Worms & Germs Blog

Colistin Resistance in Pets

Posted in Cats, Dogs

DNA helix2I’ve had a lot of emails over the past few months from colleagues from other countries, asking if we’re finding much mcr-1 in Canada. mcr-1 is a gene that makes bacteria resistant to colistin, a “drug of last resort” in people with some highly resistant infections.  The gene has emerged in bacteria from both animals and humans. It’s also been found a few times in a couple of different types of bacteria from food animals and food products in Canada.

This gene probably originated in food animals and is likely distributed in farm animals internationally, although only recently have researchers starting testing for it. I’ve been interested in the pet side, particularly following a report last year of mcr-1 in multiple dogs and cats in a Chinese pet store (after infection of a pet store employee was identified). When there was a large shipment of rescue dogs from China to Canada late last year, I would have loved to have tested some of the animals for mcr-1 in the bacteria they were shedding, along with various other things (for example, we know that multiple cases of distemper were associated with that particular group of dogs).

A recent paper in Emerging Infectious Diseases entitled mcr-1in Enterobacteriaceae from companion animals, Beijing, China, 2012-2016 highlights these concerns.

In that study (Lei et al, 2017) they tested Enterobacteriaceae from healthy and sick dogs and cats from Beijing’s Veterinary Teaching Hospital of the China Agricultural University. Enterobacteriaceae is a group of Gram negative bacteria, including most notably E. coli, Enterobacter, Salmonella and Klebsiella. The results were a bit scary:

  • 14% of the 566 isolates tested were resistant to colistin. This was mainly in E coli and Klebsiella.
  • 62% of the colistin-resistant isolates harboured mcr-1.
  • Bacteria that possessed mcr-1 were typically resistant to many other antibiotics, but were susceptible to some drugs.
  • Many different strains were involved, showing that this gene has moved to lots of different bacteria that have dispersed in the population.
  • 7/35 pet food samples (primarily chicken-based) were positive for mcr-1. What this means is unclear. Testing was done by PCR, which detects DNA, not necessarily live bacteria. So the bacteria containing mcr-1 could have been killed in cooking. But wow – that’s a concern, and further suggests that this gene may be highly prevalent in food animals.

Why was the colistin resistance rate so high? That’s an interesting question, since colistin is not used to treat dogs and cats (as opposed to food animals in some regions). It could reflect widespread exposure from food and the environment. It could also reflect use of other antibiotics in pets, since use of any drug to which the bacterium is resistant can select for that bug, and all its genes (e.g. if a bacterium is resistant to ampicillin and colistin, use of either drug will select for it).

What’s the threat to pets? Pretty minimal, since we don’t use colistin in pets.

What’s the threat to people? That’s the big question, since sharing of mcr-1 ­containing bacteria can definitely occur. The main concern is that pets might be a reservoir of mcr-1-carrying bacteria in households and the community. More work needs to be done to assess this risk, and look at mcr-1 in various species in other countries.

Immunocompromised People and Their Pets

Posted in Birds, Cats, Dogs, Other animals, Pocket pets, Reptiles

Cat on bed2This month’s edition of the Internal Medicine Journal contains an article entitled High rates of potentially infectious exposures between immunocompromised patients and their companion animals: an unmet need for education (Gurry et al. 2017). The study is fairly superficial and there’s nothing particularly surprising in the paper, with results similar to what has been reported in the past (including one of our earlier studies on high risk children (Stull et al. 2014)). The sad part, perhaps, is the conclusion that there is a need for increased education of patients – something that’s been said many times before but with little resulting action.

Here are some highlights from the study, which surveyed 265 adults with a few types of disorders that would increase their risk of infection.

  • 52% owned an animal. That’s pretty consistent with other studies and what we know about pet ownership in general. High risk people tend to have the same ownership patterns as the general public.
  • Dogs and cats were the most common pets, but other species were also reported. 3% owned reptiles, which are  very high risk pets for immunocompromised individuals.
  • 30% of individuals reported having been bitten or scratched by their animal at some point. This probably poses the greatest risk for most pet owners (beyond reptile owners, where Salmonella is the main concern).
  • Close to half allowed their pet to sleep on/in the bed. That’s gotten a lot of attention in the past and I really don’t get too concerned about it in most situations. (On the bed is also different than in the bed, or sleeping right against your face.)
  • Only 17% recalled getting some information from healthcare workers about safe practices around their pets. If anything, that’s probably higher than average, showing a major gap that needs to be filled.

I think most people would agree that we need better education for high risk people about pets and zoonoses. How to actually get that done is the challenge.

