An Unexpected New COVID Concern: Deer

Lots of deer appear to be infected, and they could provide a 'reservoir' for virus to mutate
By John Johnson,  Newser Staff
Posted Nov 11, 2021 12:19 PM CST
Updated Nov 14, 2021 12:55 PM CST
An Unexpected New COVID Concern: Deer
COVID appears to spread quickly within the the population of white-tailed deer.   (Getty/RT_images)

A new study is throwing a COVID curveball: It seems that a surprisingly high number of white-tailed deer have the infection. And while the deer don't seem to get sick, they could function as a "reservoir" in which the virus can lurk, mutate, and perhaps jump back to humans, reports NPR. The upshot of the discovery is that this could make it harder, if not impossible, to eradicate the virus altogether. The researchers tested nearly 300 wild deer (including road kill and those felled by hunters) in Iowa last year, and the results were "actually quite stunning to us," says co-author Vivek Kapur of Penn State.

In the first months of testing, about 30% of deer tested positive. And during the winter of 2020, the figure surged to 80%, meaning the prevalence of the virus in deer was up to 100 times greater than that of Iowa residents at the time. While the study was confined to Iowa, researchers say the results likely hold true of deer populations throughout the US, per the Guardian. The scientists say the deer probably picked up the virus through exposure to people, though how is unclear, reports the Duluth News Tribune. One possibility is by encountering human fluids, perhaps the urine of hunters or hikers. "Right now that's really the million dollar question—how are they getting exposed," says another co-author, Rachel Ruden of Iowa State.

What is clear, however, is that once the virus shows up in the deer population, it spreads quickly. Thus, the concern: "If the virus has opportunities to find an alternate host besides humans, which we would call a reservoir, that will create a safe haven where the virus can continue to circulate even if the entire human population becomes immune," says Suresh Kuchipudi at Penn State. This "reservoir" also raises the risk of the virus mutating. "Now the question is: Can the virus spill back from deer to humans?" asks virologist Linda Saif of Ohio State University. "Or can deer transmit the virus effectively to grazing livestock? We don't know the answers to those questions yet, but if they are true, they're obviously concerning." (More COVID-19 stories.)

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