Worms & Germs Blog

Update: Canine Influenza, Ontario (April 9)

Posted in Dogs

No news is good news… at least hopefully. The past week was quite encouraging.

No new cases of canine influenza were identified in Ontario. A couple of “inconclusive” results were obtained from dogs in the Northumberland cluster that were previously positive. I approach these as essentially “weak positives,” because it means the test detected viral nucleic acids in the dog’s sample but at a low enough level that it’s not considered definitive. It’s not unusual to see inconclusive results after positive results, as viral shedding gradually decreases. Most often these dogs are negative the next time, although we have seen some go from inconclusive back to positive.

We haven’t seen any new positives in Muskoka for a couple of weeks, and at this point the infected dogs that we have been following are all known (i.e. negative test results) or likely to be negative (i.e. dogs that were positive a while ago but where we don’t have a final negative sample). So, it’s possible that there is no more flu activity in that area.

The fact that there were no new positives in Northumberland is encouraging, but we still have some positive dogs to watch there.  We’ll continue to test in that area for a while to see if there is any other flu activity that we don’t yet know about.

Lone Star ticks and meat allergy: Is there a concern in dogs?

Posted in Dogs

Lone-Star-tick-associated meat allergy is an interesting phenomenon in people that is getting a lot of attention, especially as these ticks (like others) are expanding their range.  The condition itself is one of those odd-ball quirks of nature that you’d never expect.

The basic story goes like this:

  • galactose-alpha-1,3-galactose (alpha-gal) is a carbohydrate that’s part of cell membranes in most mammals, except humans, apes and Old World monkeys. It’s also found in the saliva of the Lone Star tick (Amblyomma americanum, pictured above)
  • Because it’s a “foreign” substance to humans, if their immune system encounters it, it may create antibodies against the carbohydrate. This can happen with a Lone Star tick bite, as the body reacts to tick saliva.  Although it’s rare, this can lead to allergic reactions when the body encounters alpha-gal again.
  • Since alpha-gal is present in red meat (but not poultry or seafood), ingestion of meat in people with a lot of antibodies against alpha-gal can result in an allergic reaction. This usually occurs 3-8 hours after eating and is often manifested as development of itching, hives, vomiting and diarrhea. Anaphylaxis is possible but uncommon.

Lone Star ticks can bite dogs and there’s been some talk about meat allergy as a reason for tick prevention in dogs. But, what’s the story?

  • We don’t really know, but I have a hard time seeing any risk of dogs developing meat allergy secondary to Lone Star tick bites.
  • Since dogs are mammals of the non-human/ape/monkey variety, the are already full of alpha-gal. It’s not a good survival technique for a host to create antibodies that attack itself, so a Lone Star tick bite that transferred alpha-gal would just be adding a minute amount to a dog that’s already full of the carbohydrate. There shouldn’t be any risk of antibody development or food allergy.

There are a lot of good reasons for tick prevention in dogs, but I can’t see acquired meat allergy being one of them.

Update: Canine influenza, USA (April 4)

Posted in Dogs

I’m slowly catching up so here are last week’s data from IDEXX Laboratories on the canine flu situation in the US. The two main areas of concern remain California and Nevada. The number of new cases dropped quite a bit from the previous week. That’s encouraging, but it can be hard to interpret passive surveillance data from diagnostic laboratory submissions. Do the reduced numbers mean there is less disease, or just that people are testing less (since they know flu is present in those regions and are therefore making presumptive diagnoses rather than confirming with testing). Let’s hope the decrease is actually an indication of reducing disease transmission, not owner/veterinarian testing fatigue.


Update: Canine influenza, Ontario (April 2)

Posted in Dogs

I’ve been slow to provide an update, partly because I’ve been sick (not with canine flu) and partly because there’s fortunately less to report.


  • We are still testing but it’s pretty low yield. One challenge is the baseline upper respiratory disease activity in the area. There are various viruses and bacteria that cause flu-like illness in dogs that are relatively common. The presence of a reasonable background of other upper respiratory pathogens complicates assessing the situation but I’m optimistic it is under control in that area.
  • We are getting repeated samples from positive dogs to see when they stop shedding. As of our last round of testing, all of the known positives had stopped shedding the virus.


