Researchers at Penn State University revealed that whitetail deer are highly susceptible to COVID-19 infection and probably already spreading it. The researchers sampled more than 300 deer in Iowa between December 2020 and January 2021 and found the virus that causes COVID-19 in 80% of the samples. Another study in Ohio, between January and March 2021, found similar results.
Of course, when it comes to whitetail deer, Texas is No. 1 — by far in terms of population. In 2019, Texas Parks and Wildlife estimated that more than five million deer range across the state. The impact on Texas is unclear, and there's no current monitoring for the virus among the whitetail population.
The Edwards Plateau ecological area, which includes Kerr County and most of the Hill Country, has one of the highest densities of whitetail deer in the state — with an estimated two million animals.
The virus has infected dogs, cats, lions, tigers and gorillas, but all of that has a documented connection with humans. The development with deer is not quite as simple.
"This is the first direct evidence of SARS-CoV-2 virus in any free-living species, and our findings have important implications for the ecology and long-term persistence of the virus," said Suresh Kuchipudi, Huck Chair in Emerging Infectious Diseases, clinical professor of veterinary and biomedical sciences, and associate director of the Animal Diagnostic Laboratory, Penn State. "These include spillover to other free-living or captive animals and potential spillback to human hosts. Of course, this highlights that many urgent steps are needed to monitor the spread of the virus in deer and prevent spillback to humans."
A familiar sight across Kerrville and Kerr County — deer in the front yard. |
Earlier this year, the U.S. Department of Agriculture found the virus that causes COVID-19 in 40% of deer — and that was released in August. The Penn State study was offered on a pre-publication site before it will be peer-reviewed.
University of Minnesota's. Dr. Michael Osterholm, one of the nation's leading researchers on Chronic Wasting Disease in deer, discussed the finding in his podcast last week.
"This really raises a litany of questions," said Osterholm, the Center for Infectious Disease and Policy executive director at the University of Minnesota. "When you dig into these studies, you can see some pretty interesting, and frankly some puzzling, even frightening results."
The frightening part, according to Osterholm and others, is that many of the deer were free-ranging — meaning they weren't coming into contact with humans. There were deer herds that lived in urban areas that did test positive — possibly exposed to the virus by humans. What is concerning is the reverse — deer spreading it to humans.
"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," said Vivek Kapur, a professor of microbiology and infectious diseases at Penn State. "This also raises the possibility of the spillback from deer back to humans, especially in exurban areas with high deer densities."
Osterholm pointed out that the studies did not examine the clinical impact on deer — meaning how the virus affected the animals.
"A major issue for me is that we don't know how they these deer are being exposed," Osterholm said in the podcast. "A number of theories have been posed, ranging from human-assisted feeding to sewage discharge sites. The study out of Ohio did find a higher prevalence of infection of deer located in urban areas, which makes sense because these settings would provide more opportunities for interaction to occur, but no clear links have been made."
The studies also coincided with hunting season in both states where the samples were taken, leading researchers to caution hunters.
"While no evidence exists that SARS-CoV-2 can be transmitted from deer to humans, he believes 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 Kapur.
The scientists genetically sequenced the samples, finding at least 12 different COVID-19 strains in the animals.
"The viral lineages we identified correspond to the same lineages circulating in humans at that time," said Kapur. "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. This also raises the possibility of the spillback from deer back to humans, especially in exurban areas with high deer densities."
REFERENCE LINKS
Penn State study: https://www.psu.edu/news/research/story/deer-may-be-reservoir-sars-cov-2-study-finds/
Story by National Public Radio: https://www.npr.org/sections/goatsandsoda/2021/11/10/1054224204/how-sars-cov-2-in-american-deer-could-alter-the-course-of-the-global-pandemic
Podcast with Dr. Michael Osterholm of CIDRAP, University of Minnesota: https://www.cidrap.umn.edu/covid-19/podcasts-webinars/episode-77
USDA study: https://www.aphis.usda.gov/publications/animal_health/qa-covid-white-tailed-deer-study.pdf
