Researchers find virus that causes COVID-19 in Sask. deer

Researchers have found proof that SARS-CoV-2 is circulating among wild white-tailed deer in the province.

Deer in Ohio and other Canadian provinces have tested positive for the virus that causes COVID-19, but these are the first detections among Saskatchewan deer.

"It's not too surprising," said Emily Jenkins, a professor in the department of Veterinary Microbiology at the University of Saskatchewan's Western College of Veterinary Medicine.

"But it is somewhat concerning because it does suggest that there is spillover from humans into wildlife. And the big concern there is that the wildlife are able to self-perpetuate it."

The team investigating wildlife consists of members from the University of Saskatchewan, Environment and Climate Change Canada, the Saskatchewan Ministry of Environment and the Canadian Wildlife Health Cooperative.

The National Centre for Foreign Animal Disease confirmed the results after the team found positive results in viral RNA swabs of four deer harvested by hunters last year, according to a release from the University of Saskatchewan.

Environment and Climate Change Canada said in December last year they found the virus in one free-ranging white-tailed deer outside of Saskatoon.

Some tested deer also had SARS-CoV-2 antibodies

Of the 227 white-tailed deer tested in Saskatchewan, these four animals make up two per cent, the university says.

In addition, researchers looked at the blood of 62 deer to check for SARS-CoV-2 antibodies, explained Jenkins.

Ten per cent of those dead animals had antibodies, indicating previous exposure or active infection.

"We don't think that the virus survives for long in wastewater, particularly in treated wastewater," said Jenkins.

"However, if you look around, white-tailed deer are no strangers to our communities and even come right into our cities. So of all the wildlife populations that we thought might be susceptible to SARS-CoV-2, it wasn't a great surprise that deer were the ones that ended up testing positive."

These wild animals usually hang out in herds, meaning they can easily spread the virus among themselves, said Jenkins.

She believes COVID-19 does not have severe effects on infected deer.

"For the most part, the deer largely seem to be asymptomatic," she said. "That is a concern because that makes them a really good reservoir [for the virus]."

The findings in Saskatchewan come almost two years after researchers combined resources to build the wildlife surveillance program.

Since the beginning of the pandemic, the team considered which wild animals would be susceptible, explained Jenkins.

"Fundamentally, this really all comes back to our hunters and trappers who submitted the samples and allowed us to start this surveillance program," said Jenkins.

The team partners with Saskatchewan's chronic wasting disease surveillance program, which gives them access to submitted deer heads.

Animals with COVID-19

Other animals around the world have been reported to potentially get the virus from humans or other animals through natural exposure, according to the Government of Canada's website.

As of Feb. 28, the government's list includes minks and white-tailed deer as animals who can spread the virus to both humans as well as other animals, while other animals listed spread only between themselves.

In the early pandemic, some people were concerned about spreading the virus to their dogs and cats.

"Dogs, in particular, became a dead end as far as we're concerned, for spreading the virus," said Jenkins. "We know that there's very little evidence that cats are giving anything back to their owners."

Hunters should be cautious but not too concerned about harvesting deer in Saskatchewan, said Jenkins, as COVID-19 doesn't appear to be a foodborne disease.

"Even if a deer happened to be infected at the time of harvest, there isn't that level of close contact for aerosol transmission when you're processing the deer," said Jenkins.

The Government of Canada advises hunters and trappers to wash their hands regularly, wear gloves, goggles and a well-fitted mask when there is a possibility of being exposed to respiratory tissues and fluids, and cook the meat to an internal temperature of 74°C (165°F).

Possible deer-human transmission

With the first confirmed positive results in Saskatchewan white-tailed deer, researchers like Jenkins are concerned the virus might spill from animals into human populations after going through rounds of mutation and multiplication in deer.

That could already be happening in the country, according to preliminary research by a team of Canadian scientists.

Their research paper — posted on Feb. 25 on bioRxiv, an online archive and distribution service for unpublished preprints — still needs to be peer reviewed.

The group analyzed samples taken from deer killed by hunters in 2021 in southwestern Ontario to find out if deer may be able to transmit the virus to humans.

The scientists discovered a highly divergent lineage of SARS-CoV-2 indeer, while around the same time a genetically similar version was found in a person from the same area. 

That person was apparently in contact with deer.

"This particular case, while raising a red flag, doesn't seem to be hugely alarming," said Finlay Maguire, assistant professor at the department of Community Health and Epidemiology at the Dalhousie Unbiversity in Halifax. 

"While we haven't seen [deer-to-human transmission] happen directly, we sampled from the human case around the same time we sampled from the deer."