  • The number of confirmed cases here has surpassed that in Muskoka. We are still getting new positives, which is a concern. However, only 5 new cases were identified last week, an improvement from the previous week.
  • A link has been established from the Niagara region to the Northumberland cluster. This involves a dog that was taken from a Niagara region animal shelter and transported to Northumberland. An outbreak occurred in the Niagara area shelter but it looks like the virus didn’t escape.

Other regions

  • We are still testing dogs in other areas, but no confirmed cases have been identified in other regions. One “inconclusive” result is being followed up.

Hopefully the next updates are even more boring.

Update: Canine influenza, Ontario (March 23)

Posted in Dogs


  • Things have been quiet there for a while and this seems to be a nice success story. The two flu clusters that were active in January were contained and nothing new has been seen.


  • Good progress has been made. Few new cases have been identified over the past two weeks.
  • One problematic aspect of H3N2 flu is the shedding period.  Some of the early cases in this cluster are still shedding the virus. This is a major issue because recovered dogs can look perfectly healthy but still be infectious. The duration of shedding that we’re seeing in some dogs poses a significant problem since they can be a source of infection for a long time, and it’s harder to convince people to maintain isolation when their dog looks normal.
  • We’re continuing to test and while I was a bit skeptical initially, this cluster might be controllable.


  • This area is still a concern because of the number and distribution of cases. However, there are some encouraging signs.
  • The number of new cases is decreasing. Further, the limited number of new cases that we’re seeing all have a clear link to a known case or facility. That’s good because cases of unknown origin would mean we have more unknown sources of infection out in the community. Unknown sources are a problem because we’re not able to intervene to help direct infection control measures.
  • This is the cluster that I thought might have signaled the end of any potential “search and contain” approach. However, I think we still have a chance to prevent further spread, so active surveillance is continuing.

The rest of Ontario:

  • We’re still watching.
  • It’s a challenge since there’s always some degree of “background noise” of infectious respiratory tract disease, and clusters of infections occur regularly, even when they’re not caused by flu. Some days it seems like I talk to every vet or owner of a dog in Ontario with a cough, but it’s good that there’s awareness.
  • How to conduct surveillance for a novel virus amongst a background of endemic respiratory disease is a challenge. Testing everyone that’s sick would be ideal, but isn’t possible given the available time and resources. Testing just dogs with known links to cases risks missing new clusters (as highlighted by the Muskoka and Northumberland clusters, that did not have obvious origins at the start).
  • We are continuing to test in other areas of the province, with a focus on clusters of infection, especially where there are high attack rates. For example, if 10/10 dogs in a group get sick, I’m much more concerned it’s flu than if only 2/10 get sick (even though flu would be possible in either case).
  • While we’re still trying to sort things out, testing will continue.

Animal-associated deaths: United States

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

Quick question: what species do you think accounts for the most human deaths in the US?

A recent paper in Wilderness & Environmental Medicine (Forrester et al, 2017. An update on fatalities due to venomous and nonvenomous animals in the United States, (2008-2015)) explored this topic, using a CDC database to study deaths that occurred between 2008 and 2015.

  • 1610 deaths were reported, or about 200 per year. That’s a reasonably big number, but when you consider size of the population in the US, it’s low. That rate corresponds to 4.8 deaths per million people per year.
  • Most deaths were caused by non-venomous animals, something that shouldn’t be surprising considering venomous species are much less commonly encountered in most parts of the US compared to non-venomous species.
  • However, the number of venomous animal-associated deaths was still quite high, mainly from stinging insects (probably from allergic reactions).
  • Dogs accounted for the most deaths, which also isn’t surprising given the large number of dogs in the US. Most pose little to no threat, but all it takes is a very small number of problematic dogs (and/or owners) for a noticable number of deaths to occur.
  • Males accounted for 72% of deaths from animal encounters. Females only led in deaths caused by centipedes and venomous millipedes. I can explain why males might dominate some of the categories, but the female link to centipedes and millipedes eludes me. Probably, it’s just a function of small sample size, since only 3 people died from those: 2 females and 1 male.
  • The highest mortality rate was in people over 65 years of age. Stinging insects accounted for much of that.
  • Deaths from dog attacks were nearly four-fold higher in kids 4 years of age or younger.

The study provides some interesting information, but the dataset is probably far from complete in terms of all deaths associated with animals. It includes deaths from “bite, contact, attack or envenomation.” That doesn’t seem to include infection, and zoonotic infections certainly would add to the totals.

