Deer in several states have tested positive for COVID, according to multiple studies. It is unclear where the deer caught the virus, but there is no evidence that humans can become infected by deer.
The U.S. Department of Agriculture's Animal & Plant Health Inspection Service collected 481 samples from deer in Illinois, Michigan, New York, and Pennsylvania between January 2020 and March 2021. They found SARS-CoV-2 antibodies in 33% of those samples.
The service said it's possible deer were exposed through people, the environment, other deer, or another animal species.
Similarly, a study by Pennsylvania State University found more than 80% percent of the white-tailed deer sampled in different parts of Iowa between December 2020 and January 2021 tested positive for SARS-CoV-2.
This was the first direct evidence of COVID in any free-living species, said Suresh Kuchipudi, clinical professor of veterinary and biomedical sciences and associate director of the Animal Diagnostic Laboratory at Penn State.
The findings have implications for the ecology and long-term persistence of COVID, said Kuchipudi, chair in emerging infectious diseases at the university. "These include spillover to other free-living or captive animals and potential spillback to human hosts," Kuchipudi said. "Of course, this highlights that many urgent steps are needed to monitor the spread of the virus in deer and prevent spillback to humans."
COVID is known to be carried by many mammals and several zoo animals like tigers and lions at the Bronx Zoo have gotten sick from the virus. According to the service, clinical signs of illness were not observed in the deer that were surveyed.
Following the federal study, wildlife officials in Oklahoma analyzed deer blood samples and found some did test positive for COVID.
The Oklahoma Wildlife Department said there is no known risk of COVID-exposure associated with cleaning deer or eating cooked venison. However, since deer hunting is prevalent in the state, the department has tips for handling the animal.
To reduce the risk of COVID infection when handling harvested deer, people should follow the same guidelines recommended to reduce human-to-human transmission, such as hand washing, gloves, and masks. Personal vaccination can also greatly reduce the risk of catching the virus, the department says.
The Massachusetts Division of Fisheries & Wildlife has similar advice for hunters in that state. Hunters should always "avoid handling or consuming wild animals that appear sick or those found dead," "wear gloves and a face shield when handling" game, and minimize contact with the brain or spinal tissue.
"Out of an abundance of caution for COVID-19, additional preventative measures include avoiding the head, lungs and digestive tract," the division says.
Other best practices include processing game outdoors or in a well-ventilated location, handling knives carefully to prevent accidental cuts and thoroughly washing hands and sanitizing all tools. Game meat should be cooked thoroughly to an internal temperature of 165°F to kill pathogens, the divisIon says.