Free-living animals can act as a reservoir for the virus, allowing it to multiply and mutate into variants with increased transmissibility and virulence, before spilling back into the human population
Author of the article: Devika Desai
Publishing date: Nov 12, 2021
Nearly one-third of Iowa deer are infected with SARS-CoV-2 virus,
which causes COVID-19 in humans, a study has found.
PHOTO BY GETTY IMAGES
With COVID-19 caseloads on the decline and vaccines rolling out around the world, nations have begun preparations for the next phase of the pandemic — learning to live with the virus.t
However, we may not be fully in the clear, scientists say after a study found the first evidence of animals transmitting the virus in the wild, with troubling implications for the spread of the disease and emergence of new variants.
Released on November 6, the preprint study found that one-third of the white tail deer population in Iowa over the past nine months has tested positive for SARS-CoV-2 — the virus that causes COVID-19 in humans — indicating that not only can deer catch the virus from humans but can also transmit it within their population in overwhelming numbers.
The study has not yet been peer-reviewed or published.
The transmission, it added, most likely resulted from “multiple zooanthroponotic spillover events” and “deer-to-deer transmission”, arising from herds in close proximity to humans.
The analysis was prompted by a recent report that found 40 per cent of free-living white-tailed deer in the U.S. contained antibodies against the virus.
Researchers were still “astonished” by the high viral loads detected in the animals, said Dr. Suresh Kuchipudi, clinical professor of virology at Penn State and the coauthor of the study.
“What was certainly surprising is the level of positivity we saw,” he said. “The amount of virus we detected in each of the animals was quite astonishing. We weren’t expecting that.”
Kuchipudi couldn’t say whether the deer displayed symptoms of the virus, instead pointing to the results of an earlier analysis conducted by Kansas State University researchers on adults and fawns, in which they injected the virus into healthy deer. While those animals didn’t appear to be affected by the virus, Kuchipudi acknowledged that environmental factors affecting health, access to resources could alter those results in the wild.
“We don’t know (if) the deer will actually express or exhibit any symptoms in the natural settings,” he said. “But based on the experimental set, infections, we know that they do not show any clinical symptoms.”
Can humans catch the virus from the infected deer?
The study, Kuchipudi acknowledged, comes with its ‘limitations’ and it could not say whether people living near herds or hunting the deer could catch the virus from the animals.
But it’s entirely possible, he said, pointing to studies done on infected mink populations that showed the virus “spilling back” into human populations in contact with the infected animals.
“Based on what we know about viruses when they spill into animals … the possibility of spilling back into humans cannot be ruled out,” he said.
Which could make learning to live with the virus more complicated than originally hoped. For one, it’s entirely possible that Iowa deer aren’t the only animals getting infected with the virus.
An analysis conducted in Ohio also found a similar level of infectivity among white-tailed deer. Previous studies in general have found that several animal species could be potentially susceptible to the virus, including cats, dogs, pumas, gorillas and snow leopards in zoos, and farmed mink.
A week ago, hyenas at the Denver zoo recently tested positive , marking the first confirmed cases in those animals.
The biggest concerns lay in what we don’t know about the virus transmission among wild animals, Kuchipudi said. Left uncontrolled, the virus could jump from one host to another and in the process, undergo mutations long enough to create new variants, some of which “could undermine the existing vaccines.”
“Now the chances of virus mutation has become twice as complicated because now it is also happening, at least in one animal species …. and perhaps in other animals that we do not know yet,” he said.
Many wild animal species, the study explained, already harbour a number of endemic coronaviruses, presenting all the more opportunities for a residing SARS-CoV-2 virus to ‘recombine and acquire or evolve increased fitness traits such as increased virulence, transmissibility, pathogenicity, and immune evasion.”
In other words — a virus that can freely circulate among animals is much harder to eradicate among humans.
Which means governments and infectious disease experts are now tasked with a new challenge two years into the pandemic — assessing just how widespread the virus is and the risk that arises from that. “What other animals (in the vicinity) could be getting infected,” Kuchipudi asked.