Seoul Virus in Ontario

Posted in Pocket pets

RatsIt’s not particularly surprising, I guess, but a few cases of Seoul virus infection have been identified in Ontario residents who breed or have contact with rats.  Fortunately, like most infections with this type of hantavirus, disease was mild. Equally not surprising is that infected rats have been found in Ontario rat-breeding facilities.  The Ministry of Health and Long-Term Care is investigating the source of the virus, including any possible connections to the ongoing outbreak of Seoul virus in the US, which has resulted in 16 confirmed human infections to date.  It’s another reminder of the ever-present risk of emerging or unusual diseases, and that risks increase when animals are moved around the country or planet.  Seoul virus can be transmitted from rats to people via contact with urine, feces or saliva (so wash your hands after handling rats and avoid kissing them!), but there is no evidence that it can be transmitted from person to person.  More information for Ontario veterinarians is available in the OMAFRA Veterinary Update posted on OAHN.ca.

Flesh Eating Disease with a Pony Link

Posted in Horses

Shetland ponyThe bacterium Streptococcus equi subsp. zooepidemicus (often simply called Streptococcus zooepidemicus) is one that I think I understand less and less, including the risks this predominantly equine-associated bug poses to humans. It’s a well-known and common bacterium in horses, both healthy and sick, and can also be found in dogs and cats (where it can cause serious disease). Despite what has to be very common and sometimes abundant exposure in equine personnel in particular, human disease is rare. Yet, disease can occur. It seems like it’s being reported more often in the medical literature, but whether that’s because human infections are becoming more common or just more commonly identified and written about is a big question.

A recent case report entitled “Zoonotic necrotizing myositis caused by Streptococcus equi subsp. zooepidemicus in a farmer” (Kittang et al, BMC Infect Diseases 2017) once again shows the potential for nasty human infection.

The affected person was an otherwise healthy 73-year-old farmer who owned two healthy Shetland ponies. He was admitted to hospital with pain in his groin. His condition deteriorated and a CT scan identified suspected necrotizing myositis (flesh-eating disease). Emergency surgery was performed to remove the infected tissue in this case, as this type of bacterial infection is so severe and rapidly progressive that the best chance of survival is for the infected tissue to be removed ASAP – antibiotics alone are unlikely to to be effective. Culture of the affected tissue yielded S. zooepidemicus. Thirty days, two surgeries and lots of very intensive care later, the patient was discharged from the hospital. Rapid diagnosis, initial administration of antibiotics that were effective against the bacterium and most importantly, rapid surgery, were probably the most important factors in this successful outcome.

The link to horses is through the nature of the bacterium and not any specific investigation. Since S. zooepidemicus is a horse-associated bacterium and the man had contact with ponies, the potential link is obvious. However, the bacterium can also be found in other animal species, so it’s still only a presumptive link. As is typically (and unfortunately) the case, swabs of the ponies were not taken to see if the same bacterial strain could be identified.

How the man was infected isn’t clear. He reportedly had some minor abrasions and blisters on his fingers at a time when he was handling the ponies. So, it’s possible the bacterium from respiratory secretions of a pony got into the wounds and spread to the muscles in his thigh. That’s a pretty oddball occurrence for minor skin wounds and healthy horses. Considering the number of horse personnel that have skin wounds at any time, this highlights the potential but presumably exceptionally low overall risk. The man’s age probably increased his risk of infection, but other reasons why he (and not the large number of other people similarly exposed to horses on a daily basis) got sick are not obvious.

Does this change anything?

  • Not really. We’ve known that S. zooepidemicus can cause disease in people for a long time. This type of infection is different but not overly surprising. It’s another reminder of the ever-present potential of exposure to zoonotic pathogens from healthy animals.

What should be done?

  • A little hygiene goes a long way. Keeping wounds covered and washing potentially exposed sites are probably the best preventive measures when working around apparently healthy animals. That’s particularly true for people at increased risk of disease, such as people over 65 year of age, young children, pregnant women and people who have a compromised immune system.

So, don’t run screaming next time you get horse slobber on your hands, but don’t forget to wash your hands.

Canine and Feline Respiratory Infection Treatment Guidelines

Posted in Cats, Dogs, Other diseases

Dog cough SSThe latest set of clinical treatment guidelines from the International Society for Companion Animal Infectious Diseases have been published in the Journal of Veterinary Internal Medicine (Lappin et al 2017): Antimicrobial Use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases.

It’s available via the link above or through the JVIM website.

