Worms & Germs Blog

Worms & Germs Blog

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Brucella canis updates: US dogs, Canadian person, and lots of Canadian dogs

By Scott Weese on Posted in Dogs

Brucella canis is getting a lot of attention these days, and taking up more of my time than I ever would have thought a few months ago.

Identification of infected dogs linked to a commercial breeder in Iowa (also see our previous post from Tuesday) has attracted a lot of attention. It’s hard to say how noteworthy it is, because we know the bacterium is present in some commercial breeding (puppy mill) operations and in imported dogs. It’s of particular concern because it can be transmitted to people, but we don’t know how much of a concern that is or how often it occurs. It seems to be rare, but it can occur (more on that in a minute).

The Iowa situation is still being sorted out, but may pale in comparison to what’s going on in Ontario. We detected Brucella canis in some imported dogs earlier this year, in a group of dogs imported from South Korea (positive dogs from the same region (possibly the same shipment) were later identified in the US as well). That caused a big stink at the time, but settled down.

Of greater concern is the more recent identification of Brucella canis in commercial breeding dogs in Ontario. We have over 100 known or suspected positive dogs (testing is a bit of a pain for this bacterium, to say the least), and since we certainly haven’t tested all (or even most) commercial breeding dogs in the province, it’s reasonable to assume that the true number of affected dogs is much greater.

So, what’s the risk to people?

  • We don’t know. It’s a rarely diagnosed disease in humans. The problem is that could be because it’s a rare disease, or because it’s an under-diagnosed disease. It’s probably a combination of both. It seems to be truly rare, but human infections do occur. The greatest concern involves kids, as they’re more susceptible to infection and severe disease, but it can affect others (see below).
  • As we’ve worked through the Ontario situation, my impression has been the overall risk to people is probably still quite low (dogs may be another story). Otherwise, we should have seen a reasonable number of sick people in Ontario. The lingering concern is whether there are infected but as of yet undiagnosed people in the province.

A recent report from of a British Columbia woman who was diagnosed with brucellosis highlights this concern. The woman had non-specific signs including fever, headaches and weight loss for two months before the diagnosis was reached. The link was believed to be a pregnant dog from Mexico (a place from where Brucella-infected dogs have originated before) that spontaneously aborted two stillborn puppies while being transported by the woman in question, who regularly helps move rescue dogs from the US and Mexico. That dog tested positive for Brucella canis and contact with aborted fetuses, fluids and other tissues would be high-risk for transmission of the infection to the person.

One case doesn’t mean it’s a big problem, but it means there’s concern. Here are a few take home messages:

  • Brucella canis is of greatest concern in imported dogs and dogs from commercial breeders.
  • If you purchased a dog from an internet source, pet store or anywhere else where you don’t have very clear information about the background of the dog, testing for Brucella is a reasonable idea.
  • If you are importing dogs or have adopted an imported dog, you should consider testing for Brucella, especially if it came from Asia, Mexico or eastern Europe.
  • All breeding dogs should be tested for Brucella at least once a year.
  • You shouldn’t freak out about Brucella because human infections seem to be rare, but you should be aware of it.
  • Dog owners should make sure their physicians know that they have dogs (as for any pet) and physicians should be aware of the zoonotic potential of Brucella canis.

For more information, check out the OAHN factsheet on Brucella canis for veterinarians and our archives.

Canine brucellosis international, factsheet for veterinarians

By Maureen Anderson on Posted in Dogs, Other diseases

Recently another couple of good examples have cropped up of the risks of canine brucellosis (caused by Brucella canis) associated with both canine breeding kennels and international movement of dogs.

The state veterinarian for Iowa confirmed that there were several cases of brucellosis diagnosed in dogs from a small breeding facility in Marion County.  Officials are attempting to reach any individuals who may now have a dog that could have been exposed at the facility, which is now under quarantine, and further testing is underway.  The same article mentions another breeder in Knoxville, Iowa that also had dogs that tested positive, and a local adoption service that purchased 32 dogs at auction at now has the entire group under quarantine while the dogs are tested.

Across the pond, in the Netherlands (a country known for its strict and typically quite effective infection control measures), Brucella canis was diagnosed in a domestically-bred dog for the first time, but ultimately the dog had international ties.  The case was discovered when a male dog from the breeding kennel that was originally imported from Russia was examined for back pain.  The dog was tested and found to be infected.  The cause of the back pain was likely discospondylitis, which is one of the well-recognized manifestations of brucellosis in dogs beyond reproductive issues.  The positive result prompted testing of other dogs at the facility, and one of the animals that had been born in the Netherlands was also found to be infected (not surprisingly).  All of the dogs at the facility were ultimately euthanized after consultation with government officials and the owner.  Officials are also doing everything they can to track down anyone who adopted a dog from the kennel to advise them of the risks and hopefully prevent further spread.

