from wildlife and stray animals). She underwent post-exposure prophylaxis at a cost of….$48512. (No, I didn’t misplace a decimal point). $46,222 of that was for the single immunoglobulin (antibody) injection. I don’t understand the US healthcare system but this seems crazy. It seems even crazier based on a statement that the cost would have “only” been $9900 if she was bitten a couple months later, after the hospital lowered its price. I guess someone made a nice profit off her rabies exposure.

 

Rabies Exposure from a Goat

Goats aren’t at the forefront of species I think about when someone says rabies, but like any other mammal, it can happen. A big concern about rabies in goats is the fact that they sometimes get handled by a lot of people. Recently, a rabid goat was identified in South Carolina, resulting in potential exposure of 9 people.

Brucella canis: Ontario

By Scott Weese on Posted in Dogs, Other diseases

This is another one of those “I can’t say much specific because of privacy laws but there’s so much social media paranoia that I have to say something.”

Is there concern about Brucella canis in Ontario?

  • Yes. We have been concerned about this bacterium for a while, particularly in imported dogs and commercial breeders (including ‘puppy mills’). I can’t comment on the current situation more than to say we are investigating and I’m concerned but far from panicked.
  • However, it’s probably not new. A recent study from Michigan reported a low (0.4%) infection rates in pet dogs but much higher rates in commercial operations (Johnson et al 2018) and a study of dogs is Mississippi shelters found Brucella rates ranging from 8-9% (Hubbard et al 2018). We know very little about Brucella canis in Canada, but it’s been here for a while.

Why is there a concern?

  • This bacterium can cause disease in dogs and people.  In dogs, most of the problems are reproductive, with abortions, stillbirths and reproductive failure. However, a variety of other consequences can occur.
  • Human infections seem to be rare but they may be underdiagnosed, as signs can be vague and brucellosis might not be considered.

Is Brucella in dogs treatable?

  •  We can use antibiotics but it’s difficult to get rid of the bacterium completely. It’s hard to be confident that the bacterium is actually gone. We end up having to periodically re-test dogs to see if there’s sign of it coming back. So, we can rarely say ‘yes, it’s definitely gone.”

Do all infected dogs need to be euthanized?

  • In kennels, euthanasia is most often performed because of the risks of continuing to produce infected puppies and the potential for animals to keep infecting each other. Spaying or neutering is also an important part of treatment (since the bacterium likes to live in reproductive tissues), and that doesn’t work for a breeding dog.
  • For pet dogs, that’s a case-by-case situation, depending on the disease, the household situation, risk averse, and sometime, based on Public Health requirements.

What can I do?

  • If you are getting a puppy, make sure you know the source. Puppies from large commercial breeders, puppy mills or poorly managed operations are highest risk because of how the dogs are sourced, managed and tested (or, specifically, not tested).
  • If you have a dog from an unknown source, you could consider testing. It’s hard to say that Brucella testing is needed for every pet dog, but it is reasonable to consider if the dog might have come from a higher risk area (Asia, Mexico, southern US) or breeder.

Is testing straightforward?

  • No. It’s a multistep procedure. Usually, we start with a screening test. If that test is positive, we follow up with a more specific test that is less likely to have false positive results. Then, we ideally follow up with a final test such as trying to culture the bacterium or detect its DNA. If the first test is negative, that’s great. If the dog might have been recently exposed, we’d ideally re-test in a couple months because it can take time for a dog to test positive after exposure.

Can my dog pick up Brucella in the park?

  • Odds of this are exceptionally low. They’re probably basically zero, but in the infectious disease world, we’re rarely brave enough to say ‘never’. Brucella canis is transmitted most often in kennel situations, through breeding and through infection of pups before birth. Transmission can occur in other dog contact situations (e.g. a dog living with an infected dog) but that likely requires longterm contact. Transient, casual contact poses little risk.

What about my dog?

  • Merlin came from a breeder that we know well. He’s exceptionally low risk to have come to us with Brucella. He’s neutered, reducing the risk further. He has regular casual contact with dogs at Heather’s workplace but I’m not worried about that type of contact. I don’t plan on testing him or losing any sleep over his Brucella status. If I had obtained him recently from a puppy mill in Ontario, from out of the country or from unknown sources, I’d consider testing.

