Worms & Germs Blog

More Ontario Echinococcus multilocularis cases

Posted in Dogs

BoxerThis tiny parasite continues to cause a stir around Ontario. While infections are (apparently) still rare, it’s becoming clear that this nasty worm has somehow stealthily established itself in the province. That presumably means it’s either also in neighbouring provinces and states, or heading there.

Echinococcus multilocularis is a small tapeworm that can cause severe disease. Canids (dogs and wild canids like foxes) are the “definitive hosts,” and when infected these animals can shed tapeworm eggs in their feces. Normally, these eggs are eaten by small rodents, who then develop tumour-like lesions containing an immature life stage of the parasite.  Canids then get infected by eating the infected little critters, and the cycle continues.

The normal life cycle of Echinococcus is a problem for the rodents but not for the dogs, because having these tapeworms in just the intestine doesn’t cause any signs of illness.  If that’s all there was to the story, it wouldn’t get much attention, but the issue is that other species can develop the tumour-like disease similar to the rodents. This includes people, in whom serious and very difficult-to-treat disease can develop, typically after a very long (5 to 15 years) incubation period .

Now what’s happened is there have been several cases in Ontario of these tumour-like lesions in dogs. While dogs are usually intestinal carriers of the adult tapeworm, they can also occasionally develop these lesions from the immature tapeworms instead, if they swallow large numbers of tapeworm eggs (just like rodents and people) . We’ve now seen 4 cases of this since 2012.  Based on what we know of the parasite’s epidemiology in other parts of the world, we know that infections like this in dogs tend to only develop in regions where the parasite is widespread in wild canids. That suggests we might have a big, silent reservoir out there, and that human cases could be on the horizon.

Time will tell.

More information about the latest case, along with a few pictures, can be found in the latest Animal Health Laboratory Newsletter.

More information about Echinococcus multilocularis and other tapeworms is available in the Worms & Germs archives and on the Worms & Germs Resources – Pets page.

Fall Fair Fowl Factsheet – Biosecurity for poultry at shows

Posted in Birds, Other diseases

Fancy chickenPoultry biosecurity is an important practice to limit the spread of disease. There are many viruses, bacteria and parasites that exist that can cause disease in birds. These can spread by direct bird contact or indirect contact with humans, housing and equipment. Some of these pathogens can be zoonotic and pose a human health risk. Pathogens of concern include Salmonella, E. coli, and avian influenza.

Highly pathogenic avian influenza (HPAI) H5N2 was diagnosed in 3 commercial poultry flocks in Oxford County, Ontario in April 2015.  The control zones in the affected area were finally removed at the end of July, but 3 months of post-outbreak surveillance need to be completed before Ontario can regain its HPAI-free status.  Poultry producers, feather fanciers and those with backyard birds also need to be on alert HPAI with fall approaching, because migratory birds could bring the virus back again.  Biosecurity is critical to keep HPAI out of domestic birds, and particularly to reduce the risk of transmission to commercial flocks.

Shows and competitions, whether they’re for livestock or pets of almost any species, are perfect venues for disseminating infectious diseases.  Bring together a large number of animals (and people!) from lots of different places, in a relatively stressful environment and small space, add a pathogen and you can have a widespread outbreak in no time.

The solution (or at least the best way to reduce the risk as much as possible, short of not having the show) is good infection control practices by everyone (exhibitors and visitors alike).  The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) has therefore produced an infosheet on poultry biosecurity for fall fairs, including what to do before, at and after the show.  Everyone has a role to play, and the chain is only as strong as its weakest link, so please do your part to help protect the poultry industry. These measures can also help to protect people from avian influenza.  So far we’ve been lucky in North America that the HPAI strain we’ve had was not highly contagious to people, but flu viruses are constantly changing so it’s important to stay vigilant.

More Pasteurella in the news

Posted in Cats, Dogs

Hip replacementThe Canadian Journal of Infectious Diseases and Medical Microbiology has been good, recently, for a zoonotic disease article or two. The latest edition has a report of Pasteurella multocida infections of prosthetic joints (Lam et al. 2015). Pasteurella multocida is a bacterium that’s commonly found in the mouths of dogs and cats, and can cause infections in those species, as well as people, if given the right opportunity. That usually occurs after a bite, but can also occur in other situations, particularly when animal saliva is involved (e.g. licking).

The report describes a complicated case in which a women had a hip replaced, then developed a series of infections of the surgical implant over the following 8 years. These were caused by a variety of different bacteria.  As is often the case, the decision was made to remove the implant because elimination of infections on foreign materials in the body can be very difficult. She underwent a surgery to remove the artificial hip, then was put on a course of antibiotics prior to a planned surgery to put in a new hip. It was during this in-between period that the latest infection developed, and she was taken to surgery to clean up the infected site. Samples collected during surgery yielded Pasteurella multocida, which lead to some questions about animal contact (better late than never?). She lived with 5 dogs and 2 cats, and the dogs had been allowed to lick a wound on her leg. Fortunately, she was treated successfully and got her new hip a couple of months later.

