HQ Team
July 30, 2024: The SARS-CoV-2 virus was detected in six backyard species in the southeastern US state of Virginia with unique viral mutations with lineages closely matching variants circulating in humans, according to a study.
The highest exposure of the virus, that causes Covid-19, was found in animals near hiking trails and high-traffic public areas, suggesting the virus passed from humans to wildlife, according to scientists at the Fralin Biomedical Research Institute at VTC, the Department of Biological Sciences in Virginia Tech’s College of Science, and the Fralin Life Sciences Institute.
The virus was detected in six common backyard species, and antibodies indicating prior exposure to the virus were found in five species, with exposure rates ranging from 40% to 60%, depending on the species.
The investigators tested animals from 23 common Virginia species for both active infections and antibodies indicating previous infections. They found signs of the virus in deer mice, Virginia opossums, raccoons, groundhogs, Eastern cottontail rabbits, and Eastern red bats.
The virus isolated from one opossum showed viral mutations that were previously unreported and can potentially impact how the virus affects humans and their immune response.
May 2022-September 2023
The research team collected 798 nasal and oral swabs across Virginia from animals either live-trapped in the field and released, or being treated by wildlife rehabilitation centers. The study was conducted between May 2022 and September 2023.
The team also obtained 126 blood samples from six species. The locations were chosen to compare the presence of the virus in animals in sites with varying levels of human activity, from urban areas to remote wilderness.
The study identified two mice at the same site on the same day with the same variant, indicating they either both got it from the same human, or one infected the other.
Genetic tracking in wild animals confirmed both the presence of SARS-CoV-2 and the existence of unique viral mutations with lineages closely matching variants circulating in humans at the time of research, further supporting human-to-animal transmission, the study found.
The findings highlight the identification of new mutations in SARS-CoV-2 in wildlife and the need for broad surveillance, researchers said. These mutations could be more harmful and transmissible, creating challenges for vaccine development.
No animal-to-human transmission
The scientists said that they found no evidence of the virus being transmitted from animals to humans, and people should not fear typical interactions with wildlife.
“The virus can jump from humans to wildlife when we are in contact with them, like a hitchhiker switching rides to a new, more suitable host,” said Carla Finkielstein, professor of biological sciences at the Fralin Biomedical Research Institute at VTC.
“The goal of the virus is to spread to survive. The virus aims to infect more humans, but vaccinations protect many humans. So, the virus turns to animals, adapting and mutating to thrive in the new hosts.”
SARS-CoV-2 infections were previously identified in wildlife, primarily in white-tailed deer and feral mink. The data suggested exposure to the virus had been widespread in wildlife and that areas with high human activity could serve as points of contact for cross-species transmission.
“This study was motivated by seeing a large, important gap in our knowledge about SARS-CoV-2 transmission in a broader wildlife community,” said Joseph Hoyt, assistant professor of Biological Sciences at Virginia Tech’s College of Science.
White-tailed deer
“A lot of studies to date have focused on white-tailed deer, while what is happening in much of our common backyard wildlife remains unknown.
“This study highlights the potentially large host range SARS-CoV-2 can have in nature and really how widespread it might be. There is a lot of work to be done to understand which species of wildlife, if any, will be important in the long-term maintenance of SARS-CoV-2 in humans,” he said.
Researchers are not certain about the means of transmission from humans to animals. One possibility is wastewater, but Virginia Tech scientists believe trash receptacles and discarded food are more likely sources.
While the study focused on the state of Virginia, many of the species that tested positive are common wildlife found throughout North America. They are likely being exposed in other areas as well, and surveillance across a broader region is urgently needed, Assistant Professor Hoyt said.
“There is a lot of work to be done to understand which species of wildlife, if any, will be important in the long-term maintenance of SARS-CoV-2 in humans.”
