A startling discovery reveals that 40% of wild deer in the United States are infected with a coronavirus

A new coronavirus appears to have somehow passed from humans to wild deer in parts of the United States.

In the Northeast, a recent federal study found neutralizing antibodies to SARS-CoV-2 in 40 percent of all white-tailed deer (Odocoileus virginianus) sampled.

In Michigan alone, 67 percent of free-living deer had immune markers of the coronavirus in their blood.

This is the first evidence of widespread exposure to SARS-CoV-2 in wildlife, and the results of this study are troubling.

Although no adverse health effects were found in any of the deer, the presence of specific antibodies in their blood suggests that they had recently struggled with the virus.

Scientists fear that by stealthily maintaining and spreading the pathogen, deer populations are allowing SARS-CoV-2 to adapt and evolve into new strains – ones that could re-infect humans years later with even greater transmissibility and severity than before.

After all, white-tailed deer in the U.S. often overlap with our species, whether in fieldwork, conservation, foraging, hunting or in sewage, providing an ideal pathway for the virus to spread back and forth.

“The geographic distribution of this species covers much of North America, and these animals are particularly abundant near urban population centers located in the eastern United States,” the authors write in their paper.

“Moreover, white-tailed deer can form social groups, a contact structure that can support intraspecific transmission of multiple pathogens.”

Ever since the global pandemic began, scientists have worried that a new coronavirus could pass from humans to another animal species, known as zoonotic leakage.

Last year, for example, an outbreak among farm-raised mink led to the mass culling of livestock in Europe and the United States. But unlike animals kept in captivity, infections among wild animals are not easily controlled.

That’s why scientists are so concerned about the latest research findings. If SARS-CoV-2 can indeed find refuge in the wild, this could make it extremely difficult to eradicate. If the virus adapts among other species and then reinfects humans, our vaccines may be much less effective in the future.

Recently, a seemingly healthy wild mink in Utah tested positive for SARS-CoV-2, becoming the first free-living animal to contract the virus. However, as scientists predicted, this was probably just the tip of the iceberg. Now the virus seems to have spread to wild deer as well.

If we want to be absolutely certain that these free-ranging animals are a reservoir for the new coronavirus, they must be tested for viral RNA, but the presence of antibodies in their blood suggests that they have somehow been exposed.

Previous laboratory studies have shown that white-tailed deer are highly susceptible to SARS-CoV-2, and that one infected individual of the species can infect another.

The new study suggests that similar spread can occur in the wild, although more research is needed to figure out how this happens.

The team got access to 385 wild white-tailed deer serum samples from January through March 2021, as well as 239 archived samples from 2011 through 2020, which they tested for antibodies to SARS-CoV-2.

Before the pandemic began in 2019, government researchers found no immune markers of the SARS-CoV-2 virus in wild deer blood. However, after the pandemic began, these antibodies began to appear more and more frequently.

In 2020, specific blood proteins for SARS-CoV-2 were detected in three deer. In the first three months of this year, however, nearly half of all 385 blood samples taken from deer in Michigan, Pennsylvania, Illinois and New York showed the same neutralizing antibodies.

Exactly how these deer contracted the virus remains to be seen. It could have passed directly from humans, or it could have been transmitted from livestock or wild animals in contact and then gotten to white-tailed deer.

Consequently, officials in the U.S. are calling for increased surveillance of wildlife, especially predators and scavengers that regularly interact with deer.

“If there is a common source of infection in deer, the same source could probably infect other animals,” virologist Arinjay Banerjee of the University of Saskatchewan, who was not involved in the study, told Nature.

Perhaps SARS-CoV-2 is penetrating wildlife faster than we have time to catch it.”

The study was published in the journal bioRxiv.

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