It’s important for veterinarians, dog breeders and owners to be aware of the risks of canine brucellosis, as it can infect both dogs and people.  It is especially important to be careful about imported dogs, or those with limited medical history that could have come from a high-risk facility.  The Ontario Animal Health Network (OAHN) has produced a handy factsheet on Brucella canis for veterinarians to help navigate the issues, and particularly the diagnostic testing process which involves several different kinds of tests.

More information about B. canis can also be found in our archives.

Itchy dogs: Topical treatments and culture-critical cases

By Maureen Anderson on Posted in Dogs

The latest companion animal infographic from the Ontario Animal Health Network (OAHN) is now available!  Currently the network is working on a series of infographics focused on good antimicrobial stewardship.  Stewardship includes knowing when NOT to use antimicrobials, and what to use when antimicrobials are needed.  Guidance is available from leading veterinary infection control experts, through the open-access ISCAID Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (Hillier et al. 2014).  Click here to download the infographic in pdf.

The infographic is a handy visual reminder of things to think about when dealing with some of these itchy dogs as the weather warms up.  You can also find more infographics and resources on www.oahn.ca.  If you are a veterinarian or technician, you can sign up for the quarterly companion animal OAHN report, and also help contribute to disease surveillance in Ontario through our 5-minute clinical impressions survey once every quarter!

Small animal infectious diseases, and how they get around

By Maureen Anderson on Posted in Cats, Dogs, Other diseases

The latest issue of Veterinary Clinics of North America: Small Animal Practice includes a number of chapters on infectious diseases that have been making regular appearances on this blog, including rabies, influenza, brucellosis, Lyme disease, and more, as well as chapters on certain feline-specific infectious diseases.  Check out the full table of contents and summaries here.

While we can’t provide direct access to the full content of the issue, we worked directly on two of the chapters (along with our colleague Dr. Jason Stull from The Ohio State University) and are therefore able to share the author links to the sections on the dynamic nature of canine and feline infectious disease risks in the 21st century, and the impact of dog transport on high-risk infectious diseases.  These links will be active until June 22, 2019, after that access will only be by subscription (institutional or otherwise) or purchase.  If you can, we encourage you to check out the other great content in this issue as well!

US ban of importation of dogs from Egypt

By Scott Weese on Posted in Dogs, Rabies, Vaccination

Effective tomorrow, the US Centers for Disease Control and Prevention (CDC) has suspended importation of dogs to the US that:

  • are from Egypt, or
  • originated in Egypt and have been in another country for less than 6 months.

This is being done because of multiple cases of rabies in imported dogs specifically from Egypt over the past few years (including some with falsified vaccination certificates). Despite rules for high risk countries like Egypt, rabid dogs can still slip into the country because of ineffective vaccines, fraudulent health records and the potentially long incubation period of this disease.

Banning dogs travelling directly from Egypt will be straightforward. Banning dogs that have recently been in Egypt will be more of a challenge. For example, if they go to another country considered high risk for canine rabies, they’d need to get a new rabies vaccination certificate (hopefully along with a valid vaccine!) from that country, otherwise the Egyptian certificate would give away their recent origin. It’s a somewhat surprising step since regulation and restriction of dog importation tends to be low priority, but it’s good to see.

Let’s see if other countries (yes, I’m talking about you Canada) follow suit, since a large number of dogs are imported into Canada from Egypt every year.

Rat bite fever on Vancouver Island, Canada

By Scott Weese on Posted in Other animals, Pocket pets

When I talk to veterinary and public health audiences about zoonotic diseases, I often talk about rat bite fever because it highlights some common issues that are important to keep in mind.

Usually, I start by presenting a case of a child with a fever and rash.

Then, I mention that someone finally asked about pets and they reported a rat bite.

Then, I say “what does the kid probably have?”

  • And I get… blank stares 95% of the time.

Then I say “the kid had a rat biteand has a fever… what is it?”

  • More blank stares (some are probably asleep, admittedly).

Then I say “rat bite fever [pause]… seriously, that’s the name of the disease.”

  • Still some blank stares (and the odd snore).

Beyond showing the limited awareness of this disease, the cases in which I get involved have a few common themes:

  • The bite is rarely reported initially. It’s not usually until the person gets referred to a specialist that someone asks about pet contact. “Has your child had any animal contact?” is an easy question to ask, but it rarely gets asked, in my experience. So, the opportunity for early diagnosis is missed.
  • The important issue of zoonotic disease risk and risk acceptance that go along with pet ownership or animal contact. Pretty much all rats harbour the bacterium that causes rat bite fever (Streptobacillus moniliformis), so every rat poses some degree of risk. The risk can lowered with good handling practices (to avoid bites) and proper bite first aid. Rat ownership can still be relatively low risk with some common sense, but it’s never zero.  People handling or owning rats need to be aware of the risk and how to mitigate it.

