Worms & Germs Blog

Anti-vaccination and a fatal disease from horses

Posted in Horses, Other diseases, Vaccination

Being an equine vet in some parts of Australia (namely Queensland) is scary… to the point that people are leaving equine practice or refusing to treat certain cases. That’s because of Hendra virus, a bat-associated virus that infects horses and which can spill over into people. It hasn’t infected many people, but it is most often fatal, and it can be transmitted through regular kinds of occupational exposures when working with horses.

This disease is a good example of what can be done with vaccination. Even though it’s a small market, being a disease confined to one region of one country, a vaccine was developed and regulatory hurdles were lowered to get it to market as quickly as possible. That likely saved horses lives, and probably some human lives too in the process.

Yet, not everyone is as happy about the situation.  Despite a disease that is among the most deadly in terms of the percentage of infected people who die, there’s an anti-vax movement related to Hendra vaccine for horses. I’ll skip the synopsis, but click here to read the whole story about the situation on TheAtlantic.com. It’s worth a read, regardless of whether you’re in Queensland or have horses.

Image: Flying foxes are a type of large fruit bat found in Australia that can carry Henra virus and transmit it to horses.

Canine Leishmania map

Posted in Dogs

One of the first diseases that really hit home for me in terms of concerns about canine importation and travel was leishmaniasis. This nasty parasitic disease is something I certainly didn’t learn about in vet school, and it wasn’t on my radar at all until I started getting calls for help managing infected dogs.

As part of our new international disease mapping initiative, here’s our first Leishmania map. As with the other maps, it will presumably evolve over time as we get more information (including reports from readers). Soon, we’ll have the maps on a separate post or page for quick reference for all our mapped diseases, but for now, this map is below and you can click here for the interactive version.

Ontario hits 10 000 dRIT rabies tests since 2015

Posted in Other animals, Rabies

Today’s post comes from Rachel Gagnon, Rabies Science Transfer Specialist with the Ontario Ministry of Natural Resources and Forestry (MNRF), highlighting some of the amazing work being done in Ontario in the ongoing battle against wildlife rabies.

Ontario’s rabies control program is a world leader when it comes to controlling and eliminating rabies. The MNRF program was successful in eliminating the raccoon variant of rabies from Ontario in 2005 and has been highly effective in keeping the current rabies outbreak – which started in 2015 – contained to within about 50 km of the original case. The Ontario rabies program also reduced an epidemic of fox strain rabies from 46,000 cases (from 1957 – 1986) down to 0 by 2012 through the implementation of the large scale rabies program which began in the 1990s.

To control and eliminate rabies from Ontario, wildlife are vaccinated by two methods; trap- vaccinate-release, and by distributing oral rabies vaccine baits. Where these management techniques are used is informed through surveillance testing of dead or sick animals, enabling cost effectiveness response. The blend of these key elements is what has made the rabies program a success in the past and presently.

During the most recent Ontario outbreak, which began in December 2015, the MNRF implemented a new cost-effective test developed by the Centers for Disease Control (CDC) to assess large volumes of rabies samples in wildlife quickly and accurately. The method, called the direct Rapid Immunohistochemical Test or dRIT, has allowed for a new approach to assessing the most recent outbreak in Ontario. The MNRF has been using dRIT in conjunction with the Canadian Food Inspection Agency’s (CFIA) direct fluorescent antibody test (FAT), which has long been considered the ‘gold standard’ of rabies testing, but requires expensive fluorescence microscopy and specialized lab equipment. In contrast, dRIT uses a significantly more economical light microscope and can be done in relatively simple lab spaces. dRIT has allowed MNRF to test more animals and get results quickly and accurately to better assess the size and spread of the rabies outbreak and to make effective management and control decisions. [Image: MNRF staff test wildlife samples in the lab.]

This test has been a game changer in the global work of rabies control, and has played an important role in assessing where rabies is present and how it is moving across the landscape here in Ontario. As of May 2018, MNRF tested its 10,000th sample using dRIT, enabling Ontario to achieve unprecedented detail in the monitoring of the current rabies outbreak. During this most recent outbreak, 393 of the 405 (97%) rabies cases in Ontario have been discovered by the MNRF lab through the dRIT method.

