White-tailed deer in Quebec are catching the COVID-19 virus, Environment and Climate Change Canada confirmed Wednesday.
This is the first time the virus has been detected in Canadian wildlife.
It was found in three white-tailed deer from the Estrie region of Quebec in a finding confirmed by the National Centre for Foreign Animal Disease.
The samples were collected between Nov. 6 and 8 through a big game registration station in southern Quebec. The deer showed no clinical signs of the disease and were all apparently healthy, said Environment and Climate Change Canada.
The most recent research shows COVID-19 remains primarily a disease spread from human to human and the risk of transmission from deer to humans in Canada is considered low.
But Environmental Canada spokesman Gabriel Brunet said the discovery emphasizes the importance of ongoing surveillance for SARS-CoV-2 in wildlife, since information on the impact and spread of the virus in wild deer populations is limited.
A study by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service found antibodies to the COVID virus in 33 per cent of white-tailed deer sampled in New York, Michigan, Pennsylvania and Illinois between January 2020 and March 2021. The study was conducted because white-tailed deer number about 30 million in the U.S. and the animals often come into close contact with people, the USDA said.
“Studying the susceptibility of certain mammals, such as deer, to the SARS-CoV-2 virus helps to identify species that may serve as reservoirs or hosts for the virus. It also helps us understand the origin of the virus and predicts its impacts on wildlife and the risks of cross-species transmission,” it said.
The USDA does not know how the deer were exposed to the virus, but says it could have been through humans, the environment, other deer or another animal species. However, there is no evidence the deer are playing a significant role in the spread of the virus to people.
A second study by Penn State University found more than 80 per cent of white-tailed deer sampled in different parts of Iowa between December 2020 and January 2021 tested positive for SARS-CoV-2.
The study found 33 per cent of all deer tested positive, suggesting the white-tailed deer may be a reservoir for the virus to continually circulate. The findings raised concerns that new strains of the virus could emerge that pose a threat to wildlife and possibly humans.
Canadian scientists were aware of the U.S. studies and are conducting their own through Environment and Climate Change Canada and the Canadian Wildlife Service, B.C.’s provincial wildlife veterinarian Caeley Thacker said in an interview last week.
Researchers are collecting samples to look for SARS-CoV-2 in deer and other wildlife species, said Thacker. While samples collected from B.C. deer in November haven’t been tested yet, “from what I know, they haven’t found any positives in previous samples from B.C. wildlife.”
The scientists are interested to see if deer or any wildlife species are carrying the virus and could become reservoirs for the disease, she said. “That would mean it would persist in a wild population and raise concerns that it could spread to human beings, depending on the virus strain, wildlife species and human interaction.”
Black-tailed deer are found on Vancouver Island and the coast. The rest of the province has white-tailed deer and the more prevalent mule deer. Experimental studies using captive deer found mule deer could be as susceptible to the virus as white-tailed deer.
“But we don’t know what that looks like in a wild context,” said Thacker. “And the virus hasn’t been detected in mule deer yet.”
It’s possible black-tailed deer could become infected, but what’s important is whether they develop any symptoms and whether they are able to transmit it, said the veterinarian.
“An animal can become infected, but they may not get sick and they may not be able to transmit it,” said Thacker. “Even if we find a positive in B.C., more research is going to be needed to know what the risk is for humans.”
Environment and Climate Change Canada is advising people to wear a well-fitting mask when exposed to respiratory tissues and fluids from deer, practise good hand hygiene and avoid spraying fluids from the tissues as much as possible. The Canadian Wildlife Health Cooperative has published wildlife health and SARS-CoV-2 handling guidelines on its website (cwhc-rcsf.ca/covid-19.php).
“Early on in this pandemic, we weren’t aware of what species could carry or transmit the virus. As we’re learning more, we’re putting more precautions in place because we know more,” said Thacker.
The virus has infected a number of species around the world, including farmed mink, cats, dogs, ferrets and zoo animals, including tigers, lions, gorillas, cougars and otters.
Last month, B.C. decided to phase out mink farming after data from the B.C. Centre for Disease Control identified the potential for the virus to mutate in mink, potentially reducing vaccine effectiveness, and be passed along to people.
In July 2021, mink at three mink farms and workers at two mink farms tested positive for the virus, raising concerns about transmission of the virus to humans and to wild animals.