For example, the table indicates no deaths from rats. That might not sound strange, but it depends on how deaths are considered. I wouldn’t expect rat attacks to be a cause of death, but I do know of rat bite fever deaths during that time frame. Deaths from infections that came from an animal are still deaths and are important to consider.

Similarly, only one non-crocodile/alligator reptile-associated death was reported. However, Salmonella has killed more than that. Various other zoonotic infections are probably also missed. They’re fortunately still rare, but they do occur.

Regardless, some simple practices and precautions can reduce the risk of deaths from animals, whether by trauma or infection. There’s no way to completely eliminate risk, but reducing mortality and morbidity rates is a worthy (and attainable) goal.

Image: Brown recluse spider, Loxosceles reclusa, is one of three spider species with medically significant venom in North America (CDC Public Health Image Library #1125)

Turtles and Salmonella

Posted in Other animals, Reptiles, Salmonella

Taking a break from canine flu and going back to an old favorite… Salmonella and reptiles.

CDC has released their final update on a multistate outbreak of Salmonella Agbeni infections associated with contact with pet turtles. Turtles are very well known as high risk animals for transmitting Salmonella. Even healthy turtles often carry Salmonella and people can be exposed through contact with turtles or their environment.

Here are the highlights of the final report:

  • 76 infections were identified in people from 19 states between March 1st and December 1st, 2017. Presumably, the true number of infections was many times that because most cases are never diagnosed.
  • Details were available for 63 people who were infected, 30 of whom were hospitalized. That’s a very high percentage for an outbreak like this.
  • 32% of infections were in kids under 5 years of age. That’s common, based on their increased susceptibility to disease, a greater likelihood samples will be collected for testing in sick kids, and close contact between kids and turtles.
  • 38% of sick people reported contact with turtles or their environments. The Salmonella strain that was involved had been previously found in turtles from a street vendor, supporting turtles as a source.

This report doesn’t change anything since we know that turtle contact is a big risk factor for salmonellosis, and that kids are the highest risk group. That’s why reptiles should not be kept in households with young kids (or other high risk people).

More information about pet turtles can be found on the Worms & Germs Resources – Pets page.

Image: Two red-eared slider turtles, Trachymys scripta elegans (CDC Public Health Image Library #15619)

Canine influenza disinfection

Posted in Dogs

I’m lazy so I’ll use the blog to answer a question that I’m getting a few times a day.  Today’s question: how to disinfect a veterinary clinic if there is a concern about canine influenza?

The good news is that influenza viruses are pretty wimpy. They’re enveloped viruses, meaning they are covered by a fragile fatty layer. This envelope is easy to disrupt, and doing so kills the virus. As a result, enveloped viruses don’t survive for long in the environment. In contrast, non-enveloped viruses can be very tough. Some survive for long periods of time in the environment and are resistant to certain disinfectants. Canine parvovirus, poliovirus and norovirus are some examples of hardy non-enveloped viruses.

But back to influenza.  Because it’s enveloped, pretty much any routine disinfectant will inactivate it. The virus will also disintegrate on its own, given a bit of time. Survival for a day or two is possible on surfaces like stainless steel and plastic. Duration of survival is shorter on surfaces like cloth or paper, usually less than 8-12 hours (Bean et al, J Infect Dis 1982).

While it’s nice that flu virus doesn’t survive for long, in a veterinary clinic (or any other higher risk environment like a kennel) we’d rather speed up the process to reduce the risk of transmission. That’s where cleaning and disinfection come in.

  • Cleaning is an important first step. Disinfection of grossly contaminated surfaces is difficult. Cleaning actually removes the majority of contaminants. So, skipping cleaning and going right to application of a disinfectant is not as effective and should be avoided.
  • Basically any disinfectant will kill influenza virus. However, since we shouldn’t have tunnel vision about only targetting flu, it’s a good idea to use as effective a disinfectant as possible. (My main recommendation is an accelerated hydrogen peroxide product.) That being said, any routine clinic or kennel disinfectant is fine for the purposes of flu and many other bacteria and viruses.
  • Disinfectants need to be used right. The proper concentration has to be used and the right contact time with the surface must be provided. These vary from product to product, so check the label. Contact time is often overlooked – a quick spray followed by an immediate wipe (as is common) may not do much beyond physical removal from wiping.  The disinfectant needs to have time to do its job.
  • Disinfectants only work where they have contact. Attention should be paid to fully covering potentially contaminated surfaces, as well as equipment such as stethoscopes, bowls and anything else that might touch a dog (particularly its mouth).