When MNRF began implementing the dRIT test, knowing the accuracy of the test results was crucial. Beginning in 2016, research was conducted to validate Ontario dRIT test results against gold standard FAT results. In the study, agreement between rabies positive dRIT and FAT results was 98.8% and agreement between the tests for rabies negative samples was 100%. MNRF staff have since implemented two changes related to staff training and diagnostic determination, and have since been able to achieve 100% agreement of positive results between both tests.

Each week, the MNRF lab receives an average of 85 samples for testing from within the rabies surveillance area. Numbers will fluctuate depending on the time of year. The rabies surveillance zone is a buffer zone of 50 km around any rabies cases. Targeted mammal species found dead in the zone can be submitted to MNRF for rabies testing.

MNRF tests animals each week by creating a tissue impression of available brain tissue onto a microscopic slide. These slides are put through a series of chemical baths, and incubated with a rabies specific stainable antibody. Slides are viewed by light microscopy to determine the results. A negative test slide would show as all blue, if rose-red round masses are detected the sample is diagnosed as positive. Once MNRF has completed their testing, positive samples are shipped to the Canadian Food Inspection Agency for secondary FAT confirmation. [Image: left – positive dRIT result showing red specific staining; right – negative dRIT result.] When new cases of rabies are detected, MNRF notifies partners in the Ontario Ministry of Health and Long-Term Care, Ontario Ministry of Agriculture, Food and Rural Affairs and local public health units who will conduct follow-up investigations to ensure no members of the public had been exposed to the rabid animal. Rabies maps are also updated on the MNRF website weekly to reflect the number and locations of the new cases. [The maps are also reposted on the OMAFRA rabies website and on the OAHN website.]

Though human deaths from rabies in Ontario are rare, it is still a major global problem. The World Health Organization states that tens of thousands of people die each year from rabies, most often through canine exposure. dRIT was developed by the Centre for Disease Control and Prevention to provide a means to test animals for rabies in developing countries, where funding and infrastructure would prohibit the traditional standard and more expensive test. dRIT has proven to be such an important tool for the diagnosis of rabies cases all over the world that the test has very recently been approved as an official diagnostic test by the World Organization for Animal Health General Assembly.

For more information about rabies in Ontario, the rabies program, and to see updated maps visit the Ontario.ca rabies website.

Canine and feline antiparasitics

Posted in Cats, Dogs, Parasites

Negotiating the world of antiparasitics for dogs and cats can be daunting. With the wide range of products, similarly named products with different ingredients and differently named products with the same ingredients, it’s hard to keep up.

The Ontario Animal Health Network as put together some useful tables that outline antiparasitic products available in Canada and the parasites for which they have label claims.  There is a simplified version as well as a more detailed version specifically for veterinarians (Note: an OAHN login is required to access the more detailed version.  Veterinarians and veterinary technicians can sign up for free here.  OAHN membership also provides access to our quarterly network reports and the opportunity to contribute to surveillance efforts in companion animals through our quick, 5-minute quarterly online survey).

Label claims are the regulatory-approved claims of effectiveness that manufacturers are granted based on the evidence they submit. That doesn’t mean the product won’t work on other parasites or that all products with the same label claim work equally well, but products with label claims against a particular parasite have proven effectiveness.

The tables represent products and claims in Canada. While that’s pretty applicable internationally, some products may have different claims in different countries (not because their parasites are tougher or weaker, but mainly based on regulatory rules and what the company has asked for). As always, products and labels may change, and while we will attempt to keep up with those changes, the table should only be used as a guideline.  Owners should always consult their veterinarian and veterinarians should always check the label to ensure the product is right for the animal in question.

Melioidosis in a dog

Posted in Dogs

Melioidosis is a disease that wouldn’t come to mind with a sick dog here in Canada. However, it is present in various parts of the world and is also a serious disease in people. Recognizing a case in North America is rare (and it’s easy to miss since most veterinarians haven’t even heard of it, let alone seen a case before). Yet, with the amount of international dog movement, it’s something to be aware of.

