UNIVERSITY PARK (TNS) — More than 80% of the whitetail deer in research conducted in Iowa from last December to January tested positive for the virus that can lead to COVID-19.
Although the nearly 300 samples were collected several states away — it was part of Iowa’s chronic wasting disease surveillance — researchers at Penn State believe the results should be an alert for deer hunters in Pennsylvania and everywhere.
While no evidence exists that COVID-19 can be transmitted from deer to human, “hunters and those living in close proximity to deer may want to take precautions, including during contact with or handling the animals, by wearing appropriate personal protective equipment and getting vaccinated against COVID-19,” said Vivek Kapur, a professor of microbiology and infectious diseases.
Overall, 33% of the samples statewide in Iowa tested positive, and the Pennsylvania portion of the same study found 31% of the 199 Keystone State deer tested positive for the antibodies.
Suresh Kuchipudi, clinical professor of veterinary and biomedical sciences and associate director of the Animal Diagnostic Laboratory at Penn State, said the findings suggest that deer may be a reservoir for the virus to continually circulate and raise concerns of emergence of new strains that may prove a threat to wildlife and, possibly, to humans.
“This is the first direct evidence of SARS-CoV-2 virus (which causes COVID-19) in any free-living species, and our findings have important implications for the ecology and long-term persistence of the virus,” Kuchipudi said. “These include spillover to other free-living or captive animals and potential spillback to human hosts.
“This highlights that many urgent steps are needed to monitor the spread of the virus in deer and prevent spillback to humans.”
Previous research by the U.S. Department of Agriculture showed that 40% of deer had antibodies against the coronavirus, but those antibodies only indicated indirect exposure to SARS-CoV-2 or an immunologically related organism and did not prove infection with SARS-CoV-2 or the ability to transmit the virus onwards.
}In the new study, the Penn State team examined nearly 300 samples collected from deer across the state of Iowa during the peak of human COVID-19 infection in 2020. The samples were extracted from deer retropharyngeal lymph nodes, which are in the head and neck.
“We found that 80% of the sampled deer in December were positive for SARS-CoV-2, which proportionally represents about a 50-fold greater burden of positivity than what was reported at the peak of infection in humans at the time,” Kuchipudi said. “The number of SARS-CoV-2 positive deer increased over the period from April to December 2020, with the greatest increases coinciding with the peak of deer hunting season last year.”
Kapur noted that the team also sequenced the complete genomes of all the positive samples from the deer and identified viral lineages corresponding to the same lineages circulating in humans at that time.
“The fact that we found several different SARS-CoV-2 lineages circulating within geographically confined herds across the state suggests the occurrence of multiple independent spillover events from humans to deer, followed by local deer-to-deer transmission,” he said. “This also raises the possibility of the spillback from deer back to humans, especially in exurban areas with high deer densities.
The research highlights the “critical need,” Kapur added, “to urgently implement surveillance programs to monitor SARS-CoV-2 spread within the deer and other susceptible wildlife species and put into place methods to mitigate potential spillback.”
