Deer have spread COVID to humans multiple times, researchers say

Americans have transmitted COVID-19 to wild deer hundreds of times, an analysis of thousands of samples taken from the animals has found, and people have also caught and spread mutated deer variants at least three times.

analysis published monday stems from the first year of a multi-year federal effort to study the virus as it has spread in US wildlife, led by the US Department of Agriculture’s Animal and Plant Health Inspection Service, or APHIS.

Scientists analyzed 8,830 samples taken from wild white-tailed deer in 26 states and Washington, DC, from November 2021 to April 2022, to study the COVID variants that had infected 282 of them.

By comparing virus sequences in deer with other publicly reported samples from human infection databases around the world, they were able to trace the likely spread of these variants between humans and animals.

A total of 109 “independent spillover events” have been identified, matching the viruses spotted in deer to the predecessors from which they likely originated in previously infected humans.

Several of these viruses still appear to mutate and spread between deer, including the concerning Alpha, Gamma and Delta variants that led to increased deaths earlier in the pandemic, long after these lineages were subsumed by the wave of variants. of Omicron which continue to dominate nationally.

Eighteen of the samples had no “genetically related human SARS-CoV-2 sequence in the same state”, thwarting efforts to find a precursor variant in humans.

“Overall, this study demonstrated that frequent introductions of novel human viruses into free-ranging white-tailed deer continued to occur, and that SARS-CoV-2 VOCs were able to persist in white-tailed deer even after these variants have become rare in the human population,” the study authors wrote.

Three had mutations that fit a distinctive pattern of first human-to-deer spillover, then later another so-called deer-to-human spillover. Two of these spill variants were in North Carolina and one in Massachusetts.

An investigation by the Centers for Disease Control and Prevention found three people infected with a variant of this hallmark deer mutation, along with a handful of zoo lions also infected with the same strain.

None of the humans said they had close contact with deer or the zoo.

Zoonotic diseases

APHIS researchers have been studying whether the white-tailed deer, among several American wildlife species, could potentially serve as a so-called long-term “reservoir species” to harbor the virus as it mutates its adaptations to widespread among deer.

A previous report from scientists in Canada found “a highly divergent lineage of SARS-CoV-2” that spread from deer to humans.

Government scientists are also concerned about how the virus could affect animals as it spreads between humans and wildlife.

“Deer regularly interact with humans and are commonly found in human environments – near our homes, pets, sewage and garbage,” said Professor Xiu-Feng Wan from the University of Missouri, author of the article, in a press release. release announcing the results.

The authors of the paper cited other examples of diseases spreading between humans and deer, such as a previous outbreak of bovine tuberculosis in deer. who was bound to local “supplementary feeding” efforts to sustain wild deer populations in Michigan.

The CDC has previously urged Americans to avoid close contact with wildlife and their droppings, both to minimize the spread of SARS-CoV-2 as well as other supposedly dangerous zoonotic diseases that spread between humans and animals.

“The potential for SARS-CoV-2, or any zoonotic disease, to persist and evolve in wildlife populations may pose unique public health risks,” Wan said.