Tularemia, also known as rabbit fever, is a plague-like illness that was first documented in Tulare, California in 1911. We know little about tularemia in Canada except that it appears to be rare in this country. The first known Canadian case was recorded in Timmins, Ontario in 1930, and the disease is considered to be endemic in Central and Western Canada, less so in the east.

The disease is caused by a bacterium (Francisella tularensis) that has been found in a small percentage of a broad range of mammals including beavers, ground squirrels, hares, muskrats, rabbits, voles and water rats, as well as other rodents. Though rarely encountered in Canada's wildlife, a tularemia outbreak affecting muskrats at Long Point, Ontario in 2020 caused quite a stir when at least 35 of the large rodents fell ill or died from the disease. In recent years, it's been determined that a small percentage of Arctic foxes in northern Canada (NWT, Nunavut) can be added to the list of mammals susceptible to tularemia. While dogs and cats appear to be largely resistant to developing symptoms from an infection, humans aren't so lucky.

People can contract tularemia in a surprising number of ways. Handling infected animals is a common way to do it, but drinking water, eating food or coming in contact with soil infected with the bacterium are all great ways as well. Inhaling contaminated dust or aerosols can also transfer the bacterium to humans and being bitten by an infected tick or deer fly is also right up there.

In the United States, it's believed that tick bites account for 50 percent of human infections. The percentage of Canadians who pick up tularemia from tick bites is less clear but between 2005 and 2006, 31 cases of tularemia were recorded in this country, most of which were contracted within the range of Rocky Mountain wood ticks in Western and Central Canada, suggesting that although there are multiple ways to contract the bacteria, infected tick bites may be the most common.

Now for some statistics: According to the Public Health Agency of Canada (PHAC), nine cases of tularemia were reported in Canada in 2013 and 10 in 2014. Four of those 2013 cases and two in 2014 were recorded in Manitoba. Manitoba also recorded two cases in 2015. In Ontario, there were six confirmed cases between 2005 and 2018 while in BC, 16 cases were recorded between 1991 and 2007.

Symptoms of tularemia usually start to manifest within several days following infection and are highly dependent on the source of that infection. I won't go into the full range here except to say that if someone contracts tularemia from a tick bite, they tend to experience flu-like symptoms and can develop a nasty ulcer near the site of the bite that lasts for several months. They can also experience swelling in nearby lymph glands, especially those located in the armpit or groin. Symptoms can range from mild to severe and, if left untreated, the fever associated with tularemia can last for up to six weeks. Happily, the introduction of modern antibiotics post-World War II means tularemia is now treatable.

Rabbit ticks (Haemaphysalis leporispalustris) and Rocky Mountain wood ticks (Dermacentor andersoni) across southern BC are known to carry tularemia. The disease can also be spread by American dog ticks (Dermacentor variabilis), which are permanent residents of Canada east of Alberta, and lone star ticks, which are not yet known to have become established in this country, but are increasingly frequent visitors here and their colonization of this country is thought to be immanent.

Photo of muskrat by Daniil Komov on Unsplash