The approach to disinfection for influenza is pretty straightforward. The devil is in the details, though, as disinfection isn’t always done carefully or properly. It’s never a bad time to review disinfection practices to make sure they’re adequate, are understood by all personnel and are followed.

Canine influenza update: US and Canada, March 13

Posted in Dogs

United States (data courtesy of IDEXX Laboratories)

  • Canine flu continues to cause problems in the US, particularly the west coast.
  • Northern California (471 cases) and Nevada (207 cases) are the hotbeds. As ever, since these data are from diagnostic laboratory submissions, they probably represent the minority of cases (since most dogs with respiratory tract disease don’t typically get tested).
  • Range expansion continues in the affected US areas, as the virus spreads gradually into adjacent areas.
  • Expansion into some major urban centres such as San Francisco and Sacramento raises concern because of the dog density in those areas.

As for Ontario, I’ll give a more detailed update soon.

  • I did another road trip today for sampling and we’re still approaching this from a “search and contain” standpoint.
  • We have flu confirmation in three regions; however, no new affected regions have popped up recently (although we remain on the lookout).
  • The few new positives we’ve seen in the Muskoka region over the past few days have been expected cases (i.e. dogs that were known to have been exposed and which were being tested as part of our investigations). I can live with that, as long as we can continue to identify and isolate the infected and exposed cases. If we start seeing new unexpected cases turning up I’ll be more concerned.
  • The Northumberland cluster is the main concern now as it is less contained.
  • I’m getting a lot of questions about how long I’ll continue testing. My general response is “until it’s gone or it’s clear it’s not containable” (money’s another limitation, but that’s another story). Neither of those situations has clearly occurred yet, and I’d hate to look back in a year and think that we didn’t try. I’m not sure what our odds of success are, but we’re still trying to eradicate the virus from Canada.

More updates to follow.

Ontario canine flu update: March 10

Posted in Dogs

Active canine influenza cases are still known to be present in two regions in Ontario.


  • A small number of dogs from the initial cluster of cases in the Orillia/Bracebridge/Gravenhurst region are still shedding the virus, as expected given this virus can be shed by some dogs for a few weeks. The dogs that made up the earlier cases should be done shedding soon, hopefully decreasing the pool of infected (and infectious) dogs.
  • Surveillance is still underway to detect new clusters.
  • At this point, we have not seen rapid expansion since the problem was first identified and containment measures were implemented. We would like to continue to test dogs in this area that develop signs consistent with influenza (e.g. cough, runny eyes, runny nose). This is particularly true for dogs with known contact with confirmed influenza cases, but testing of any dogs with flu-like disease is desirable to detect new clusters and make sure we know the extent of the problem.

Northumberland County

  • Multiple cases are present in this area, all currently linked to one source.
  • How H3N2 influenza got to this region is still being explored, and while I have some ideas, we do not yet know for sure. It may be indirectly linked to the Muskoka cluster, but this has not yet been confirmed.
  • As in Muskoka, testing of contacts of dogs with influenza, as well as other dogs in the area with flu-like disease is underway.  Owners of local dogs that develop these signs should contact their vet to discuss testing, as we want to determine the extent of the problem and try to contain it.


  • No positives were identified in our round of testing Friday. No known active cases are present in the region at the moment.
  • It is strongly suspected that canine influenza was the cause of disease in a couple of clusters of dogs; however, sampling was late enough that we might have missed active shedding. While that complicates our investigation of the spread, it’s good news in that we don’t have known infectious dogs in the area.
  • Hopefully the small clusters of disease that were likely flu have been contained and this area is now flu-free. However, as with the other regions, we want to continue to do some testing in case there are still cases in the area.

Other areas of Ontario

  • We are testing a smaller number of dogs from other areas, with no known link to the affected regions. This is low yield because we don’t expect influenza to be present (but I didn’t expect it to be present in the Muskoka group either). This testing will be continued in the short term to try to make sure we do not have other clusters (associated or not).