Here are a couple good Resources:

Center for Food Security and Public Health fact sheet

American Kennel Club fact sheet

Echinococcus multilocularis in a Child: Quebec

By Scott Weese on Posted in Deworming, Dogs, Parasites

The whole situation with Echinococcus multilocularis, an important zoonotic tapeworm from dogs, is evolving and unclear in Canada (and probably the US). It’s becoming increasingly clear that the parasite is present in a high percentage of wild canids (e.g. coyotes, foxes) in some regions. What this means for human health isn’t clear yet.

Echinococcus multilocularis is a small tapeworm that lives in the intestinal tracts of canids. People can become infected when they inadvertently ingest parasite eggs from canid feces. In people, the parasite can migrate to tissues such as the liver and cause lesions very similar to cancer. Treatment can be difficult and, untreated, mortality rates are high (approaching 100%). One problem with sorting out Echinococcus infections in people is the long incubation period. It can take 5-15 years from exposure to development of disease. That’s good in some ways, but it also means that detection of changes or new problems can be a challenge.

One question we have, as we find this parasite in new areas, is what that means for people. Reporting of human cases can be variable, and even if reported, the long incubation period means that it takes a long time to identify changes. So, if we’re seeing a big change in risk to people from a change in this parasite in canids, we may not know for years. Lack of human cases is sometimes cited as a reason that it’s not a big deal. However, this comes down to the ‘absence of evidence’ vs ‘evidence of absence’ debate.

A recent case in Quebec heightens some concerns. Echinococcus multilocularis infection was identified in a child, and it was believed to have been acquired locally. The child had not travelled outside of Quebec, and the dog they had previously owned was from Quebec.  Foxes were a possible source since they were common in the area and exposure to fox feces in the outdoor environment was considered likely. However, differentiation of exposure from a pet dog or environmental exposure to canid feces is impossible.

One case does not make an epidemic. However, it’s one more piece in the puzzle. Ongoing work looking for this parasite in pet dogs will help figure out the risk…more to come on that as the year progresses.

More information about Echinococcus multilocularis can be found in our Resources section.

Rabies in developing countries

By Scott Weese on Posted in Dogs, Rabies, Vaccination

We often talk about rabies in the context of high GDP countries, focusing on wildlife rabies and exposure during travel. However, in many parts of the world, exposure to canine rabies is an ever-present risk, and there can be substantial barriers to getting proper post-exposure prophylaxis (PEP) when needed. That’s part of the reason tens of thousands of people still die every year from canine rabies.

A recent paper in Clinical Case Reports (Audu et al. 2019) describes two cases of human rabies in Nigeria that highlight some of these challenges:

  • The first person was a 40-year-old man who was bitten by a stray dog. The dog was killed by people in the community but not tested for rabies. He went to a local health clinic where he got a tetanus shot and antibiotics, but no rabies PEP because they didn’t have any. He was referred to another facility about 100 km away, but chose not to go. Rather, he tried a traditional treatment that involved eating the liver of the biting dog and putting hairs from the neck of the dog on the bite wounds. Two months later, he developed signs consistent with rabies and died.
  • The second person owned a puppy that developed rabies. The puppy had bitten her and two neighbours and was confirmed as rabid after it died. Neither the puppy nor its dam had been vaccinated. The neighbours received PEP but the owner declined because of the cost. Five weeks later, she developed signs consistent with rabies and died.

These represent just two of the thousands of people who died of rabies in 2017, but their stories are not unique.

Getting people to go to a doctor after a dog bite is the first challenge, and education of the public is needed to make that happen. However, it doesn’t help if there is then no access to rabies PEP. Traditional treatments are sometimes used because there’s no alternative, but they are also sometimes used instead of available and highly effective conventional treatments. Vaccination of dogs is a useful rabies control tool but has limitations in areas where canine rabies is endemic and where feral dog populations are large. The target is vaccination of 70% of dogs, and groups such as Mission Rabies have done a lot to help hit that target. However, rabies will continue to circulate in many regions. Vaccinating pets, the animals that have the closest contact with people, is important but is not often done in some areas because of cost, failure to recognize the need and lack of access to vaccines.