The evidence for virus spread within the free-living animal population also highlights the importance of the ‘One Health’ approach, a concept that advocates the need to consider animal, human and environmental health when fighting emerging infectious diseases. “In order to protect human health, we must also protect animal and environmental health,” Kuchipudi said. “But this should be done in a concerted effort rather than silos that do not talk to each other.”
With COVID-19 caseloads on the decline and vaccines rolling out around the world, nations have begun preparations for the next phase of the pandemic — learning to live with the virus.t
However, we may not be fully in the clear, scientists say after a study found the first evidence of animals transmitting the virus in the wild, with troubling implications for the spread of the disease and emergence of new variants.
Released on November 6, the preprint study found that one-third of the white tail deer population in Iowa over the past nine months has tested positive for SARS-CoV-2 — the virus that causes COVID-19 in humans — indicating that not only can deer catch the virus from humans but can also transmit it within their population in overwhelming numbers.
The study has not yet been peer-reviewed or published.
The transmission, it added, most likely resulted from “multiple zooanthroponotic spillover events” and “deer-to-deer transmission”, arising from herds in close proximity to humans.
The analysis was prompted by a recent report that found 40 per cent of free-living white-tailed deer in the U.S. contained antibodies against the virus.
Researchers were still “astonished” by the high viral loads detected in the animals, said Dr. Suresh Kuchipudi, clinical professor of virology at Penn State and the coauthor of the study.
“What was certainly surprising is the level of positivity we saw,” he said. “The amount of virus we detected in each of the animals was quite astonishing. We weren’t expecting that.”
Kuchipudi couldn’t say whether the deer displayed symptoms of the virus, instead pointing to the results of an earlier analysis conducted by Kansas State University researchers on adults and fawns, in which they injected the virus into healthy deer. While those animals didn’t appear to be affected by the virus, Kuchipudi acknowledged that environmental factors affecting health, access to resources could alter those results in the wild.
“We don’t know (if) the deer will actually express or exhibit any symptoms in the natural settings,” he said. “But based on the experimental set, infections, we know that they do not show any clinical symptoms.”
Can humans catch the virus from the infected deer?
The study, Kuchipudi acknowledged, comes with its ‘limitations’ and it could not say whether people living near herds or hunting the deer could catch the virus from the animals.
But it’s entirely possible, he said, pointing to studies done on infected mink populations that showed the virus “spilling back” into human populations in contact with the infected animals.
“Based on what we know about viruses when they spill into animals … the possibility of spilling back into humans cannot be ruled out,” he said.
Which could make learning to live with the virus more complicated than originally hoped. For one, it’s entirely possible that Iowa deer aren’t the only animals getting infected with the virus.
An analysis conducted in Ohio also found a similar level of infectivity among white-tailed deer. Previous studies in general have found that several animal species could be potentially susceptible to the virus, including cats, dogs, pumas, gorillas and snow leopards in zoos, and farmed mink.
A week ago, hyenas at the Denver zoo recently tested positive , marking the first confirmed cases in those animals.
The biggest concerns lay in what we don’t know about the virus transmission among wild animals, Kuchipudi said. Left uncontrolled, the virus could jump from one host to another and in the process, undergo mutations long enough to create new variants, some of which “could undermine the existing vaccines.”
“Now the chances of virus mutation has become twice as complicated because now it is also happening, at least in one animal species …. and perhaps in other animals that we do not know yet,” he said.
Many wild animal species, the study explained, already harbour a number of endemic coronaviruses, presenting all the more opportunities for a residing SARS-CoV-2 virus to ‘recombine and acquire or evolve increased fitness traits such as increased virulence, transmissibility, pathogenicity, and immune evasion.”
In other words — a virus that can freely circulate among animals is much harder to eradicate among humans.
Which means governments and infectious disease experts are now tasked with a new challenge two years into the pandemic — assessing just how widespread the virus is and the risk that arises from that. “What other animals (in the vicinity) could be getting infected,” Kuchipudi asked.
The evidence for virus spread within the free-living animal population also highlights the importance of the ‘One Health’ approach, a concept that advocates the need to consider animal, human and environmental health when fighting emerging infectious diseases. “In order to protect human health, we must also protect animal and environmental health,” Kuchipudi said. “But this should be done in a concerted effort rather than silos that do not talk to each other.”
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