Anyway, that’s a long lead-in to a recent paper on rat bite fever in Canada (Hryciw et al, Can Commun Dis Rep 2018).

It’s a recap of 11 cases on Vancouver Island between 2010 and 2016

  • All affected people had pretty typical disease: fever and one or more of muscle pain, rash, joint pain, swollen joints or vomiting.
  • Everyone recovered, but seven patients were hospitalized.
  • Both bites and scratches were implicated as the source. Scratches are a potential source if they become inoculated with rat saliva at the same time.
  • All reported rat contacts were from pet rats.
  • Not much more about the rats or bites was reported.

There wasn’t too much remarkable in the paper overall, but it’s another good reminder about this disease and the need to report (patients) and query (healthcare providers) history of pet contact when someone is sick.

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

Oral rabies virus exposure

By Scott Weese on Posted in Dogs, Rabies, Vaccination

Rabies is “almost always” transmitted by bites and “almost invariably” fatal once disease develops in a person or animal. We use a lot of these kinds of disclaimers with infectious diseases, which can be frustrating, but it’s necessary because exceptional (strange) things occasionally occur.

A report in an upcoming edition of Emerging Infectious Diseases (Zhao et al). describes an unusual case of rabies in a man from China.

The man was from a village in Jiangsu province, China, where canine rabies is endemic. His son was bitten by a stray dog, which is absolutely considered a potential rabies exposure unless the dog is caught for quarantine or testing. Family members provided wound care, which is important, but as part of this treatment the man in question tried to suck “toxic blood” from his son’s wounds.

Neighbours killed and buried the dog, so it couldn’t be tested for rabies, but the son got appropriate medical care and received post-exposure prophylaxis (PEP). The physician also recommended PEP to the father, because of the potential that he could have been exposed to rabies virus in saliva from the dog that had been deposited in the wound. However, he declined, in part because of cost and because of his belief that he had spat out all the blood.

Approximately a month later, the man developed signs of rabies, and died the day after he was hospitalized. His son was fine.

While control of rabies in areas where it is widespread in the dog population is challenging, preventing rabies in people is actually straightforward. Rabies PEP is “almost always” effective (another waffly term, but failure of properly administered PEP is incredibly rare, if it even occurs). But things fall apart when there is poor education (e.g. the bite victim or healthcare providers not understanding the need for treatment), lack of access to treatment or economic barriers. Here, two of these were involved in this man’s death: while healthcare providers recognized the risk and made the appropriate recommendation, the man declined because of a lack of understanding of the risk and because of cost concerns. These factors resulted in his death as much as the dog itself did.

Happy Easter from Finnegan and Merlin (well… maybe not so much Finnegan).

Echinococcus multilocularis back in the news

By Scott Weese on Posted in Deworming, Dogs, Parasites

Nothing has changed about Echinococcus multilocularis (the fox tapeworm) in the past couple of months, but my phone is ringing off the hook following another round of media reports about this parasite. Here’s a recap of the issues:

  • Echinococcus multilocularis is a small tapeworm normally found in the intestinal tract of wild canids (e.g. coyotes, foxes) and sometimes dogs. For these animals, having this worm in the gut doesn’t cause a problem. The main concern is when something (or someone) ingests tapeworm eggs that are passed in feces of these canids.  This can result in a condition called alveolar echinococcosis (AE), in which tumour-like parasitic cysts can develop in other parts of the body, particularly in the liver.
  • In the normal (wildlife) life cycle of this tapeworm, wild canids shed eggs in their feces which are eaten by small rodents, that then develop AE. When a canid eats an infected rodent, the parasite grows into its adult stage in the canid’s gut and produces more eggs, and the cycle continues.  While that’s bad for the rodents, the bigger problem is that this “intermediate host” stage can occur in more than rodents… including dogs and people.
  • Alveolar echinococcosis has been diagnosed in a small number of Ontario dogs (with little to no travel history) since 2012, raising questions about how they got infected. The concern was that this parasite had become established in our wild canid population, which presents an ongoing risk to people and other animals, and is very hard to control.
  • Human cases in Canada are rare but are being found and may be underdiagnosed.  Since AE is a very nasty disease, and very difficult to treat, we’re inherently cautious.

The recent news stories picked up on a study published earlier this year in Emerging Infectious Diseases (Kotwa et al 2019), where an astounding 23% of wild canids in Southern Ontario were found to be shedding Echinococcus multilocularis. 

