Scientists have recently discovered what they are calling a silent epidemic of coronavirus among North America’s most ubiquitous species – the white-tailed deer.
This raises the possibility of new variants of SARS-CoV-2 emerging in these deer populations. If a new variant were to emerge, it could potentially pose a risk to humans.
There are an estimated 30 million white-tailed deer in the U.S. and since the start of the COVID-19 pandemic in the United States back in 2020, experts were aware that the coronavirus is a zoonotic disease. This means it first emerged in animals, although researchers are not sure precisely which species it originated, and it could spread back to animals.
Researchers have found evidence in experimental studies that ferrets, hamsters, cats, primates, bats, and mink can acquire SARS-CoV-2 infections. After first erupting in April 2020, the coronavirus spread among captive minks in Europe, and by June of 2021, scientists estimated, the virus had infected as many as seven million mink on more than 400 farms in Europe and North America, killing more than 700,000 of the animals
But of even more interest to scientists is the spread of the coronavirus among free-ranging deer, which display few signs of illness, are tricky to detect, and difficult to contain.
The research on white-tail deer, which appears in the Proceedings of the National Academy of Sciences of the United States of America, raises the possibility of new variants of SARS-CoV-2 emerging in these deer populations. If a new variant were to emerge, it could potentially pose a risk to humans.
This is a significant finding in the research because adaptation in animals is one route by which new variants are likely to emerge.
“This is a top concern right now for the United States,” said Dr. Casey Barton Behravesh, who directs the One Health Office — which focuses on connections between human, animal, and environmental health — at the Centers for Disease Control and Prevention.
“If deer were to become established as a North American wildlife reservoir, and we do think they’re at risk of that, there are real concerns for the health of other wildlife species, livestock, pets, and even people,” she added.
Researchers weren’t looking for COVID
Medical News Today spoke with Dr. Suresh V. Kuchipudi, Dorothy Foehr Huck, and J. Lloyd Huck, Chair in Emerging Infectious Diseases at Penn State University, Pennsylvania. Dr. Kuchipudi is the corresponding author of the present study.
Many of the white-tail deer first tested for the coronavirus were actually being tested for chronic wasting disease (CWD). But the researchers also took the samples and tested them to see if deer had gotten COVID, and when.
CWD is a fatal, neurological illness occurring in North American cervids (members of the deer family), including white-tailed deer, mule deer, elk, and moose. Since its discovery in 1967, CWD has spread to 23 states and two Canadian provinces. CWD is contagious; it can be transmitted freely within and among cervid populations. No treatments or vaccines are currently available.
Scientists have been tracking the spread of CWD through retropharyngeal lymph node samples of deer brought down by hunters or killed in road accidents.
“Earlier studies showed the susceptibility of white-tailed deer to experimental SARS-CoV-2 infection and antibody evidence of SARS-CoV-2 disease in wild deer in multiple states of the U.S. Therefore, we did this study in collaboration with the Department of Natural Resources in Iowa to detect SARS-CoV-2 RNA in deer tissues, confirming the SARS-CoV-2 infection of deer in natural settings.”
The study ended up collecting over 2,000 lymph node samples, of which 1,200 were positive. The researchers looked at the types of variants found in the samples and cross-referenced these with known outbreaks of the variants in humans.
According to this information, the researchers believe that multiple transmissions from humans to deer were occurring and that deer were then transmitting the virus to other deer.
Dr. Kuchipudi points out that this finding is a problem because the deer could function as a reservoir for the virus, giving it space to mutate.
“Continued circulation of an RNA virus, such as SARS-CoV-2, in humans or nonanimal hosts could lead to novel variant emergence. It is possible that such novel variants could be more transmissible and potentially cause more severe diseases in humans and animals,” said Dr. Kuchipudi.
“In addition, novel variants emerging from an animal reservoir could escape the protection afforded by the current human COVID-19 vaccines.”
