Deer in Iowa appear to be catching COVID-19 from humans. Could it happen in other states?
The coronavirus appears to have infected many of Iowa’s deer, posing risks the virus could mutate in the animals and then re-enter the human population in an altered version, a new study says.
“Our results suggest that deer have the potential to emerge as a major reservoir host” for the coronavirus, the study says.
The paper, which has not yet been published in a peer-reviewed journal, has been posted online. The findings were verified on Tuesday by federal scientists at the National Veterinary Services Laboratories, according to a spokesperson who spoke to the New York Times.
The findings were a surprise to the researchers, including veterinary microbiologists Suresh Kuchipudi and Vivek Kapur who led the Penn State study.
The new study focuses on deer in Iowa, but says, "there is no reason to believe that the same thing isn't happening in other states where deer are present."
Rachel Ruden, Iowa's state wildlife veterinarian, helped write the report. She told the Times it's not clear how deer picked up the coronavirus from humans and then spread it among themselves.
"All of this is a striking example that we’re all in this pandemic together," she said.
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Iowa Department of Natural Resources spokesperson Tammie Krausman said Tuesday her agency is not recommending specific precautions in light of the study's findings.
"DNR recommends that hunters keep hunting, and with standard precautions typically used when processing venison, like wearing gloves and thoroughly cooking the meat, the risk of exposure can be minimized," she wrote in an email to the Des Moines Register. "To date, there have been no cases of contracting COVID-19 from eating food, including hunted wild meat."
Researchers at Penn State University, the Iowa Department of Natural Resources and Iowa State University all participated in the study.
The researchers tested lymph-node samples from 283 deer that were killed by hunters, hit by cars or harvested at game farms from April 2020 into January 2021. Of those, 33% had been infected with the coronavirus. The infections appeared to become more widespread as the pandemic worsened among humans last year. Among 97 samples taken from deer between Nov. 23, 2020, and Jan. 10, 83% contained the coronavirus, the study says.
So far, there is no evidence that deer can infect humans with the coronavirus. However, the authors of the study worry about the persistence of the virus in Iowa's wildlife and the potential for a species to act as an "animal reservoir." Reservoirs happen when the virus mutates among a new host — like deer — until it reinfects humans with new variants, causing illness.
The study notes that such transmissions to other species are known to happen.
“Most viruses causing disease in humans originated in animals and many are capable of transmitting among multiple species,” the study says.
The best-known instance with the coronavirus has been in mink, millions of which were destroyed at European farms in 2020 because of concerns that sickened mink could infect humans. Some dogs and cats also have caught the virus from humans, and zoos have begun vaccinating their animals against it.
Another common example of "animal reservoirs" involves influenza viruses. Flu viruses are known to infect animals, including pigs and chickens, in which they mutate and then can spread into the human population.
The authors of the new study called for an "urgent need for a robust and proactive" approach toward a better understanding of how COVID-19 evolves within wildlife and "the implementation of enhanced surveillance programs" to identify potential animal reservoirs.
The study notes the United States has an estimated 25 million white-tailed deer, and they are the most popular animal for hunting.
Follow Andrea Sahouri on Twitter @andreamsahouri.