A case report in Zoonoses and Public Health (Ryan et al 2018) outlines some of the issues, describing the public health response to a case identified in the US.

Here are the highlights:

  • The affected dog was imported from a shelter in Thailand (where the disease is common) to a private shelter in the US.
  • Shortly after arrival, the dog was taken to a veterinary clinic for evaluation due to his chronic inability to walk, which had been a problem for about 2 years.
  • On arrival, the dog was bright and alert, and pretty much looked like you’d expect for a dog that couldn’t walk and that had lived in a shelter for a couple years. The dog had lost a lot of muscle in his hindlimbs and had abnormal, infected skin from urine scalding (since the dog was also incontinent).
  • A urine culture was performed and Burkholderia pseudomallei, the cause of melioidosis, was identified (causing, I assume, much excitement in the lab since this is a bug that is supposed to be handled with higher levels of biosafety than your regular diagnostic lab).  See image above of a culture plate with B. pseudomallei (photo credit: Gavin Koh).
  • Because of the zoonotic risk, incurable incontinence and lack of a proven way to confidently eliminate the bacterium, the dog was euthanized.

Burkholderia pseudomallei is a bacterium that is normally found in soil and water, particularly in southeast Asian and northern Australia, but it can be found in many other countries. Since it can cause a range of illnesses in people, including life-threatening bloodstream infections and pneumonia, exposure to an infected dog that is shedding the bacterium in urine (+/- other body sites) raises concern.  However, it’s important to note that the vast majority of infections in people are thought to come from soil or water exposure, and there is limited evidence of direct animal-human transmission.

The field investigation looked at the shelter, veterinary clinic and lab. Twenty-seven people from the clinic and lab had been exposed to the dog, its urine or the bacterial isolate (excluding anyone who might have had contact with the dog in transit – those individuals are often forgotten and can be very difficult to tract). Sixteen of these people were considered a concern, with 14 classified as low risk, and 2 (both individuals with underlying medical conditions) classified as high risk. One of the high risk individuals was given prophylactic antibiotics. Six of the 16 agreed to symptomatic monitoring by public health personnel, and three agreed to blood tests.

  • Six people were identified as potentially exposed in the shelter, but only 3 had direct contact with the dog’s urine. Blood samples were collected from them to see if they had any evidence of exposure to the bacterium.
  • No one got sick.
  • One person had an increase in antibodies against the bacterium, suggesting  exposure, but the increase was minor and therefore inconclusive.

A few take-home messages:

  • Logical importation practices are needed. How much time and expense went into shipping a paralysed dog transcontinentally from one shelter to another, when it was ultimately euthanized in the end anyway? I realize everything is done with good intentions, but thank about what could have been done for local homeless animals with the time, effort and expenses that were incurred here.
  • Routine basic infection control practices need to be followed in shelters and clinics to protect against situations like this when something unexpected is encountered.
  • Moving an individual (human or animal) from one area to another can result in moving pathogens along with them. Understanding the risks from different regions is important, but is also a challenge.

As mentioned in my last post, we’ve started a disease mapping initiative to hopefully help fill some of the knowledge gaps when it comes to regional disease risks in imported dogs. Here’s our first melioidosis map; click here to go to the interactive map that will let you zoom in.  Please contact us if you have information relating to other areas where melioidosis is present so we can keep improving the map.

International animal disease mapping

Posted in Dogs

We’ve tried a number of different infectious diseases initiatives in the past, aimed at increasing infectious disease education and awareness of both veterinarians and pet owners. Some have worked very well (like this blog), others less so. However, there’s still a lot that can be done.

Here’s our latest initiative – whether it flies or flops remains to be seen, but I think it could be useful.

Most weeks (or multiple times a week), I get a call about infectious disease concerns in an imported dog. It’s not hard to identify some of the infectious disease risks (and it gets easier the more I do it); however, we don’t have a  centralized record of what diseases are coming from different regions.

So, why not try to make one?  It’s easier said than done.  Why is that?

