SARS-CoV-2, the virus that causes COVID-19, has been found to be widespread among wildlife species, according to new research conducted by Virginia Tech. The study revealed that the virus was identified in six common backyard animals, with antibodies indicating prior infection found in five species, showing exposure rates between 40% and 60%, depending on the species.
SARS-CoV-2, which is the virus behind COVID-19, is prevalent in wildlife populations, as indicated by research from Virginia Tech published on July 29, 2024, in Nature Communications. The virus was discovered in six common backyard species, and antibodies showing past exposure were present in five species, with exposure rates ranging from 40 to 60 percent based on the specific species involved.
Genetic analysis in wildlife confirmed not only the presence of SARS-CoV-2 but also unique viral mutations resembling variants that were circulating among humans at the time, supporting the idea that the virus can be transmitted from humans to animals, as stated in the study.
The highest rates of infection were found in animals living near hiking trails and busy public areas, implying that the virus may have passed from humans to wildlife, according to scientists from the Fralin Biomedical Research Institute at VTC, Virginia Tech’s College of Science, and the Fralin Life Sciences Institute.
These results emphasize the emergence of new mutations in SARS-CoV-2 among wildlife and the necessity for extensive monitoring, according to researchers. Such mutations may pose greater risks and enhance transmission, which complicates vaccine development.
However, the researchers emphasized that no evidence was found suggesting the virus is transmitted from animals to humans, and that routine interactions with wildlife should not be a cause for concern.
Researchers tested animals from 23 common Virginia species for active infections and antibodies from previous infections. They detected the virus in deer mice, Virginia opossums, raccoons, groundhogs, Eastern cottontail rabbits, and Eastern red bats. Notably, the virus isolated from one opossum exhibited previously unreported mutations, which could potentially influence how the virus interacts with humans and affects their immune response.
“The virus can transfer from humans to wildlife when we come into contact with them, much like a hitchhiker finding a new, more suitable host,” stated Carla Finkielstein, a biological sciences professor at the Fralin Biomedical Research Institute at VTC and one of the paper’s corresponding authors. “The virus’s goal is to spread and survive. It aims to infect more humans, but due to widespread vaccinations, it looks to animals as new hosts, adapting and mutating to thrive there.”
Before this study, SARS-CoV-2 infections in wildlife had mainly been recorded in white-tailed deer and feral mink. The Virginia Tech research significantly broadens the range of species examined and enhances understanding of virus transmission among wildlife. The data suggests that exposure to the virus in wildlife is widespread, especially in areas with high human activity that may facilitate cross-species transmission.
“This study was driven by the realization of a significant knowledge gap regarding SARS-CoV-2 transmission within the larger wildlife community,” noted Joseph Hoyt, an assistant professor of Biological Sciences at Virginia Tech and co-author of the paper. “Many previous studies have concentrated on white-tailed deer, while the status of our common backyard wildlife has remained largely unclear.”
The research team collected 798 nasal and oral swabs in Virginia from animals either captured and released or receiving treatment at wildlife rehabilitation centers. They also gathered 126 blood samples from six species, selecting locations to compare virus presence in animals across a spectrum of human activity, from urban to remote wilderness areas.
Additionally, the study uncovered two mice at the same location on the same day carrying the identical variant, suggesting they either contracted it from a common human source or one infected the other.
Researchers are uncertain about how transmission from humans to animals occurs. While wastewater could be a factor, the scientists at Virginia Tech lean towards discarded food and trash receptacles as more likely sources.
“The main takeaway is that this virus is quite widespread,” remarked Amanda Goldberg, a past postdoctoral associate in Hoyt’s lab and the study’s lead author. “We found positive results among many typical backyard animals.”
Although this study focused on Virginia, many of the tested species are common across North America, making it likely that they are exposed in other regions as well, highlighting the urgent need for broader surveillance, said Hoyt.
“The virus is indifferent to whether its host walks on two legs or four. Its primary objective is survival. Mutations that fail to provide a survival or replication advantage will not last and will eventually fade away,” explained Finkielstein, who also leads the Virginia Tech Molecular Diagnostics Lab established in April 2020 to boost COVID-19 testing.
“We recognized the critical need to sequence the genome of the virus affecting these species,” Finkielstein shared. “This was an enormous task that required a skilled team of molecular biologists, bioinformaticians, and modelers working in a top-notch facility. I’m proud of my team and our collaborators for their professionalism and contributions to our success.”
Continuous monitoring for these mutations is essential, say the scientists, as is further research into how the virus transmits from humans to wildlife, how it spreads within species, and potentially between different species.
“This study underscores the potentially vast range of hosts SARS-CoV-2 can occupy in nature and its extensive prevalence,” remarked Hoyt. “There is still a lot of research needed to determine which wildlife species, if any, may play a significant role in the long-term persistence of SARS-CoV-2 in humans.”
“What we’ve discovered,” added Finkielstein, “is that SARS-CoV-2 is not exclusively a human issue, and addressing its impact on different species and ecosystems requires a collaborative, multidisciplinary approach.”