As part of the case report, the authors reviewed the literature and found 32 published cases of P. multocida prosthetic joint infections. That doesn’t mean there have only been 32 infections ever – presumably many more have occurred and not been published. So, it’s a rare issue but it does occur. Some of the highlights of their review:

  • 22 cases involved cats while 10 involved dogs.
  • 26/32 were in women.
  • Old age and a few things associated with compromised immune systems were commonly present.
  • Most cases occurred months to years after surgery but shortly (days to weeks) after animal contact. That’s probably a bit of a dodgy statement though, since rarely do people have just one defined animal contact. If someone has a dog, they probably have contact with the dog most days – if they develop an infection after surgery it would be impossible to discern which contact on what day actually led to infection. Their last contact might have been days to weeks before the onset of disease, but that doesn’t mean that’s when they were infected.

Some practical concluding statements in the paper were:

It is important for clinicians to ask about animal exposure when evaluating a patient with a PJI, particularly if the infection has occurred remote from the surgery [i.e. the infection developed a long time from of surgery], so that the appropriate empirical therapy can be chosen. … In light of the case presented here, it is reasonable to counsel patients about the risk for zoonotic infections of surgical wounds and the steps that can be taken to potentially reduce this risk, such as maintaining good hand hygiene after pet contact, keeping wounds covered, avoiding direct pet contact with any unhealed, uncovered or open wounds, and reporting all significant animal-induced wounds to a physician.”

On a (somewhat) related note, a boy from Idaho was recently diagnosed with meningitis caused by P. multocida. The poorly written news article doesn’t provide much information or anything about animal contact, but I have to assume there was an animal source.

New USEF equine vaccination requirements

Posted in Horses, Vaccination

Mandatory vaccination for horses entering shows, other events and sales has been a surprisingly contentious issue for years. Some groups have required equine influenza vaccination for a long time, and it’s an accepted measure. Attempts to mandate vaccination for some other groups or events have often been met with resistance, even when those attempts were made after major disease outbreaks. Among the main arguments against vaccination requirements are:

  • Domesticated 0226It’s expensive: However, in the grand scheme, it’s a miniscule amount of the cost of raising a horse. Most of the time, the gas to get to an event probably costs more than the vaccine.
  • It doesn’t work: No vaccine is 100% effective, but flu vaccines are reasonably good, especially when applied at the population level. By that I mean that when you have a large percentage of the population vaccinated, you decrease the risk of virus transmission and help protect horses that are unvaccinated or didn’t respond to the vaccine.  (This is also called “herd immunity.”)

Often, it’s really just resistance to change that drives opposition.

However, the US Equestrian Federation (USEF) has just announced a new mandatory vaccination policy. As of December 1, 2015, all horses entering a USEF show must have been vaccinated against equine influenza and equine herpesvirus in the past 6 months.

As reported by TheHorse.com, “This rule change and uniformity of rules is going to help us not only better protect our horses against infectious upper respiratory diseases, but it also will improve the welfare of these show horses,” [Chair of the USEF veterinary committee, Dr Kent] Allen said. “It is important for every owner, as well as the entire USEF organization to ensure that each horse is adequately protected through appropriate vaccination.”

“The bottom line is your horse must be current on the equine influenza and equine herpesvirus vaccines by 1 Dec 2015,” he said. “If you maintain this vaccination schedule and obtain appropriate documentation, you will not only comply with the rule, but you also will ensure your horse is adequately protected against these highly contagious respiratory diseases.”

Hopefully other organizations will follow. I’m sure there’ll be lots of complaints, but that’s the nature of progress.

West Nile virus in Ontario

Posted in Horses, Vaccination

Fed mosquitoThe season has arrived. Right on schedule, the first case of West Nile virus (WNV)  infection in an Ontario horse has been identified, prompting an advisory from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). The affected horse was from Sudbury, Ontario, and was euthanized because of progressive and severe neurological disease. It had not been vaccinated against WNV.

Presumably, this is just the start of at least a few cases in the province, although there was only one reported case last year.  Vaccination of horses can provide protection against the disease, but it takes time to respond to a vaccine, so vaccinating now may not provide protection for at least a few weeks.  This is especially true for horses that have never been vaccinated before because they need two doses of vaccine about 3 weeks apart (called a “primary series”) to be protected.  But, remember that no vaccine is 100% protective, so it’s also important to avoid the mosquitoes that transmit the virus by taking precautions like staying inside at dusk and dawn and using insect repellant – precautions that apply to horses and their owners alike.

Equine strangles persistence

Posted in Horses

Horse lip curlThis week, a horse show in Halifax (UK) was cancelled because of some local cases of strangles (Streptococcus equi subsp equi infection). We can debate whether that was prudent or overkill (or whether measures could have been put in place to reduce the risk and make it manageable), but it highlights the concerns that accompany infections caused by this bacterium.

Strangles outbreaks are, in some ways, easy to control, and in others, quite difficult. Realistically, in my experience, when people can and will do what I recommend during an outbreak, it’s readily contained. Where things go off the rails is when people are unwilling to listen, only do a half-hearted job of infection control measures, are unable to control horse movement, or start well but lapse back into old habits too early.

