Spread of COVID-19 In Deer Is Worrisome To Health Officials

Recent studies indicating that the COVID-19 virus is spreading throughout the white-tailed deer population in the United States has alarmed officials, but those same officials have said there is no indication yet that the deer have transferred the disease back to humans — although they concede that it is possible.

As a result, several states’ agencies — including New York — have issued stricter recommendations for hunters as we enter the winter deer hunting season. In addition, wildlife officials and the United States Department of Agriculture (USDA) — which conducted one of the studies — have called for stepped up surveillance and testing noting the alarming rate at which the disease has spread in the deer population, at the same time acknowledging the disease is apparently not harmful to the animals. Yet they are concerned about the possibility of the virus mutating in its new host, the possibility of the disease spreading to other animal species, and the possibility of disease “spillover” back into the human community.

“We didn’t know that this was happening until the studies were conducted,” Dr. Luis Marcos, an associate professor of clinical medicine in the Division of Infectious Diseases at Stony Brook University, said in a recent interview. But, said Dr. Marcos, the studies “offer more questions than answers.”

The initial study by the USDA’s Animal and Plant Health Inspection Service sampled 385 deer in January through March of this year from four states, including Michigan, Illinois, Pennsylvania and New York. Of those, 152, or about 40 percent, tested positive for antibodies for the SARS-CoV-2 virus.

Of the samples taken from deer in New York State, eight were taken from Suffolk County, and none of them showed evidence of antibodies to the COVID virus. But in upstate Onondoga County, nine of the 21 samples — or about 43 percent — tested positive.

In Illinois, only 7 percent tested positive, but in Pennsylvania, 44 percent were positive, and in Michigan, 67 percent were positive.

A study by researchers at Penn State University of 283 white-tailed deer samples from April through December 2020 in the state of Iowa indicated that about 33 percent tested positive for infection by the COVID virus. Alarmingly, noted the report, when looking at 97 samples taken from November 23, 2020, to January 10, 2021, 80 of them — or 82 percent — tested positive for the virus.

“This is the first direct evidence of SARS-CoV-2 virus in any free-living species, and our findings have important implications for the ecology and long-term persistence of the virus,” Suresh Kuchipudi, clinical professor of veterinary and biomedical sciences, and associate director of the Animal Diagnostic Laboratory at Penn State, said in a release from the university on November 3. “These include spillover to other free-living or captive animals and potential spillback to human hosts. Of course, this highlights that many urgent steps are needed to monitor the spread of the virus in deer and prevent spillback to humans.”

According to Vivek Kapur, professor of microbiology and infectious diseases at Penn State, while no evidence exists that SARS-CoV-2 can be transmitted from deer to humans, “hunters and those living in close proximity to deer may want to take precautions, including during contact with or handling the animals, by wearing appropriate personal protective equipment and getting vaccinated against COVID-19.”

An important difference in the protocols of the two studies is that the USDA investigation detected antibodies, indicating simply that the deer had been exposed to the virus and not necessarily infected, while the Penn State study examined the lymph nodes of the deer, showing clear evidence of actual infection.

To date, most of the samples used for the studies have come to researchers “opportunistically”; that is culled deer, deer recovered from accidents with vehicles, or deer that have been sampled for other diseases, such as chronic wasting disease, which there is evidence of on Long Island, and epizootic hemorrhagic disease, also found on Long Island.

The East End and the rest of the lower part of the state are in the middle of the fall/winter archery hunting season for deer and other big game, and January will bring the month-long shotgun season. In light of the recent studies, the State Department of Environmental Conservation, which oversees hunting and herd management programs, has added face covering to its list of recommendations for hunters when they field dress and handle deer this season.

The State of Wisconsin has gone a bit further, recommending, in addition to face masks, that hunters limit handling or cutting into the lungs, throat or nasal cavity of deer, and, if immunocompromised, consider asking for help in handling and processing the carcass.

In Quebec, where just last week authorities identified three white-tailed deer with the COVID virus, hunters have been urged to wear a mask if handling respiratory tissues or fluids from the deer, and the government has recommended those who come in close contact with deer wear a mask.

But the likelihood of deer passing the disease on to humans, especially in the wild, is very remote, said Stony Brook’s Marcos. “If the virus is living in the organs of the deer, in theory the hunter could get the virus,” said Marcos. “But in the open, the current, the air flow is so unstable that viruses would drop quickly. They could not stay in the air at all.

“It would be very unlikely,” he said, but added that if a hunter were to contract the virus from a deer, it would be evident in symptoms in about five days.

Marcos noted that the studies that have been done so far have detected evidence of the virus in the deer’s blood and, in the case of the Penn State study, in the animals’ lymph nodes. “Did they find it in the nose? We don’t know,” said Marcos, noting that it is through the nasal cavity that the disease is most frequently spread. “So, in theory it may be possible, but the studies have not shown whether it was in the saliva,” he said.

Animals passing the disease on to humans is not unheard of, especially considering it is believed the virus was first transmitted to humans via bats.

In November 2020, it was discovered that farm workers in Denmark had transferred the COVID virus into a population of commercially raised mink. When it was later discovered that the mink had then given a mutated version of the disease back to humans, the Danish government decided to cull 17 million of the industry’s mink in fur farms throughout the country.

It appears unquestionable that the deer so far tested received their infections or exposure to the virus through humans. Marcos pointed out that genomic sequencing of the deer samples were parallel to human samples, and in fact had not evolved to any large degree.

“They’re showing that the virus has not mutated greatly from the human virus,” even considering that it went from human to deer and then likely other deer, which Marcos took as a good sign. He suggested one reason for a lack of mutation or known transmission to humans is that deer may have a natural strong immune defense to the virus.