Rabies and Bite Responses

Posted in Dogs, Rabies, Vaccination

There tends to be confusion about what happens when an animal bites or is bitten, and rabies is being considered. Most of the confusion revolves around how long an animal is quarantined or observed. Yet, it’s actually pretty straightforward if you think about why quarantine/observation is being performed and some basics about the virus and the disease itself.

Scenario 1: A dog bites a person

This one’s easy.

  • The response: 10 day quarantine or observation. Basically, we need to ensure that the dog is normal 10 days after the bite.


  • To see if it develops signs of rabies. Based on the nature of rabies virus infection, by the time a dog is infectious (shedding rabies virus in saliva) the infection is well advanced. If the dog is neurologically normal 10 days after the bite, it could not have had rabies virus in its saliva at the time of the bite

What if the dog was vaccinated against rabies?

  • That doesn’t have any impact. Vaccination is highly effective but not 100% protective. Since you can’t guarantee a vaccinated dog doesn’t have rabies, even vaccinated dogs may be placed under a 10-day observation period.

Raccoon doubleScenario 2: A dog is bitten by a raccoon (or other potentially rabid animal)

One variable here is whether the offending animal is available for testing. If it is killed/euthanized and tested, and shown not to have rabies virus in its brain, the bitten dog is in the clear (same applies if a person is bitten by a wild animal).  In a large proportion of cases the offending animal is not available for testing, and the rabies status of the animal is never known at the time of the bite.

Why is there a response?

  • Unlike scenario 1, the goal here isn’t to see if the dog was incubating rabies virus when it was bitten. The goal is to determine if there is a reasonable risk that the dog will develop rabies, and to keep it contained during the period when rabies is most likely to develop so it can’t infect someone else. The incubation period for rabies in dogs can be long (months) so the quarantine/observation period has to be longer.

What is the response?

  • The first step is to perform a risk assessment to determine the likelihood that the offending animal transmitted rabies to the dog.  Although the risk from a bite from another mammal is never zero, if the risk is deemed to be very low then no specific action is taken other than to ensure the dog’s vaccination status is up-to-date.  Pet owners must always be vigilant for neurologic signs in their animals that may be consistent with rabies.  Even indoor animals can have contact with potential rabies vectors such as bats.
  • If the risk assessment is that there is a significant risk of rabies transmission, unlike scenario 1, the dog’s vaccination status then plays a role in determining the subsequent response. (Note: These rules are for Ontario. There’s some variation between jurisdictions).

If the dog was full vaccinated, according to the intervals specified by the vaccine manufacturer, and is not overdue for a booster:

  • The dog still requires a rabies booster is given within 7 days of the bite.  If this is done, there is no confinement period, although an informal observation period (45 days) is recommended out of an abundance of caution.
  • If a booster isn’t given within 7 days, then the dog gets a 3 month precautionary confinement period (PCP). During this time, they have to stay on the owner’s property (except for medical care), have contact only with one caregiver, have no contact with other animals, can only go outside on a leash and in a fenced area and must be cordoned off when inside with a double barrier (e.g. kept in a room with a closed door in a house with a closed door).

If the dog received an initial rabies vaccine but is not yet due for its first booster (i.e. within 12 months but no less than 14 days after initial vaccination):

  • Same as for fully vaccinated dogs. The key is getting to booster done within 7 days.

If the dog has been vaccinated in the past but is overdue for a booster:

  • This is handled on a case-by-case basis, thinking about the time since vaccination, the number of vaccines the dog has had in the past and other things that might influence protection. Usually, the response is a booster within 7 days and a 3 month PCP. Without a booster, a 6 month PCP is used.

If the dog has never been vaccinated against rabies or rabies vaccination history is unknown:

  • If the dog gets a rabies shot within 7 days of the bite, it gets a 3 month PCP. If not, it’s 6 months. Euthanasia is the other option and is sometimes chosen because of the issues with long quarantines. That’s particularly true with puppies (who are more likely to be unvaccinated), where long confinement periods can be very difficult and impact socialization.

Incidentally, the same rules apply to cats in Ontario. Don’t forget, all dogs, cats and ferrets over 3 months of age in Southern Ontario are legally required to be fully vaccinated for rabies at all times.  Failure to do so can result in a fine (which usually costs more than the vaccination!)

2016 Rabies Compendium

Posted in Cats, Dogs, Horses, Other animals, Rabies, Vaccination

Vampire smileyThe 2016 Compendium of Animal Rabies Prevention and Control has been released by the US’s National Association of State Public Health Veterinarians (NASPHV). This version has updates in a few different areas, such as some changes to recommendations for dogs, cats and ferrets that have potentially been exposed to rabies. It can be downloaded directly here or be found with other documents at the NASPHV Compendium site.