Costs of seeking healthcare and rabies PEP can be a substantial barrier. In case 2, the cost was ~$68 USD (much less than the exorbitant $48000 that was recently charged to one woman in the US for rabies PEP), but even that was unaffordable to the victim.

The solution to the rabies epidemic isn’t straightforward. Education of the public, veterinarians and healthcare providers, improved healthcare access, reduced cost of treatment and more widespread vaccination of dogs are important but can be challenging. There’s no simple solution to the problem, but economic development (facilitating education, healthcare, transportation and drug access) is a big component. Barring that, education and vaccination efforts are critical.

New infographics: Echinococcus multilocularis, feline upper respiratory tract infection

By Scott Weese on Posted in Cats, Dogs, Other diseases, Parasites

The title says it all… see below for the latest and greatest infographics from the Ontario Animal Health Network, including an update to the very popular E. multilocularis infographic and a new one on treatment of feline upper respiratory tract infection.

 

To download the infographics in pdf format, visit oahn.ca at these links:

Treatment of feline upper respiratory tract infection

Emerging risk: Echinococcus multilocularis in Ontario

 

Brucella canis in imported dogs: Ontario

By Scott Weese on Posted in Dogs

I’ve been holding off on this post because the situation is still evolving, but there’s enough of a rumour mill developing (and I’m getting enough emails from concerned people) that I thought I should respond.

A little background:

  • Brucella canis is a bacterium that can cause a variety of issues in dogs (particularly reproductive issues), and can also be transmitted to people.
  • While it’s rare (well under 1%) in pet dogs in Canada and the US, it’s more common in dogs from commercial breeding operations (e.g. puppy mills) and dogs from certain parts of the world.
  • We don’t see infections in dogs here very often.  When we do, most of the time (but not always), it’s a dog that came from somewhere else.
  • B. canis is hard to treat and it’s hard to have confidence that it’s been eliminated from the dog after treatment, even if visible signs of illness have resolved.
  • It can also be spread to people. However, human infections seem to be rare and close, direct contact is likely required for transmission.
  • The greatest human risk likely comes from contact with female dogs that have aborted or recently given birth (whelped), since the bacterium can be present in high numbers in fetal and reproductive fluids and tissues.

Current situation in Ontario:

It’s my fault, I guess, since we’ve started screening imported dogs for disease surveillance as part of a research project. If you don’t look, you don’t know. If you do look, sometimes you end up revealing a complicated situation.

It wouldn’t really be surprising to find B. canis in a small percentage of imported dogs, since foreign, intact (i.e. not neutered or spayed) dogs are a higher risk group for infection to start. So, it isn’t a shock that we have identified some suspected and presumptive cases in recently imported dogs. Diagnosis of B. canis infection isn’t always straightforward either, so it’s tough to be definitive at this stage.

Testing of healthy dogs involves use of a screening test (RSAT) to start. This type of test has a high sensitivity (it will pick up a very high percentage of infected dogs) but a lower specificity (some dogs that aren’t actually infected will test positive too, these are known as “false positives”). Dogs that are positive on the screening test are then tested again using other tests to try to confirm the diagnosis. So far we have one dog that was positive on the second test. We have some others that were positive only on the first screening test. That could be because there was a cross-reaction and they are actually false positives, or it could because they were only very recently infected, or because the follow up tests aren’t as sensitive. With that type of result, we consider them suspicious and typically recommend trying other tests or repeating the testing in a month or so.

Take home messages (at this point):

  • 1 dog with B. canis infection is a concern but it’s not overly surprising. A lot of infected dogs would be more of a problem. We’re trying to sort out which scenario this is.
  • With infectious diseases, it’s best to err on the side of being overly cautious at the start and take extra precautions initially, while things are being sorted out. Sometimes we look back and realize we didn’t need to do all those things based on the final result, but it’s better than not doing enough at the start and then trying to play catch-up later.
  • The risk to the general dog population is very low. Close and direct contact with an infected dog is required for transmission to either other dogs or people.
  • The current situation is likely lower risk than many other situations, such as people buying dogs that came from puppy mills or other imported dogs where no one is looking at their disease status at all.
  • The groups with which we are working are taking a proactive approach to make sure problems don’t develop or spread.
  • Knowing is better than not knowing, even if it sometimes causes confusion or concern at first.

