Parks Canada has closed off a Saskatchewan national park's remote prairie dog colony to the public after a rodent from the area tested positive for sylvatic plague — the same bacteria that causes the bubonic and pneumonic plagues in humans.
"In this case, the real risk for people is very low," Adriana Bacheschi, the acting superintendent for Park Canada's south Saskatchewan field unit, said Wednesday.
"The last time there was a case of a human infection in Canada was in 1939, and it was not fatal."
But the closing of the Broken Hills prairie dog colony, located inside Grasslands National Park southeast of Val Marie, Sask., is still being taken as a precaution.
Parks Canada is also taking steps to prevent an outbreak of the flea-carried disease among the province's already-threatened prairie dog population. Grasslands is the only place in Canada where prairie dogs still live in the wild.
"It could have very severe impact on prairie dog populations if we didn't control it right away," said Bacheschi.
According to the United States Geological Survey (USGS), 90 per cent of prairie dogs in a colony can die during an outbreak.
Parks Canada staff discovered the dead black-tailed prairie dog in early July, and sent it off for initial testing to the Western College of Veterinary Medicine at the University of Saskatchewan in Saskatoon.
The frozen rodent arrived at the college packed in Ziplock bags inside a cooler, says Trent Bollinger, a professor at the college's veterinary pathology department. As the regional director of the Canadian Wildlife Health Cooperative, Bollinger was tasked with doing the autopsy on the animal.
"This was all done under a biosafety hood because, back in 2010, we diagnosed… plague in another prairie dog from Grasslands," he said.
Bollinger's examination found physical signs of plague similar to those seen in 2010. A later analysis by the Public Health Agency of Canada's National Microbiology Laboratory in Winnipeg confirmed the latest plague diagnosis.
Two dead ground squirrels from the colony were also sent off for testing, and early results from the examination of one squirrel also suggest the plague, said Bollinger.
"The reaction usually to the word 'plague' is quite... people react strongly," said Bacheschi of Parks Canada. "Any plague, when you say 'plague', it creates a reaction of fear for people."
But she stressed things have changed since the bubonic plague's heyday during the Middle Ages.
"This is a very treatable disease with antibiotics," she explained. "It's not the public health risk it once was. It's really important for people to understand that."
The Broken Hills prairie dog colony is not close to the national park's campgrounds or most of its visitors facilities, and visitors would have to break from one of the park's trails and do "quite a bit of hiking" to reach the colony, according to Bacheschi.
But Broken Hills and two other nearby colonies—where no dead rodents have been found—will be kept closed "for a while" just in case, she said.
Most people become infected by the plague when bitten by infected fleas or when handling infected animals or their tissues, according to the USGS.
Which is why, to avoid any direct contact with the prairie dog, Bollinger performed his autopsy with the animal inside a sealed-off glass biosafety cabinet, with Bollinger's hands and arms covered in two sets of long gloves — one latex, one rubber.
"Everything is bleached and disinfected within the cabinet before it's moved out of the general [autopsy] suite," said Bollinger, adding that the animal's carcass is ultimately taken off-campus for incineration.
Parks Canada staff have begun dusting burrows in the Broken Hills colony with an insecticide to kill off fleas that may be carrying the disease.
Other prairie dog colonies within Grasslands National Park remain open, said Bacheschi.
But all colonies are closed off to campers' pets, as has been the case since the first infected prairie dog was discovered in the park in 2010.