  • There aren’t a lot of people working in the companion animal infectious disease world, so there are lots of gaps. “If you don’t look, you don’t find” is a good adage in this regard.
  • So, the available information is patchy, particularly for certain diseases, and some diseases may seem common in certain areas simply because someone happens to be looking for them there.
  • That means we can confidently say that a disease is present in a particular region, but it’s harder to confidently say that a disease is not present.

Yet, it’s still a good start.

So, here’s the first, basic attempt: a map of canine influenza.

The static map is above. Click here for a more interactive map that will provide details when you hover over a country and allow you to zoom in. The colour scale  ranges from my crude categories of “hyperendemic/very common” to “widespread” to “has been sporadically or previously identified” to “not reported/no data.” It’s an empirical scale but it suits our needs for now. The maps also have the ever-present issue of using a national scale which can distort regional risks (e.g. Canada is a very big country and something that’s present in one region may be of no concern in another). These maps are being done in R and I’m just learning how to map with that, so hopefully they’ll get a bit better over time.

Crowd-sourced surveillance will be useful with this project. While formal research is limited for many diseases in different regions, veterinarians and owners know what they see. We’ll be looking for input into the maps that we develop, especially data relating to developing regions and areas where research data are limited.

This is just the first attempt and more diseases will hopefully be coming soon.  As always, input is welcome.

Freeze dried vs fresh vs frozen raw pet foods

Posted in Cats, Dogs, Parasites, Salmonella, Toxoplasmosis

I think I’ve covered this before (probably a few times), but the question keeps coming up so it can’t hurt to talk about it again:

Is freeze-dried raw pet food any different than fresh or frozen raw diets, from a microbiological standpoint?

We don’t have much pet food-specific research, but there’s little reason to believe there would be much difference when it comes to the things we’re concerned about. When I want to preserve bacteria, I freeze them or freeze-dry them. Those are actually the preferred methods for long-term storage. Freezing or freeze-drying is a pretty hospitable process and state for most bacteria. Some, such as Campylobacter, don’t tolerate freezing (or especially fresh-thaw cycles) as well as others, so freezing or freeze-drying might have some impact on those specific bugs. For the higher profile pathogens like Salmonella and Listeria, it probably doesn’t make a difference.

The story is quite different for some parasites. Many parasites and parasite eggs don’t tolerate freezing (that’s why fish for sushi is typically frozen at some point). Some are hardier than others, though. Toxoplasma, a potentially important foodborne parasite, is susceptible to freezing, but only if the temperature is low enough and the time is long enough (e.g. -12C for 3 days will kill most Toxoplasma cysts).

So, the take home message is that for of the microbes that we’re worried about with raw meat,  freezing or freeze-drying is NOT a food safety practice. It’s food preservation, not bacterial control.

Companion animal parasite forecasts: US

Posted in Dogs

I’m a little late writing about this (since I’m talking about 2018 forecasts midway through 2018), but the Companion Animal Parasite Council (CAPC)‘s parasite forecasts are worth a look. They don’t include Canada, but they show some interesting predicted patterns in the US.

The maps are below, but check out the CAPC website to get more details.

Updated Lyme disease risk map and infographic

Posted in Dogs, Other diseases

Public Health Ontario has once again posted their updated Lyme Disease Risk Areas map for 2018.  For comparison, you can still also access the 2017 map too, and you can see that once again (not surprisingly) the risk areas have expanded somewhat, including more of Eastern Ontario, as well as a few notable spots in York region and around Kenora in Northern Ontario.

  • The estimated risk areas are calculated as a 20 km radius from the centre of a location where blacklegged ticks were found through active drag sampling.
  • While low (but getting higher), there is a probability of encountering blacklegged ticks almost anywhere in the province.
  • Within estimated risk areas, blacklegged ticks are mainly found in woody and/or brushy areas.

For more information about how these maps are generated and how areas are selected for active tick dragging, download the complete pdf document here, or check out the PHO Lyme Disease website.

The Ontario Animal Health Network (OAHN) has also incorporated the updated map into the infographic “Ticks and Lyme Disease in Ontario: What’s the real risk?”  The graphic can be a useful tool for talking to clients about putting the risk of Lyme disease in context.