N.B. monitors deer for COVID-19 after study finds 'nearly extinct' variants mutating
New Brunswick is keeping an eye out for COVID-19 strains in white-tailed deer after a recent study in the U.S. found mutations of SARS-CoV-2 variants in deer that no longer circulate among people, raising questions about whether the animals could transmit the virus back to people.
Researchers from Cornell University looked at more than 5,000 lymph node samples from free-ranging hunter-harvested white-tailed deer collected in the State of New York between 2020 and 2022.
They detected three major variants of concern — Alpha, Delta, and Gamma — several months after their last detection in humans.
"Interestingly, the viral sequences recovered from [white-tailed deer] were highly divergent from SARS-CoV-2 sequences recovered from humans, suggesting rapid adaptation of the virus in [white-tailed deer]," states the study, published Jan. 31 in the Proceedings of the National Academy of Sciences (PNAS).
"The impact of these mutations on the transmissibility of the virus between [white-tailed deer] and from [white-tailed deer] to humans remains to be determined."
It's also unclear whether these variants will disappear in deer over time or whether they could spread to other wildlife.
"These findings highlight the need to establish surveillance programs that will allow continuous monitoring of the circulation, distribution, and evolution of SARS-CoV-2 in [white-tailed deer] populations," says the study.
67 recent N.B. deer samples negative
The New Brunswick Department of Health is "working collaboratively with its colleagues in the Department of Natural Resources and Energy Development to monitor the situation," spokesperson Adam Bowie said in an emailed statement.
He did not provide any details.
Bowie did note that none of the recently harvested deer in the province that were nasally swabbed tested positive.
The Department of Natural Resources collected nasal swab samples from 67 hunter-harvested white-tailed deer, according to spokesperson Nick Brown.
He did not say from which region or regions the samples were collected.
The department collected the samples at the request of Environment and Climate Change Canada, Brown said. "Various provincial jurisdictions in Canada were contacted to participate in the testing," he said in an emailed statement.
CBC requested more information from the federal department Tuesday, but did not receive a response.
Virus detected in N.B. deer in April
The presence of SARS-CoV-2, the virus that causes COVID-19, was confirmed in New Brunswick deer in April.
SARS-CoV-2 was detected in a sample taken from a free-ranging white-tailed deer in the Saint John region, Environment Canada had announced.
The sample was collected on Jan. 24, according to the Canadian Animal Health Surveillance System, a division of the National Farmed Animal Health and Welfare Council.
It was the first positive case detected in an animal in Atlantic Canada, according to the website.
Deer could serve as a 'reservoir' for virus
White-tailed deer are the most abundant large mammal in North America.
Over the course of the pandemic, deer have become infected with SARS-CoV-2 through ongoing contact with humans. Although the pathways for transmission of the virus from humans to white-tailed deer remain largely unknown, human activities such as feeding deer or baiting deer for hunting could provide opportunities, according to the researchers.
The Alpha, Delta, and Gamma variants were likely transmitted to the deer before going "nearly extinct" in people, according to the study. Sequencing of the deer samples found up to 80 mutations in some cases, compared to the strains found in people.
"A virus that emerged in humans in Asia, most likely after a spillover event from an animal reservoir into humans, apparently, or potentially, has now found a new wildlife reservoir in North America," Diego Diel, associate professor of population medicine and diagnostic sciences at Cornell, said in a news release about the study.
It is one of the most comprehensive studies to date to assess the prevalence, genetic diversity and evolution of SARS-CoV-2 in white-tailed deer, according to the news release.