But the potential for future evolution of the virus in the deer hosts remains a concern. This is especially true when considering a population of wild deer that cannot practically be immunized or otherwise controlled.

Observations from the USDA’s EPHIS study expressed concern over the deer — and other species, such as mice and other rodents — becoming a “reservoir” for the virus and the potential for harm to the human population.

The virus, researchers wrote, “can infect multiple domestic and wild animal species. Thus, the possibility exists that new animal reservoirs of SARS-CoV-2 could emerge, each with unique potential to maintain, disseminate, and drive novel evolution of the virus. Of particular concern are wildlife species that are both abundant and live in close association with humans.”

Suburban deer, for example.

Suffolk County has a population of about 25,400 to 34,600 white-tailed deer, according the State DEC, with the great majority of them living on eastern Long Island, from Brookhaven to Montauk and Orient. That number is growing, and has expanded farther into more populated environments into western Suffolk and Nassau counties, despite efforts to cull the herd through nuisance deer permits which allow property owners to kill — or hire hunters to kill — deer on their property. And over the past decade, the DEC has extended the hunting season to encourage a greater culling of the herd.

With the growing population, it appears that the number of deer harvested has increased year to year, if just slightly. In 2020, the DEC reports that 4,525 deer were harvested in Suffolk County. In 2019, that number was 4,124, with 512 of them reported from East Hampton Town and 701 from Southampton Town. In 2018, the county total was 3,407, with 466 from East Hampton and 603 from Southampton. In 2017, the county total was 3,254, with 280 from East Hampton and 604 from Southampton.

But those numbers don’t reflect all the deer that are killed each year in Suffolk County, said Michael Tessitore, a hunter who operates a service based in Westhampton Beach that manages deer populations on private properties, and who represents a number of hunters who are brought in to cull herds largely through nuisance permits issued by the state.

Not reported, he said, were deer killed in car accidents, and the number of deer killed by hunters who operate without official state tags, or those who simply do not report their deer to authorities.

Hunters he works with, said Tessitore, have tags to shoot does, which hunters are encouraged to cull, and for which hunters can get additional tags throughout the season. But hunters also get access to private properties for hunting prize bucks, for which they are limited to two tags per season.

None of his hunters, he said, is concerned about catching the COVID virus from deer.

“I butcher deer meat almost daily, and I’m not worried about it,” said Tessitore, whose storefront near Gabreski Airport in Westhampton has a butchering facility where hunters are invited to bring their deer for processing.

Are his hunters considering wearing masks? “No one is even thinking about that,” he said, but added that “anytime you’re handling a wild animal, any animal, you should be careful.”

“If someone was to get COVID, how would you know it came from a deer?” he asked. “How would you know if it didn’t come from someplace else?”

Tessitore said most hunters never get close to a deer. “Only about 25 percent of hunters are even successful,” he said.

“It just seems, like, how is this practical, how is a hunter going to get close enough?” he asked. “I’m not kissing the deer — I’m not going to give it CPR.” The USDA does advise, however, that the virus can be shed through feces as well as saliva.

But Tessitore considered the possible pathways for the spread of the virus. “Where do you think the deer got it from?” he asked, then answering his own question suggested one culprit might be deer farms, of which there are several in upstate New York.

Typically, he said, deer raised on farms for venison sold to markets and restaurants, or for other products, are penned in areas that are in close proximity to other wild areas. “But they’re not double fenced,” he said, and noted that wild deer can come up to the fence and interact with the farm-raised cervids.

Indeed, in answer to one of the biggest questions raised by the studies, the USDA recently observed that “several transmission routes are possible for exposure of wild deer to SARS-CoV-2. In the case of outbreaks in farmed mink, direct transmission of the virus from infected humans to mink is the only definitive transmission route identified to date. Multiple activities bring deer into direct contact with people, including captive cervid operations, field research, conservation work, wildlife tourism, wildlife rehabilitation, supplemental feeding, and hunting.”

The Centers for Disease Control and Prevention, along with the USDA and other agencies, has said there is no evidence that humans can contract the COVID virus from eating cooked venison or other game meat, nor is there evidence that the virus sickens or kills the deer.

It does advise, however, that hunters not allow contact between the carcass and domestic animals such as pets and hunting dogs; don’t harvest animals that appear sick or are found dead; wear rubber or disposable gloves when interacting with a deer carcass; and clean knives and other equipment thoroughly with soap and water, among other recommendations.

Further research and surveillance is required to determine the potential for deer as hosts to facilitate mutations of the virus and whether the virus can be transmitted from deer to humans, authorities agree.

Based on the various recent studies, the USDA’s APHIS will begin a phased, multi-year approach this winter to further understand the impacts of the virus on deer-to-human and animal health, Tanya Espinosa, public affairs specialist for USDA/APHIS wrote in a statement to this newspaper last week.

“The goals are to determine how widespread the virus is in white-tailed deer populations in the United States and if deer can serve as a reservoir for the virus, potentially leading to new virus variants that may impact the health of deer, other animals, and people,” she wrote. “At this time, APHIS is reaching out to state fish and game agencies in multiple states to see if they are interested in participating in the effort.”

The plan moving forward calls for the USDA to use $300 million in American Rescue Plan Act funds to conduct surveillance for SARS-CoV-2 in susceptible animals and build an early warning system to alert authorities to potential animal-to-human disease threats.

“The immediate focus is on expanding surveillance for SARS-CoV-2 to a wide range of animal species, increasing diagnostic testing capability and capacity and conducting One Health investigations of new animal detections and exposures,” Espinosa wrote.

“We do want to ensure that people know that currently, there is no evidence that animals play a significant role in spreading SARS-CoV-2, the virus that causes COVID-19, to people,” she wrote. “The risk of animals, including deer, spreading COVID-19 to people is low.”