Early in the COVID-19 pandemic, scientists worried cows and pigs might be potential victims or carriers of the coronavirus.
Research by the U.S. Department of Agriculture quickly found the virus didn’t threaten that livestock.
But when scientists began looking at one of the most common large wild species in the Midwest — white-tailed deer — they found the animals could catch and spread the virus.
“We really didn’t expect that,” said Mitchell Palmer, a veterinary medical officer with the USDA’s National Animal Disease Center in Ames.
The persistence of the virus among such a large wildlife population worries scientists. If the virus stays alive in deer, it might mean it could mutate into new variants that could prolong or worsen the coronavirus pandemic among people.
Since mid-2020, the researchers have been experimentally infecting captive white-tailed deer with different coronavirus variants at the Ames laboratory.
They’ve found the virus in deer nasal passages, but the deer don’t get sick. They don’t develop a fever or clinical signs of COVID-19, but they were infectious to other deer for five or six days. The virus and antibodies were detectable in the deer for at least three weeks.
The team, which includes USDA veterinary medical officers Mitchell Palmer, Paola Boggiatto, Alexandra Buckley and Eric Cassmann, as well as collaborators from Cornell University, got $1.7 million in funding through the American Rescue Plan to expand on studies of COVID-19 and white-tailed deer.
“We’re looking at virus dynamics in those animals over time,” Buckley said. “How long can you find virus in the nasal passages and how long do those antibodies last over time?”
The goal, Boggiatto said, is to further their understanding of what the virus is doing in deer.
“The research that we’re doing is just trying to help us understand what is going on in these animals, to help us understand the virus,” Boggiatto said, “and then hopefully be able to prevent disease transmission.”
When the team completes the research with captive white-tailed deer, they’re hoping it helps the USDA’s Animal and Plant Health Inspection Service better understand the results they’re seeing with deer in the wild.
The big concern, the researchers say, is the potential for white-tailed deer to serve as a reservoir for disease, meaning the deer are unaffected by infection and they can sustain it within their population. Palmer said there are 30 million white-tailed deer in the U.S. and once a disease is established in wildlife, it’s difficult to get out.
“It’s very possible that in this wildlife species that’s very numerous and it’s everywhere, that a new variant could pop out that might be infectious to people,” Palmer said.
The funding the team got from the American Rescue Plan Act of 2021 allows them to do up to three years of this research. They also got American Rescue Plan funding to study the coronavirus in elk populations.
