By Stephen Beech via SWNS
The virus that causes COVID-19 is “widespread” among wildlife, reveals new research.
Six out of 23 common species – including rabbits and bats – showed signs of SARS-CoV-2 infections during an examination of animals in the United States.
Antibodies indicating previous exposure to the virus were also found in five species – with rates of exposure ranging from 40% to 60%, depending on the species.
Genetic tracking of wild animals in Virginia 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.
The findings, published in the journal Nature Communications, are further evidence of human-to-animal Covid transmission, say scientists.
The study showed that the highest exposure to SARS-CoV-2 was found in animals near hiking trails and high-traffic public areas, suggesting the virus passed from humans to wildlife.
The research team from Virginia Tech says their findings highlight the identification of novel mutations in SARS-CoV-2 in wildlife and the need for broad surveillance.
They warned that the mutations could be more harmful and transmissible, creating further challenges for vaccine development.
But the team stressed, that they found no evidence of the virus being transmitted from animals to humans, and people should not fear any interactions with wildlife.
The researchers tested animals from 23 common species for both active infections and antibodies indicating previous infections.
They found signs of the virus in Eastern cottontail rabbits, deer mice, Virginia opossums, raccoons, groundhogs and Eastern red bats.
The virus isolated from one opossum showed viral mutations that were previously unreported – and could potentially impact how the virus affects humans and their immune response.
Professor Carla Finkielstein said: “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.
“The goal of the virus is to spread in order 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.”
Covid infections were previously identified in wildlife, primarily in white-tailed deer and feral mink.
The Virginia Tech study significantly expands the number of species examined and the understanding of virus transmission to and among wildlife.
The data suggests exposure to the virus has been “widespread” in wildlife and that areas with high human activity may serve as points of contact for cross-species transmission.
Professor Joseph Hoyt, of Virginia Tech’s College of Science, said: “This study was really motivated by seeing a large, important gap in our knowledge about SARS-CoV-2 transmission in a broader wildlife community.
“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.”
Researchers 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. They 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 also identified two mice at the same site on the same day with the exact same variant, indicating they either both got it from the same human, or one infected the other.
Researchers are not certain about the means of transmission from humans to animals.
They say one possibility is wastewater, but the team believes rubbish bins and discarded food are more likely sources.
Study first author Dr. Amanda Goldberg said: “I think the big take-home message is the virus is pretty ubiquitous.
“We found positives in a large suite of common backyard animals.”
The researchers say that while the study focused on Virginia, many of the species that tested positive are also common elsewhere, so it is likely they are being exposed in other areas as well.
Professor Finkielstein said: “The virus is indifferent to whether its host walks on two legs or four. Its primary objective is survival.
“Mutations that do not confer a survival or replication advantage to the virus will not persist and will eventually disappear.”
The team say further research is needed to establish how the virus is transmitted from humans to wildlife, how it might spread within a species, and perhaps from one species to another.
Hoyt said: “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.”
Finkielstein added: “What we’ve already learned is that SARS CoV-2 is not only a human problem, and it takes a multidisciplinary team to address its impact on various species and ecosystems effectively.”