Anyway, that’s not the point of this post. When dealing with cases on farms, the question of what to do about the outdoor environment often comes up. Horses can pick up the bacterium from contaminated objects or surfaces (even the ground), so if an infected horse deposits S. equi in a paddock or pasture (i.e. in nasal secretions or pus), what’s the risk to other horses and what can be done?

On a recent ProMED-mail posting about this horse show, a widely circulated but outdated line of “Under ideal environmental circumstances, the organism can survive 7-9 weeks outside the host. Paddocks and barn facilities used by infected horses should be regarded as contaminated for about 2 months after resolution of an outbreak.”

Firstly, the reference that was cited (the Merck Veterinary Manual) doesn’t actually say this (anymore). Rather, it now says “Survival of the organism in the environment depends on temperature and humidity; it is susceptible to desiccation, extreme heat, and exposure to sunlight and must be protected within mucoid secretions to survive. Under ideal environmental circumstances, the organism can survive ~4 wk outside the host. Under field conditions, most organisms do not survive 96 hr.” (updated January 2014)

That’s a more reasonable approach, and it’s presumably based on some research we did a few years ago (Weese et al, Can Vet J 2009) that showed the bug dies very quickly (often within a day) when outside, exposed to sunlight and other stressors.

That doesn’t mean someone with a strangles case on a farm should immediately open up potentially contaminated areas to unexposed horses. But, 2 months is quite excessive. Realistically, each scenario is different and a risk assessment based on the type of exposure, surface materials, ability to keep pastures/paddocks closed and local weather (including temperature and exposure to sunlight especially) are used to make a reasonable estimate of how long to quarantine outdoor environments. It’s never perfect but almost always it can be well under 2 months with little risk.

H3N2 influenza in a cat?

Posted in Cats

Cat washingIn what would be an interesting but not completely surprising twist, there’s a report of H3N2 influenza infection in a cat from a New York city shelter. The report’s pretty limited in detail, and it’s not clear to me how solid the diagnosis is, but it would be interesting if true. It probably doesn’t represent a major concern or change in the virus. Rather, it’s likely reflective of an uncommon spillover into a different species.  Spillover hosts typically aren’t able to effectively pass the virus on, so it would be a rare event and not an indication the virus has changed or is going to spread among the cat population.

But, as ever with flu, time will tell.

Canine importation editorial

Posted in Dogs

Burning questionClick below for an editorial that appeared in the July 2015 edition of Clinician’s Brief.

Clinician’s Brief Canine Importation Editorial

It asks some very to-the-point questions about why dogs continue to be imported in massive numbers into some regions (including Ontario), despite the animal and public health risks.  The issue is slowly gaining recognition, particularly with events like the recent canine influenza outbreak in the US.  Hopefully the recognition will ultimately lead to action, but there are many groups (such as animal owners, veterinarians, and government to name a few) that will need to be involved.

Yet another influenza in dogs

Posted in Dogs

Dog nose B&WThis latest flu strain probably isn’t as big a deal as some other influenza viruses found in dogs, but it demonstrates that it’s important to monitor influenza in different species and look for changes.

A paper published ahead of print in Emerging Infections Diseases (Lin et al, Dec 2015) describes an H6N1 influenza virus in dogs in Taiwan. This strain of influenza A has been widespread in chickens in Taiwan for decades, and rarely have infections with this type been found in mammals (which is a good thing). This study involved collection of samples from pet dogs presented to a University teaching hospital as well as from free-roaming rural dogs. Blood samples were tested for the presence of antibodies against influenza. Nasal swabs were also collected from dogs presented to the teaching hospital with signs of respiratory disease, to look for the virus itself.

  • Antibodies against flu virus were identified in 3/281 (1.1%) pet dogs and 6/193 (3.1%) strays. Antibodies against H6N1 were confirmed in one of these animals.
  • More interesting was results of testing for the virus itself. Influenza virus was detected by PCR (a test that looks for genetic material from the virus) in 4/185 (2.1%) dogs. All of these dogs had nasal discharge or cough. Three were young (<6 months of age). Three were also what I’d consider higher-risk: two were strays adopted from the streets and one was adopted from a shelter.
  • Virus culture was attempted and influenza virus was grown from one sample, a 4-month-old puppy that also had distemper.
  • Interestingly, serial blood samples did not detect any antibodies against the virus in this dog. Maybe that’s because the pup was too sick to respond to the infection, but it shows that infection may occur in the absence of detectable antibodies (the test that is often used for surveillance studies).
  • When the genetic sequence of the cultured virus was assessed, it was confirmed as H6N1, and 99% similar to H6N1 from chickens in Taiwan. That’s not surprising at this was likely a spillover event from chickens or other birds into the dog.

Fortunately, this H6N1 influenza strain (currently) poses little risk to people. The fact that it can infect dogs, and maybe cause disease (that wasn’t really confirmed, as the dogs could have had some other respiratory disease) does raise some concern.

This study should be yet another reminder of the unpredictable nature of influenza and the need to include domestic animals, including dogs and cats, in influenza surveillance.