In the forests of northern Minnesota, researchers are sneaking into the dens of hibernating black bears, capturing deer in nets, and snaring wolves and moose for a quick snout, all in an effort to track the spread of SARS-CoV-2, the virus that causes Covid-19, in wildlife, writes Laura Ungar in an article for the Associated press.
The coronavirus pandemic has highlighted how closely animal and human health are intertwined. Although the exact origins of the virus have not been identified, researchers suspect that it may have jumped from bats to humans, either directly or via an intermediate animal vector. Although SARS-CoV-2 is known to infect animal species, the Covid-19 pandemic is caused by human-to-human transmission. While current research shows that wildlife does not play a significant role in the spread of the virus to humans, experts are still concerned about the spread of the virus between animal populations, which could facilitate the emergence of new variants of the virus.
Last month, the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO) and the Organization for Animal Health, formerly the Office International des Epizooties (OIE ), published a joint statement calling on global wildlife agencies to prioritize surveillance for SARS-CoV-2 infections in wild animals to prevent the formation of animal reservoirs. In a tank, the virus can mutate and emerge like different strains. So far, domestic animals, big cats, mink, ferrets, North American white-tailed deer and great apes have been observed infected with the virus. According to the statement, cases of farmed mink and pet hamsters have been shown to be able to infect humans with SARS-CoV-2.
“If the virus can establish itself in a wildlife reservoir, it will still be there with the threat of spreading into the human population,” Matthew Aliota, an emerging pathogen biologist at the University of Minnesota who is involved in monitoring efforts in the state, says AP. After taking the animal’s nose, biologists send the samples to Aliota’s lab in St. Paul, Minnesota. Test results can reveal which animals are infected and could spread the virus to other woodland creatures, such as red foxes and raccoons, AP reports.
EJ Issac, a fish and wildlife biologist at the reserve home to Grand Portage Ojibwe, told AP he expects the stakes to be higher this spring when animals wake up from hibernation and mingle with other animals and roam around different areas.
Currently, the fauna of at least 24 US states have contracted the virus. The white-tailed deer appears to be an important potential reservoir species. University of Pennsylvania microbiologist Andrew Marques, co-author of the study, said NPR’s Ari Daniel that the rate of transmission is “absolutely staggering when you consider the rate of positivity in humans”. (In March, when the study was published, coronavirus rates in a city like Philadelphia were around 3% in humans, per NPR.)
Between September 2020 and January 2021, researchers in Iowa tested 151 wild whitetail deer and 132 captive deer, according to a study published in PNAS in January. Of these, 33% tested positive for SARS-CoV-2. During the same period, the United States Department of Agriculture collected 481 samples from deer in Illinois, New York, Michigan and Pennsylvania, as well as found about a third of these deer had anti-coronavirus antibodies present in their systems.
More recently, in the fall and winter of 2021, researchers from Pennsylvania also identified a 20% coronavirus positivity rate in deceased white-tailed deer that were hunted or involved in collisions with vehicles, per NPR; both of which are cases where human-animal interaction is more likely. They were also able to sequence the genome of seven samples and found that the Delta strain was present, which marked the first observations of the lineage in deer, according to the study.
A Canadian study published on the preprint server bioRxiv in February of this year identified a person who may have contracted a mutated strain of the virus from an infected white-tailed deer, per AP. This study is currently undergoing peer review by a group of external experts, according to the WHO statement.
“We are encroaching on animal habitats like we have never done before in history,” Aliota told AP. “Wild animal spillover events onto humans will, unfortunately, I expect to increase in both frequency and scope.”