Is MRSP zoonotic?

Posted in Dogs, MRSA/MRSP

three-dogsI’ve written about this many times (probably because I get asked about it almost every day), but there’s not really a simple answer to the question “Does methicillin-resistant Staph. pseudintermedius pose a human health risk?

My typical answer is along the lines of “Yes, but…” with discussion about how rare Staph pseudintermedius (SP) infections are in people, despite widespread exposure to infected or colonized dogs. However, “low” doesn’t mean “no.”

A recent article in Vector-Borne and Zoonotic Diseases (Lozano et al 2017) describes methicillin-susceptible SP infections in four people. The first question you might have is, why would I talk about susceptible SP in the discussion of MRSP?  It’s relevant because they’re still the same bug – being methicillin-resistant doesn’t make SP more likely to infect a person, but it does make it harder to kill if it causes an infection (which is why it’s a concern). Therefore, understanding aspects of susceptible SP infections is useful in understanding MRSP.

Here are some highlights from the study:

  • Infections were diagnosed in four people in a hospital in Spain over a 10 month period. All four patients had what sounds like relatively straightforward skin and soft tissue infections. Two of the four people were higher risk (one with cancer and one described generically as being immunocompromised).
  • One patient had a surgical site infection and no contact with animals. Not much more is said about this one but is raises questions about where it might have originated.
  • Patient 2 had contact with dogs, but did not own any herself. Patients 3 and 4 both owned dogs.
  • SP was isolated from the 3 dogs owned by patients 3 and 4. That’s not surprising since we can find SP in most dogs at any given time.
  • The same SP strains were found in dogs and infected people within the same households. That’s also not surprising since the dogs were the logical source and we’ve previously shown that when we find S. pseudintermedius in people in households, it’s usually the same strain as in their pet. Most likely, we interchange SP and various other bacteria on a regular basis.

In some ways, this is just a straightforward but nicely documented small series of SP infections in people. It doesn’t change the answer to the “Is MRSP zoonotic?” question that I’ll probably get (again) at some point over the next couple of days. However, it re-inforces the low but ever-present potential risk posed by this bacterium, like many other bacteria that dogs carry.

One final comment to hopefully put things into perspective: When talking about MRSP risk, a statement I often make is “If I had to rank the top 5 zoonotic risks posed by a dog carrying MRSP (or plain old SP), MRSP/SP would probably not make that list.” It’s worth paying attention to MRSP, but at the same time, it’s important to keep it in perspective, realize how rare it is, realize how basic measures probably reduce that risk even further, and remember that all dogs pose some (very low) degree of risk, and we’re better off thinking about routine practices rather than focusing on low risk bugs like this.

For me, this report is just one more reason to emphasize the overall message: the risk is low but you never want a multidrug-resistant infection so you should use some basic infection control and hygiene measures to reduce exposure to MRSP. Most of that is easy, revolving around avoiding contact with infected site (eg. skin infections), avoiding contact with the nose, mouth and feces of dogs with MRSP infections (since they are often carrying the bug at those sites as well) and good old handwashing.

Seoul Virus in Pet Rats

Posted in Pocket pets

White ratAnother day, another new zoonotic disease concern.

Well, it’s not really that bad, but the list of new (or at least newly identified) zoonotic disease issues continues to expand at an impressive rate.

One of the latest concerns is a cluster of Seoul virus infections linked to rats. At last report, 8 infections with Seoul virus have been identified in people in two US states.

Seoul virus is a member of the Hantavirus family, a group of viruses that lives primarily in rodents.  Seoul virus infections in people tend to be relatively mild. Most people who are infected do not develop any signs of disease, but flu-like illness and potentially some more serious complications such as kidney disease can occur. Relatively speaking, it’s much less serious than the life-threatening hantavirus pulmonary syndrome that can develop with other hantavirus infections, but it still warrants attention.

The first reported human case in this series was a at-home rodent breeder in Wisconsin. He ended up in hospital after developing fever, headache and some other vague flu-like symptoms. A family member subsequently tested positive as well. Fortunately, both recovered.

Since this is a rodent-borne virus, tracebacks to facilities from which this person obtained rats were pursued. Six additional human cases were identified associated with two rat-breeding facilities in Illinois. Efforts are ongoing to see if there are any infections in other people who purchased rats from any of these facilities.

