With COVID-19 now detected in Ontario deer, wildlife experts seek to fill research gap

A Guelph expert says crucial research is underway after the discovery of five white-tailed deer in southwestern Ontario that tested positive for COVID-19.

The Ontario Ministry of Northern Development, Mine, Natural Resources and Forestry confirmed these are the first cases reported in free-ranging wildlife in Ontario.

Cases in wildlife have been detected in deer in Quebec and Saskatchewan, as well as northeastern U.S.

Scott Weese, chief of infection control at the Ontario Veterinary College at the University of Guelph, said it's still not known how the deer contracted COVID-19 and more research is needed to determine the possibility of transmission from deer to other species.

"This is a human driven pandemic and we spill it over into animals probably not uncommonly, but we don't really know how it got into deer," Weese told CBC K-W.

"The other potential is the animal bridge: cats are quite susceptible to this virus. If you have a person that has a cat and the cat goes outside, could the cat be a bridge?" he added.

He said if deer can transmit the virus to other animals or among themselves, then it can be challenging to control the spread and could potentially create a reservoir of the virus.

He said the bigger concern is that transmission could lead to high replication and mutation rates that could cause issues if they spread back into people.

"If were starting to find old strains in deer or different strains [of COVID-19] in deer, then we'd be more concerned that this virus is hanging out for a while and changing," he said.

"If we're finding the same stuff we're finding in people then it would support the fact that this is just [a case of:] 'humans infect deer and it burns out'. But we need more time to sort that out."

The ministry said the samples were collected in November from the London area. To date, 213 samples were collected in 2021 and have been tested, with testing initiatives ongoing.

Based on current information, the risk of wildlife — including deer — spreading the virus to people is low. There has been no known transmission of COVID-19 from deer to humans at this time, the ministry said.

More research needs to be done to better understand the range of species that are susceptible and how species may be infected, carry and transmit the virus.

There is currently limited information on animals and COVID-19 and whether they can spread the virus. Usually it's spread from human to animal, or exposure from the environment.