I collected and analyzed fox feces to assess parasite prevalence and distribution in foxes across Northern Canada. Besides the Nunavut fecal samples, I also analyzed other samples that were sent from foxes in the Yukon and Newfoundland by government veterinarians Drs. Jane Harms and Hugh Whitney.
Determining which parasites are present in fox populations is useful information for residents of nearby northern communities — particularly those who trap foxes — as many parasites can be zoonotic (transmitted between animals and humans). Interactions between foxes and domestic dogs can also increase the risk of transmission among humans, wildlife and domestic animals.
Parasites might have an impact on fox populations — especially if the population has never been exposed to those parasites before. Changes in the composition of the parasites in the area may be spurred on by various environmental factors such as climate change and host movements such as the northward expansion of red fox into Arctic fox territory.
Foxes are hosts to Echinococcus multilocularis, a tiny zoonotic tapeworm. Eggs in fox feces can infect rodent prey, and dogs that eat these intermediate hosts can become infected. People can also become infected through accidental ingestion of Echinococcus eggs that can develop into cysts that are potentially fatal.
The eggs of Echinococcus are very difficult to distinguish from the eggs of Taenia, another tapeworm, so researchers are exploring molecular methods. Part of my work included the molecular characterization of taeniid eggs that were recovered from feces of red and Arctic fox as well as from the feces of other wild canids. This work helps us to better determine the host and geographic distribution of this parasite.
WCVM graduate student Stacey Elmore was also part of the crew at Karrak Lake. For her PhD program, she's looking for the parasite Toxoplasma at different levels of the food web including geese as a migratory prey species, lemmings and voles as a resident prey species, and foxes as predators.
"As top level predators, people would have the same place as foxes in the parasite life cycle. Since humans hunt geese, we're looking at what the foxes have as an indication of whether humans could be at risk," explains Elmore.
"At the moment, no one knows what the primary transmission strategy of Toxoplasma is in the Arctic, but exposure to country food is an important risk factor for people."
Over the last two years, Elmore has also collected fox feces at Karrak Lake to determine what internal parasites are present in the population and monitor if there are any changes over time. Figuring out which parasites are present in an area isn't glamorous work, but it is a necessary starting point.
"Until we know what's there, we can't start asking other questions," says Elmore. "It's a lot of exploratory work, but the Arctic is a good place to study parasites because there's a lot of opportunity for transmission through carnivore species."
And while foxes may be the cutest animals on the tundra, they are also a great choice for studying parasites in the area.
"By studying the parasites in carnivore feces, we can get clues into what the animals are eating. By performing DNA sequencing on the parasites in the fox feces, we can sometimes tell if the parasites are of bird origin or caribou origin. This confirms previous studies looking at fox diets by other methods," says Elmore.
While fox parasites have been studied in some parts of the world such as Scandinavia, there hasn't been a lot of work done in Northern Canada. It's definitely been an interesting experience searching for parasites in populations of foxes spanning such a huge distance — from the very east to the very west parts of the country. I'm lucky to have worked in one of Canada's most beautiful and remote field sites.
Field research was funded by NSERC Northern Research Supplement, Northern Scientific Training Program, Environment Canada and Polar Continental Shelf Project. The Governments of Yukon and Newfoundland also provided funding for collecting and shipping samples.
Kailee Price of Surrey, B.C., is a third-year veterinary student who participated in the WCVM's Undergraduate Summer Research and Leadership program in 2013.