‘Oddball’ parasite discovered in Yukon wolverines

Published: January 21, 2020

Wolverine Photo by Shutterstock/Galina Savina

When Rajnish Sharma, a University of Saskatchewan student, was studying parasites in the carcasses of Yukon wolverines out of a United States Department of Agriculture (USDA) laboratory he came across a bizarre genetic sequence. He was using the laboratory’s polymerase chain reaction machine—used to amplify DNA sequences—to examine a specific species of Trichinella, a common roundworm parasite found worldwide.

The DNA sequence Sharma was looking at “had no relationship or very little relationship to the existing known species of Trichinella,” explains Emily Jenkins, a veterinary microbiology professor at the University of Saskatchewan and Sharma’s supervisor.

The DNA sequence was a completely new species of Trichinella, becoming the 13th known species of Trichinella and subsequently named T13. What made the discovery so bizarre—enough to nickname the new species “oddball”—was that T13 presented itself during a routine test. “This is something that nobody knew about for the 20 years they’ve been using this test,” Jenkins says.

As it turns out, the T13 DNA fragments tested in the PCR machine were the same size as T. nativa, another species of Trichinella. Consequently, T. nativa would mask T13 during tests, obscuring it from view. “It was literally hiding in plain sight,” Jenkins says.

Similar to other species of Trichinella, T13 is a muscle-dwelling worm. It’s transmitted between carnivores who eat heavily infected muscle. In Canada, Trichinella is generally found in bears and walrus, but can also be transmitted to humans if they eat infected or undercooked meat. “The first sign that you have it is very vague gastrointestinal problems, like diarrhea,” Jenkins says.

The parasite becomes a serious concern once it makes its way into a muscle. There it can cause aches and inflammation. It’s not as serious if it happens to burrow its way into the muscles of your limbs, “but if it’s the muscles of your face or the muscles of your heart then it can become quite a bit more serious.” Trichinella has been known to cause heart and neurological problems.

Canadians are typically safe from Trichinella, considering most of the population doesn’t eat bear or walrus meat. But where it could be a threat is in pigs, Jenkins says because pigs eat meat. A recent insurgence of wild boar in Saskatchewan has Jenkins worried that Trichinella could spill over into Canada’s domestic pig population. “[Wild boar] are a problem because they can easily host Trichinella,” she says.

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While it is yet to be proven whether humans are susceptible to T13, they are vulnerable to other species of Trichinella, and an infected pig population would be an easy gateway to human infections.

Currently, T13 has been found in northern Canada’s Yukon wolverine population. Considering how recently the species was discovered, however, the team heading the T13 study has had little time to investigate other forms of wildlife or humans.

“So far, we’ve done limited testing on foxes and wolves and did not find T13, so it’s possible it could be a parasite of just wolverines, but Trichinella tends to not be too picky about what it will go in,” Jenkins says. Moving forward, the team plans on studying wolverines in Alaska and Russia to see how far T13 has spread.

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