One thing that was overlooked in this outbreak report is how the index case was identified. There’s not much information available, but Seoul virus testing isn’t routine, and testing of people with flu-like disease for things beyond influenza (if that) isn’t that common. A CNN news report about the Seoul virus outbreak said “Because of the patient’s exposure to rodents, the doctor had a “hunch” to test for hantavirus, explained [Director of the Wisconsin Dept of Health Services Bureau of Communicable Diseases Stephanie] Smiley.”

  • That’s an important point to me, as it shows that animal contact was queried (which unfortunately isn’t often done) and the information led to consideration of uncommon problems. We need more of this kind of behaviour to improve diagnosis of zoonotic diseases.

CDC’s recommendations for rat owners are pretty straightforward (and are what we tell rat owners to do at all times, since they also help reduce the risk of things like rat bite fever (Streptobacillus moniliformis infection)):

  • Wash your hands with soap and running water after touching, feeding, or caring for rodents, or cleaning their habitats. Be sure to assist children with handwashing.
  • Be aware that pet rodents can shed germs that can contaminate surfaces in areas where they live and roam. Make sure rodent enclosures are properly secured and safe, so your pet doesn’t get hurt or contaminate surfaces.
  • Clean and disinfect rodent habitats and supplies outside your home when possible. Never clean rodent habitats or their supplies in the kitchen sink, other food preparation areas, or the bathroom sink.
  • Avoid bites and scratches from rodents. Be cautious with unfamiliar animals, even if they seem friendly. Take precautions when cleaning out rodent cages or areas with rodent urine or droppings.
  • Visit your veterinarian for routine evaluation and care to keep your rodents healthy and to prevent infectious diseases.

If bitten by a rodent:

  • Wash the wound with warm soapy water immediately. Even healthy pets can carry germs.

Seek medical attention if:

  • Your pet appears sick.
  • Your wound is serious.
  • Your wound becomes red, painful, warm, or swollen.
  • Your last tetanus shot was more than 5 years ago.
  • You develop sudden fever or flu-like illness within 1-2 weeks after being bitten

Tell your healthcare provider that you have been around pet rodents, whether at home or away from home, especially if you are sick or have been bitten or scratched.

Rabies from a mongoose bite

Posted in Other animals, Rabies, Vaccination

Yellow mongooseEvery few days, it seems, I get an email or call that goes something like “I was just bitten by [insert various mammals here]. Do I need to worry about rabies or do anything?”

The answer’s pretty similar every time. While the relative risk posed by different animal species in different geographic regions varies, you have to think about rabies anytime you’ve been bitten by a mammal. Knowing what to do can save a lot of hassles, and maybe your life. While the likelihood of rabies exposure from a bite in most countries is very low, ignoring or not being aware of this low risk leads to deaths.

CDC’s Morbidity and Mortality Weekly Report Recently published an article about a rabies death in Puerto Rico from 2015 (Styczynski et al 2016). The affected person was a 54-year-old man who initially presented to the ER with fever, difficulty swallowing, tingling in a hand, cough and chest tightness. He died the next day. Upon further investigation, his wife reported that he had been bitten by a mongoose approximately 2 months earlier. However, he did not seek care for the bite. Rabies was confirmed on autopsy. After an investigation of his contacts, seven family members and two healthcare personnel received rabies post-exposure prophylaxis (PEP).

Mongooses are a rabies reservoir species in certain areas, and rabies is very common in mongooses in Puerto Rico. An astounding 97% of mongooses that were tested after biting a person between 2005-2008 were positive for rabies. Not surprisingly, rabies PEP is recommended after mongoose bites, as it is for bites from other rabies reservoir species (e.g. raccoons, skunks, foxes, bats) in other regions.

If this bite had been reported, it’s virtually guaranteed that the man would have received PEP, and with that, it’s virtually guaranteed that he would not have developed rabies. There are a number of reasons why people don’t get appropriate care following a bite from a potentially rabid animal. In some regions, it’s because of poor access to medical care, or little to no supply of the rabies vaccine and rabies antibodies required. That’s not the case in Puerto Rico, where failure to obtain treatment is much more likely due to lack of the victim knowing it’s needed.

As the authors conclude, “Public health measures to reduce the risk for human rabies should include increased resources for primary prevention, including routine pet vaccination (canine rabies in Puerto Rico results from transmission from mongooses) and pre-exposure prophylaxis for persons at highest risk. Community education should highlight measures to avoid bites from pets and wildlife. Effective oral rabies vaccine baits targeting mongooses might also be considered as they become commercially available. Interventions should focus on areas with known human-mongoose contacts, as determined by overlaying bite surveillance data and population density. Secondary prevention measures should be aimed at increasing awareness of the need for medical evaluation and PEP after any mongoose bite.”