Deer COVID investigated after possible human infection

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This article was published 04/03/2022 (1367 days ago), so information in it may no longer be current.

OTTAWA — A research team led by the National Microbiology Lab in Winnipeg is the first to have found evidence of a deer possibly infecting a human with COVID-19 last year.

“It’s not like this is happening all the time, but it gives us information that this (research) is something we need to continue,” said Bradley Pickering, head of special pathogens at the National Centre for Foreign Animal Diseases, located in the Arlington Street lab.

In a study published Feb. 22, which is still awaiting formal peer review, Pickering’s team observed the genetic sequences of 300 samples taken from white-tailed deer last November and December 2021, from southwestern and eastern Ontario.

Of those deer, 17 from rural areas near London, Ont., had the virus that causes COVID-19, five of which had “a new and highly divergent lineage” of the coronavirus, with 76 mutations from the original strain first identified in Wuhan, China.

Some of those mutations may have resulted from the virus adapting as it spread among the deer, parallel to the strains circulating among humans. The genetic backbone was similar to the Beta variant, which gained prominence in South Africa but was far overshadowed in Canada by Delta by the time the samples were collected.

Other mutations date back to a year before the samples were collected, and had been documented in transmission from humans to minks in Michigan.

“There (generally) hasn’t been a virus that’s gone into a population that has changed and evolved, that’s been there for a year and then it comes back,” Pickering said. “It could be a parallel evolution of the virus in deer, or there could be an intermediate host; we don’t know.”

His team also analyzed samples of roughly seven million PCR tests taken from nearby testing centres, and found one local man had a similar form of the virus, “after having known close contact with deer,” which Pickering said strongly suggests the deer gave the man COVID-19.

Pickering’s team specializes in studying zoonosis, which is when an infectious disease jumps from an animal to humans.

The novel coronavirus has been documented to have spread from humans to lions, tigers and deer.

Researchers are also finding evidence of so-called spillback events, when an animal infects a prior host species, such as human beings. Evidence of that spread has resulted in European mink farms culling millions of animals.

At the start of the pandemic, Pickering’s team looked into whether farmed animals such as pigs, chickens and turkeys would be susceptible to catching COVID-19 from humans.

They have started looking into wild animals, which Pickering notes are much harder to track and take samples from. The Winnipeg lab is developing rapid tests that could work on animals.

“SARS-CoV-2 is really good at infecting a lot of different things,” he said, referring to the formal name of the virus.

“You sort of have a chance of it continuing in any of these animals.”

But Pickering said he doesn’t want people to panic.

“Sometimes, the virus might go into wildlife and almost become more attenuated, because it’s adapting to wildlife as opposed to people. It could also go the other way; it’s this unknown.”

The virus could mutate as it spreads in animals, and present a vaccine-resistant strain that goes on to infect people. Pickering argues it’s best not to worry about those situations, and instead encourage research that could help the world cope with such a scenario if it emerges.

“The idea that there’s a possibility (of transmission to humans) and it’s actually circulating in animals is important, for us to continue to understand what’s going on, to be prepared and know what to expect.”

dylan.robertson@freepress.mb.ca