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Study: Deer populations pose COVID risk to humans

July 12, 2023 – An estimated 3 in 10 white-tailed deer within the U.S. have been infected with COVID-19, and latest research suggests deer populations could also be a source of virus mutations transmissible to humans.

According to the U.S. Department of Agriculture, which led the research project, the virus was transmitted from humans to deer at the very least 100 times. The virus subsequently spread widely amongst wild deer populations, and there have been three possible cases of deer transmitting the virus to humans.

The data comes from tests conducted between November 2021 and April 2022 on greater than 12,000 deer spread across half of the United States. Sequencing of the virus present in the deer showed that the deer were exposed to all major variants, including Alpha, Gamma, Delta and Omicron.

Some of the findings on the transmission were published within the journal on Monday Nature communicationwherein researchers found that the virus was present in wild and domestic animals along with deer, including mink, rats, otters, ferrets, hamsters, gorillas, cats, dogs, lions and tigers. Animal-to-human transmission has been documented or suspected in mink and domestic cats, in addition to in white-tailed deer.

The findings are vital because animal populations could develop into “reservoirs in which the virus can circulate covertly, remain in the population, and be transmitted to other animals or humans, potentially causing disease outbreaks,” said the study, which was conducted in collaboration with scientists on the U.S. Department of Agriculture, the CDC, and the University of Missouri.

In the three cases of possible deer-to-human transmission, researchers said mutated versions of the virus previously found only in deer were present in COVID test samples from one person in North Carolina and two people in Massachusetts. These deer-specific mutated versions of the virus weren't present in some other human samples, indicating that the mutations arose in deer.

“Deer regularly interact with humans and are often found in human environments – near our homes, pets, sewage and garbage,” said researcher and University of Missouri professor Xiu-Feng “Henry” Wan, PhD, in a opinion“The potential for SARS-CoV-2 or any other zoonosis to persist and evolve in wildlife populations may pose unique public health risks.”

In the Nature communication In their article, the researchers suggested that deer could also be exposed to the virus through human food scraps, masks, or other waste products. The authors concluded that further studies are needed to find out how virus transmission occurs between deer and humans.