Are Deer Catching COVID From Hunters?

rainhard2 / Pixabay

I have serious doubts, but that’s what the authors of a new study from Penn State’s Animal Diagnostic Laboratory are suggesting. The researchers say that in a sample of 300 wild deer tested in Iowa, about 80% tested positive for SARS-CoV-2 viral RNA, which indicates infection within the animals. The question is, how did they catch it in the wild?

“The most plausible explanation is that it could be from humans,” said Suresh Kuchipudi, a clinical professor of veterinary and biomedical sciences and director of the Animal Diagnostic Laboratory, which provides wildlife disease surveillance and diagnosis for Pennsylvania government and wildlife management authorities.

The research was conducted by a team led by Dr. Kuchipudi and Vivek Kapur, a professor of microbiology and infectious diseases at Penn State, and in conjunction with the Iowa Department of Natural Resources. The study was advanced in the pre-print server bioRxiv, published by Cold Spring Harbor Laboratory, and submitted for peer review.

The study found that as many as 80% of wild white-tailed deer sampled in Iowa tested positive for SARS-CoV-2 viral RNA, direct evidence of infection with the virus. The number of infected deer increased from April to December 2020, with the greatest increases coinciding with the peak of Iowa’s deer hunting seasons from October through December. It was inferred that infections among deer were highest during periods of greatest human-deer contact, which occurred when some 11,000 Iowa hunters were in the field.

Now, I’ve never claimed to be the sharpest point on an antler, so I have to say I’m a little confused by this hypothesis. Haven’t we been told that the risk of human-to-human transmission while outside is slim-to-none, even when we’re standing closer than six feet to one another? If that’s the case, then how on earth are hunters passing on the coronavirus to deer while they’re up in a tree stand or in a hunting blind? Then there’s the fact that the vast majority of a time that a hunter is within six feet of a deer, the encounter is going to end with the deer heading off to the freezer and not returning to the herd.

One possibility? Deer are much more susceptible to COVID-19 than humans are.

In the Penn State study, researchers examined nearly 300 samples collected from deer across Iowa during the peak of human COVID-19 infection in 2020. They tested for SARS-CoV-2 viral RNA, and sequenced the complete genomes of all the positive samples from deer, identifying 12 SARS-CoV-2 lineages in the deer. The infection rate among sampled deer in 2020 was 50 times greater than infections reported among humans during the same time period. There is no evidence the coronavirus can infect other wild animals.

“The focus has always been that the virus is a human problem,” said Dr. Kuchipudi. “Now it is not just a human problem, it could be a wildlife health problem, too.”

Two things: first, there’s no evidence that the coronavirus can infect other wild animals? Really? Not even, say, bats? Who knew?

Even leaving that comment aside, which I’ll blame on reportorial ignorance or error, this doesn’t make much sense to me. Why would COVID be so much more prevalent in deer than humans, particularly if human hunters were the ones spreading the virus? And if deer are really that much more susceptible to catching COVID, how confident can researchers really be that they’re becoming infected from humans and not other wildlife?

Here’s another question. Do we know how seriously deer are affected by COVID? Kuchipudi says that her research demonstrates that COVID could be a wildlife health problem, but of the more than 200 deer that they found with evidence of an infection, were there any signs of serious illness? Have any deer carcasses been dissected to examine the lungs for evidence of scarring or decreased function? I’m not aware of any mass die-offs of deer being reported anywhere around the country since the start of the COVID pandemic, so it seems to me to be a bit premature to say this could become a huge problem for wildlife… or that it’s hunters who are causing so many deer to come down with the coronavirus.