More information will follow, and if there’s a significant risk to the broader dog or human population, I’m not one to hold back saying that. At this point, people shouldn’t worry.  For more information on B. canis in dogs and the associated public health risks, a review of the topic was recently published in Emerging Infectious Diseases.

Revised ISCAID guidelines for diagnosis and treatment of urinary tract infections in dogs and cats

By Scott Weese on Posted in Cats, Dogs

Hot off the press… the newest edition of the International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats has been published in The Veterinary Journal. These are updated and expanded clinical guidelines that have been in the works for the past couple of years, as a followup to the initial 2011 guidelines. They are meant to be open access (i.e. free to download), but there have been issues for some readers who were unable to download them to date – we’re looking into it.

New imported distemper strain in dogs

By Scott Weese on Posted in Dogs, Other diseases, Vaccination

Here’s a report from Cornell University’s Animal Health Diagnostic Center, describing importation of a canine distemper strain that hasn’t been found before in North America:

02/05/2019: (N. America) In early October of 2018, a 12-week old “Sheltie” arrived from Korea. Approximately 12 days later, the dog began with a cough and lethargy with blood work indicating “anemia”. About 10 days later, the dog developed a unilateral myoclonus with relapsing lethargy. In another week the neurological signs had progressed to tonic clonic seizures that continued to worsen to a persistent uncontrolled myoclonus at which time the dog was euthanized.

Samples (serum, ocular swab, urine) obtained at 9 days post onset of clinical signs were forwarded to the AHDC for canine influenza virus serology and canine distemper virus RT-PCR testing. The HI serology test indicated no exposure to H3N2 CIV which is the endemic strain of flu A in Korea. However, the RT-PCR tests on the ocular swab and urine were strong positive for canine distemper virus. Attempts were made to isolate the virus from the samples submitted for PCR, but with no success. Our next effort was to try to obtain sequence for virus directly from the nucleic acid used for the RT-PCR assay. This was successful for the F and H genes of CDV. Phylogenetic analyses of the sequences against various clades of CDV, indicated the imported dog was infected with the Asia-1 strain of CDV. We have no information on the existence of this clade of CDV in North America.

While we have been most concerned with the importation of canine influenza virus from Asia to North America by improper procedures by various “rescue” groups, the importation of CDV may be more significant in that CDV once it enters an ecosystem cannot be eradicated even with effective vaccines. Once again the North American dog population is being put at risk by those who have no regard for the importation of foreign animal diseases.

Drunk raccoons?

By Scott Weese on Posted in Rabies

Rabies and distemper are the two things that come to mind first when a raccoon is acting strangely. Rabies is a big concern because it can also be transmitted to people. Distemper is also a viral infection, caused by canine distemper virus, and is transmissible to dogs and some wildlife species, but is not zoonotic. Raccoons are very susceptible to distemper and infections and outbreaks are common. If raccoon rabies is present in the area, we need to err on the side of caution and treat an abnormal raccoon as potentially rabid until proven otherwise. If raccoon rabies isn’t in the area, an abnormal raccoon is generally assumed to have distemper (but remember that rabid raccoons can hitch rides on vehicles, so we can’t rule out rabies completely without testing).

But there is one other possible cause for a raccoon to be acting somewhat drunk… alcohol.

A story from last fall (yes, I’m a bit slow) in the Washington Post describes a rabies scare in West Virginia, where the raccoons were ultimately determined to have been intoxicated by alcohol. No, they hadn’t raided a liquor store – it turns out they’d been eating fermented crab apples.

Surprisingly (and good to hear), they weren’t euthanized right away because of their abnormal behaviour. Just like we do for any other drunken mammalian species, the raccoons were held until they sobered up, and were then sent on their way. A picture of one of the young offenders was released by the Milton (W. Va) Police Department. It’s much cuter than the typical mug shot.

Drunk or not, it’s still a good idea to stay away from raccoons, especially in southern Ontario.