Coronavirus found in Iowa deer thought to be from humans

Iowa deer are getting the coronavirus — likely from humans — and they are passing it to other deer, a new study shows.

Although deer don’t seem to get COVID-19 symptoms, scientists worry the animals could serve as reservoirs for the virus to hang around and possibly be transmitted back to humans.

“Particularly if these animals are asymptomatic, then it allows the virus to persist a bit more easily in them than it does in us,” said Tyler Harms, wildlife biometrician and deer program leader for the Iowa Department of Natural Resources.

In a study not yet published, but released to the public Nov. 2, researchers at Penn State University and at the Iowa DNR, among other institutions, tested the lymph nodes of 283 Iowa deer harvested during the hunting season or killed by cars between April 2020 and December 2020. Of those deer, about a third had SARS-CoV-2 — the coronavirus.

Of 97 samples from Nov. 23, 2020, through Jan. 10 — which includes weeks were COVID-19 cases, hospitalizations and deaths among Iowa’s human population were surging — 80 percent showed the virus, the study notes.

About 40 percent of deer tested in Illinois, Michigan, New York and Pennsylvania had antibodies for COVID-19, indicating they’d been exposed to the virus, according to a report published this month in the Proceedings of the National Academy of Sciences.

Because the lineages of the virus in deer matched what was showing up in humans at the same time, scientists believe the deer likely got the virus from humans and then some deer transmitted it to others, Harms said.

“It’s likely they are getting it from humans, but the mode of transmission is really unknown,” he said.

Although humans usually pass the virus through aerosolized water droplets from their mouths or noses, that type of contact isn’t typical between humans and deer.

Some people have theorized the virus could have passed through surfaces, such as bird feeders that humans fill and then from which deer eat, Harms said, but surface transmission hasn’t been shown among humans.

The big question is whether deer can pass the virus back to humans, which so far hasn’t seemed to be happening.

The U.S. Department of Agriculture’s Agricultural Research Service last month reported eggs and live poultry, cattle, swine and insects like mosquitoes and ticks were not able to replicate the coronavirus that causes COVID-19.

The service included white-tailed deer in its study because deer are farmed in some places and because the genetic sequence of the SARS-CoV-2 virus cell receptors in deer closely align with those of humans, the report states.

“Deer did not get sick, but they quickly spread the virus to other deer,” the report notes.

As shotgun deer hunting season starts Dec. 4 in Iowa, the state DNR is suggesting hunters and meat processors wear gloves and wash their hands and equipment after processing deer carcasses.

“Those recommendations are not all that different from regular recommendations,” Harms said. But they “should minimize any risk of contracting COVID-19 from an infected deer.”

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