What’s the risk to dogs in Ontario?

  • We don’t know. I realize that’s not comforting but it’s the honest answer. We should know a lot more in the next few months as we test samples from pet dogs in the highest risk areas. Until then, it’s hard to say much with confidence.

What should dog owners do?

There are two main approaches to prevention: decreasing the risk of exposure and prophylactic treatment.

We can treat dogs for tapeworms, but this isn’t usually part of routine deworming protocols, so only a small percentage of dogs are treated on a regular basis. I’ve been treating my dog with praziquantel monthly for the past couple of years, since emergence of the parasite was identified, because we’re in a higher risk area and he will eat anything. We live in the country and have a lot of coyotes around. If the parasite is here, it’s quite plausible he would be exposed.

The risk is much lower (or non-existent, potentially) in other regions, and dogs that have less outdoor access are much lower risk. Quantifying that risk is the challenge.

Ultimately, whether or not to treat a dog prophylactically is a case-by-case decision, based on the dog’s risk factors (and the owner’s risk aversion).

More information about Echinococcus multilocularis can be found on the Worms & Germs Resources – Pets page. Also check out emultiontario.com and the updated infographic from the Ontario Animal Health Network.  We’ll provide updates as more information about this parasite becomes available.

Linezolid resistance in dogs and cats

By Scott Weese on Posted in Cats, Dogs

A recent presentation at ECCMID (European Congress of Clinical Microbiology and Infectious Diseases) in Amsterdam described a series of linezolid-resistant enterococci in dogs and cats in the UK. I’m only able to get information from media reports, so details are limited (and potentially lost in translation); however, it’s an interesting story. It’s unsurprising in many ways, but highlights some important issues.

Linezolid is an antibiotic that’s typically used in human medicine for infections caused by multidrug-resistant Gram-positive bacteria such as staphylococci (including MRSA) and enterococci. It’s rarely used in veterinary medicine, but has been used in dogs and cats for the same types of infections. Because it’s one of few options for treatment of MRSA in people, it’s an important drug, and resistance is a significant concern.

The UK story involves a cluster of infections at one veterinary clinic. Enterococci that were resistant to linezolid were found in two cats and one dog. They were found to carry a gene, optrA, that confers linezolid resistance.  This is the first time this gene has been found in a bacterium from a companion animal in the UK. optrA is found on a plasmid, a small piece of DNA that can be move relatively easily between bacteria, meaning it can potentially spread to other bacteria of the same species, or even to those of other bacterial species. There are no details in the reports I’ve seen about timing of the infections, and whether the cluster in the clinic was likely due to direct contact between animals, contact with a contaminated environment or contact with people who were either contaminated (e.g. carrying the bug on their hands from touching an infected animal or contaminated surface in the clinic) or colonized (i.e. people who harbour the bacterium in their intestines and can be a source of contamination themselves).

Where did the linezolid-resistant enterococci originate?

It’s hard to say from the limited information I’ve seen. It could have come from a person, as there are lots of instances of humans infecting their pets with a variety of bacteria. That’s largely how MRSA originates in dogs and cats, and other resistant bacteria that are common in humans have entered the pet population in this way.

Use of linezolid in animals should not have played a role. Articles have stated that linezolid is not used in dogs and cats in the UK, and while I question whether that’s actually true, linezolid use is so rare to non-existent in pets that there’s probably no realistic risk of emergence of resistance from use of that drug in these species. However, optrA doesn’t just confer resistance to linezolid. It also confers resistance to chloramphenicol and florfenicol, drugs that are (uncommonly) used in dogs and cats. This highlights the “co-selection” issue, when the use of one drug can select for resistance in other drugs. I suspect a human source is more likely here but it’s hard to say.

According to one article, the authors indicated “Our findings further the ‘One-Health’ view that antibiotic-resistant bacteria can be shared by animals and humans, although the direction of transfer is often difficult to prove. We currently do not know the prevalence of linezolid-resistant enterococci in companion animals and therefore a joint approach to monitoring emergence and dissemination of resistance mechanisms of public health importance is needed”, says Dr. Hopkins. “In this instance, further transmission was stopped by cleaning and decontamination and we have no evidence that any people acquired an infection from these animals.”

What this means in the big picture is hard to say, but it shows how resistant bacteria and resistance genes can move between and within species, sometimes in unexpected ways. It also shows how the common bug-drug-species focus (i.e. looking at one type of resistant bacterium in just one (human or animal) species) can miss the big picture. Antimicrobial resistance is a complex ecological problem that requires a complex and comprehensive approach, which is currently still lacking.