White-tailed deer test positive for COVID-19 in the U.S.

White-tailed Deer Photo by Shutterstock/Lester Graham

Masks may soon be required around more than just other people.

A study published in the Proceedings of the National Academy of Sciences (PNAS) found that COVID-19 antibodies appeared in 40 per cent of the 152 blood samples taken from white-tailed deer in Illinois, Michigan, New York, and Pennsylvania in 2021.

A second study tested 151 wild deer and 132 captive deer in Iowa between April and December 2020. Of the 283 deer samples, 94 tested positive.

Canadian experts are watching the findings closely. In an email from the Ministry of Natural Resources and Forestry (MNRF), the government confirmed that no deer or other wildlife in Ontario have tested positive for COVID-19. But officials are still advising people to be cautious.

Both studies suggest that the deer populations contracted the virus through human interactions, with the virus then transmitting among the animals. This theory, however, has no concrete evidence beyond the abundance of deer in urban centres and their social behaviour among one another.

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“There is some opportunity for human-to-wildlife transmission because there are some susceptible mammal species,” the MNRF said. “This type of transmission is a concern because the establishment of a reservoir in a wildlife population could lead to reverse zoonoses (i.e. wildlife-to-human transmission).”

After reservoirs are established in multiple wildlife populations, researchers in the PNAS study argued that it becomes almost impossible to eradicate COVID-19. Once the virus is in a new host, it can adapt and evolve into different strains, ones that the researchers said could be transmissible to humans and effective against our vaccines.

But before jumping to any drastic conclusions, Keith Munro, a wildlife biologist for the Ontario Federation of Anglers and Hunters (OFAH), said that further studies need to be completed.

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“The studies are really valuable for highlighting the ability for this virus to get into white-tailed deer,” he said, “but we definitely need more research to figure out how it spreads, what are the factors that cause it to move into deer, and how widespread it is in different environments.”

Munro also pointed out that neither study looked at contraction of the virus among deer based on age or sex. And without more information on the circumstances and environment in which the virus was contracted, you can’t extrapolate these results to Ontario’s deer population, he said.

The MNRF in cooperation with the Canadian Wildlife Health Cooperative and the Public Health Agency of Canada are currently testing wildlife for COVID-19, including deer.

Human-to-human transmission is still the most common conduit for COVID-19 spread, but the MNRF said that humans who have a suspected or confirmed case of COVID-19 should avoid close contact with animals, including pets, to protect them from the virus.

Vice versa, the chances of contracting COVID-19 from wildlife is low. Even preparing and eating hunted, wild game has shown no evidence of COVID-19 transmission. But to be cautious, the MNRF has advised a few simple actions to reduce risk:

  • Avoid contact with live, wild mammals. Feeding wildlife is discouraged because it can spread disease.
  • Follow normal health and safety steps when working with dead animals, such as wearing a mask and gloves—especially if you’re field-dressing wildlife.
  • Don’t work with animals if you have a suspected or confirmed case of COVID-19.
  • Get vaccinated.

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