The United States Department of Agriculture (USDA) and Cornell University published research in May 2021 that demonstrated that in a laboratory setting, white-tailed deer are susceptible to SARS-CoV-2, can shed the virus in nasal secretions and infect other deer, and can develop SARS-CoV-2 antibodies following infection. All infected deer were subclinical, that is, they showed no observable signs of disease. The USDA then analyzed blood that had been collected over several years from wild white-tailed deer in Illinois, Michigan, New York, and Pennsylvania. While SARS-Cov-2 antibodies weren’t detected in any samples from the pre-pandemic period (i.e., prior to 2020), antibodies were detected in 40% of the total samples from 2021, which demonstrated that wild deer were exposed to the virus and mounted an immune response. More recently, the USDA has detected the SARS-CoV-2 virus in wild white-tailed deer in Ohio.
As a species, white-tailed deer are susceptible to SARS-CoV-2, they can carry and shed the virus, they can spread the virus to other deer, and they can mount an immune response following exposure (i.e., generate antibodies). In the wild, white-tailed deer have been exposed to the virus and can carry the virus. There is no evidence that exposure or active SARS-CoV-2 infection has a negative impact on the health of individual deer or wild deer populations.
We don’t know how wild deer were exposed but it is not surprising considering white-tailed deer’s proximity to human populations that are experiencing widespread SARS-CoV-2 infections. We also don’t know if wild deer in Pennsylvania are actively infected or shedding the virus. These are some of many unanswered questions that we hope to resolve through ongoing testing and research.
The risk remains low as there is currently no evidence that any animals, including wildlife, are playing a significant role in spreading SARS-CoV-2 to humans. COVID-19 is a disease of humans and is spread by infected people via respiratory droplets and aerosols. There is also no evidence that the virus can be transmitted through preparing and consuming food, including wild game meat.
We have tested bats held by Pennsylvania wildlife rehabilitators to ensure they are not infected with SARS-CoV-2 prior to being returned to the wild. Bat species are already in decline due to diseases like white-nose syndrome and some species of bats outside of North America have been shown to be susceptible to the virus. To date, there have been no SARS-CoV-2 detections in any Pennsylvania bats. We are also performing limited SARS-CoV-2 testing of wild deer during the 2021-2022 hunting season and of select road-killed deer to determine how widespread exposure has been in Pennsylvania deer, as well as if any deer are actively infected or shedding the virus. Elk are suspected to be susceptible to the virus as well, so limited SARS-CoV-2 testing of elk is also being pursued. Additional research will determine any possible implications.
Leaving wildlife wild and avoiding contact is the best way to protect yourself and wildlife. While there is no evidence that deer can spread SARS-CoV-2 to humans, wildlife may carry other diseases that can spread to humans and domestic animals. For wildlife biologists, rehabilitators, hunters, and others who cannot avoid contacting wildlife, it is important to practice good hygiene by wearing disposable gloves, and when appropriate, masks or other personal protective equipment. Don’t touch your face, eat, drink, or smoke while handling any wildlife. Always use soap and water to wash your hands and any equipment, tools, or surfaces that contacted wildlife. Equipment, tools, or surfaces can then be disinfected with a 10% bleach solution for a minimum 10-minute contact time before rinsing with clean water and allowing to air dry. Always ensure that wild game meat is cooked to the proper internal temperature.