Coronavirus infections increase among deer in US, new study shows

Preface

In August 2021, China Environment News reported that samples collected by Canadian virologists showed that “one-third of white-tailed deer, a familiar sight on US lawns and golf courses, in the north-eastern United States have antibodies against SARS-CoV-2 — a sign that they have been infected with the virus.” See ‘Corona virus rife in common US deer‘.

Earlier peer reviewed research published in March 2021 in the Journal of Virology confirmed that deer had been shown to shed the virus by the nasal secretion and faeces.

Scientists were concerned about the emergence of new animal ‘reservoirs’ — animal populations that harbour SARS-CoV-2. A pool of infected animals could provide a refuge where the virus could evolve in ways that threaten vaccine efficacy. 

Of particular concern is the US cultural practice of “backyard” hunting and consuming millions of wild animals each year, without adequate public health regulation.

There are estimated to be over 30 million wild white-tail deer in the US, and white-tails are the most popular big-game species hunted in North America. During the early 1900s, the population was almost hunted to extinction in much of the US, but the population has bounced back.

According to the American Hunter, each US deer hunting season 6.2 million deer are killed by hunters, and there are 10.1 million deer hunters in the US.

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Over 80% of deer in the new study tested positive for COVID:
Is this a reservoir for the virus to continually circulate ?

Concerns are rising after another recent study from the US found that even more white-tailed deer had tested positive for SARS-CoV-2, the virus responsible for COVID-19.

A new study released on biorxiv.org, an online preprint repository for the biological sciences, has found that
94 percent of sampled deer in the U.S. state of Iowa from April to November 2020 tested positive for active SARS-CoV-2 infection. Such a high level of virus detection led researchers to conclude a likely result “from multiple human-to-deer spillover events and deer-to-deer transmission.”

The new study, posted on bioRxiv on November 1, examined nearly 300 samples collected from deer across the state of Iowa during the peak of human COVID-19 infection in 2020. The samples — extracted from deer retropharyngeal lymph nodes, which are located in the head and neck — had been collected by the Iowa Department of Natural Resources as part of its routine statewide Chronic Wasting Disease surveillance program. The team tested the samples for SARS-CoV-2 viral RNA using a real-time reverse transcription polymerase chain reaction (RT-PCR) assay, which provides direct evidence of infection with the virus.

“We found that 80% of the sampled deer in December were positive for SARS-CoV-2, which proportionally represents about a 50-fold greater burden of positivity than what was reported at the peak of infection in humans at the time,” said Professor Suresh Kuchipudi, Chair in Emerging Infectious Diseases, at Pennsylvania State University. “The number of SARS-CoV-2 positive deer increased over the period from April to December 2020, with the greatest increases coinciding with the peak of deer hunting season last year.”

The team also sequenced the complete genomes of all the positive samples from the deer and identified 12 SARS-CoV-2 lineages, with B.1.2 and B.1.311 accounting for about 75% of all samples.

“The viral lineages we identified correspond to the same lineages circulating in humans at that time,” said Kapur. “The fact that we found several different SARS-CoV-2 lineages circulating within geographically confined herds across the state suggests the occurrence of multiple independent spillover events from humans to deer, followed by local deer-to-deer transmission. This also raises the possibility of the spillback from deer back to humans, especially in exurban areas with high deer densities.”

Jennifer Ramsey, wildlife veterinarian for Montana Department of Fish, Wildlife and Parks (FWP), was quoted by the Billings Gazette newspaper Monday as saying that a recently released study, which found about one-third of 283 captive and free-ranging deer had tested positive for the infection, rose concerns about deer being a reservoir for the virus to mutate.

“There’s a lot of uncertainty about how deer are getting exposed, and what this will mean for wildlife and humans over time,” she said.

“What’s the highlight of this research is that this is a free-ranging animal we don’t have reason to suspect has any intimate human contact,” Rachel Ruden, a coauthor of the paper and member of the Iowa State College of Veterinary Medicine, told the Duluth News Tribune. “But they’re still getting this infection.”

Previously, antibodies were found in 40 percent of the tested white-tailed deer from January to March 2021 across four U.S. states, according to a report published by the Proceedings of the National Academy of Sciences.

Then later in August, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) confirmed the world’s first case of infected white-tailed deer in Ohio.

The findings suggest that white-tailed deer may be a reservoir for the virus to continually circulate and raise concerns of emergence of new strains that may prove a threat to wildlife and, possibly, to humans. Although there is no evidence as yet of deer spreading the virus back to humans, the high population density of over 30 million white-tailed deer in the U.S. and their strong human interactions, particularly with hunters and farmers, could make eradicating the pathogen even more difficult.

SOURCES:

SciTech Daily, 09-Nov-2021. https://scitechdaily.com/over-80-of-deer-in-study-test-positive-for-covid-they-may-be-a-reservoir-for-the-virus-to-continually-circulate/

CGTN, 09-Nov-2021. https://news.cgtn.com/news/2021-11-09/Coronavirus-infection-found-in-white-tailed-deer-in-the-U-S–152UOKLZ4pq/index.html