How SARS-CoV-2 in American Deer Could Change the Course of the Global Pandemic

Scientists have evidence that SARS-CoV-2 spreads explosively in white-tailed deer and that the virus is widespread in this deer population across the United States.

The researchers say the findings are quite concerning and could have broad implications for the long-term course of the coronavirus pandemic.

Since SARS-CoV-2, the coronavirus that causes COVID-19 disease, first appeared, there have been several signs that white-tailed deer are very susceptible to the virus – and that many of these animals are ‘were catching across the country.

In September of last year, computer models SARS-CoV-2 suggested could easily bind and enter the cells of the deer. A recent survey of white-tailed deer in the Northeast and Midwest find that 40% of them had antibodies against SARS-CoV-2.

Now, vets at Pennsylvania State University have found active SARS-CoV-2 infections in at least 30% of deer tested in Iowa in 2020. Their study, published online last week suggests that white-tailed deer could become what’s called a reservoir for SARS-CoV-2. That is, animals could carry the virus indefinitely and periodically transmit it to humans.

If so, it would essentially destroy any hope of eliminating or eradicating the virus in the United States – and therefore the world – according to the veterinary virologist. Suresh Kuchipudi at Penn State, who co-led the study.

“If the virus has the ability to find an alternative host besides humans, which we would call a reservoir, it will create a safe haven where the virus can continue to circulate even if the entire human population becomes immune,” he says. “And so it is becoming more and more complicated to manage or even eradicate the virus. “

In the study, Kuchipudi and his colleagues looked for the presence of the SARS-CoV-2 virus in the lymph nodes of nearly 300 white-tailed deer, including more than 100 wild deer. “So these deer were either deer dead on the road or deer living in the wild that the hunters had killed. [to eat], explains the veterinary microbiologist Vivek Kapur at Penn State, who also co-led the study.

What they found left Kapur and Kuchipudi stunned. “It was actually quite amazing for us,” says Kapur. “We were very surprised to see such a high number of positive samples.”

From April to December of last year, about 30% of the deer they tested were positive for SARS-CoV-2 by a PCR test. And then during the winter wave in Iowa, from November 23, 2020 to January 10 of this year, about 80% of the deer they tested were infected. At the height of the outbreak, Kapur says, the prevalence of the virus in deer was actually about 50 to 100 times the prevalence among Iowa residents at the time.

During this time, the team also sequenced the genes of nearly 100 samples of the virus. They found that the variants circulating in deer corresponded to the variants circulating in humans.

These genomic sequences suggest that during the pandemic, deer caught the virus several times in Iowa, Kapur says. “The data is again very consistent with frequent spillover events from humans to deer and then transmission between animals. “

Virologist Linda saif at Ohio State University’s College of Veterinary Medicine, humans likely infect white-tailed deer across the country. The white-tailed deer are native to North America, Central America, and northern South America. In the United States alone, there are approximately 30 million animals.

“We also detected the virus in deer in Ohio,” she says. “And there are antibody studies that suggest the prevalence of COVID infections in deer is quite high in the Midwest and East. “

Although the virus does not appear to make the animals sick, Saif says, the new data from Iowa is “very concerning.”

“Now the question is: can the virus spread from deer to humans? Or can deer effectively transmit the virus to grazing livestock? We don’t yet know the answers to these questions, but if they are true they are obviously of concern, ”she said.

Another concern, Saif says, is that SARS-CoV-2 could evolve inside deer and create new strains of the virus. Researchers have already documented such a scenario with mink on farms in the Netherlands and Poland, she points out.

In these studies, farm workers transmitted the virus to animals in captivity. As the virus spread through the mink, it mutated and created new variants. These new versions of the virus then spread to humans, researchers reported.

Ultimately, tracking the emergence of new variants can become much more complicated, says Kuchipudi.

“If we are to continue to be proactive on emerging variants – and not be surprised by one that suddenly appears – there is an urgent need to continue monitoring SARS-CoV-2 in wildlife,” he says, “in especially in animals that could serve as a reservoir, such as deer.

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