New COVID Discoveries Emerging; Transmission Human to Animal

"When COVID came around, one of the things we were really concerned about was the possibility the virus could go from people to animals, because all of the evidence up until this point is very strong and suggests that it is a zoonotic virus."

"And then, it would change. Because when a virus gets into a new species, it has to adapt to it."

"And then it could jump back. And jumping back, the changes could make it so that it was either more infectious for people, or that the vaccines we have against it don't work against it because it has changed sufficiently."

"There is convincing information that, at least in parts of the U.S., there has been transmission from people to deer and within the deer population."

"Even in the last part of 2020, there was no evidence of the virus in the deer population. Then the numbers started to increase. What we don't know -- and this is the important thing -- is how it got from people to deer."

"Once we find out how they got infected, we'll get a better feel for which species are susceptible."

"It's early days. Right now, we don't know much about it. There's no need for panic right now."

Vikram Misra, professor of veterinary microbiology, biochemistry and health sciences, Western College of Veterinary Medicine, Unive4rsity of Saskatchewan 

"We would prefer not to see wildlife reservoirs. It could lead to infections in the human population."

"We know that mink are susceptible because of evidence in mink farms."

Jeff Bowman, provincial wildlife research scientist, adjunct professor, Trent University 

A deer is seen at the Michel-Chartrand Park in Longueuil, Que., on November 13, 2020. THE CANADIAN PRESS/Paul Chiasson

 

Researchers early this fall reported that COVID-19 had spread both suddenly and widely in the white-tailed deer population in the United States. Deer didn't appear to be dangerously infected and to the present no known transmission has occurred of SARS-CoV-2 from deer to people. But this is yet another mystery that science is faced with, and scientists want to know how it happened that COVID-19 was transmitted to deer in the wild.

Logic has it scientifically that if the virus travelled from humans into other animal species that had not previously been introduced to the virus a perceived danger exists it could establish itself into other species. More latterly three white-tailed deer were discovered in Quebec to be infected with the virus causing COVID-19. SARS-CoV-2 was confirmed to have been found for the first time in three free-ranging deer in the province.

The National Centre for Foreign Animal Disease revealed that the deer were among those sampled in the Estrie region of Quebec through a big game registration station. According to the Canadian Animal Health Institute, some 60 percent of all human diseases can switch from human to animal and from animal to human. About 74 percent of new emerging human infections over the past three decades have been "zoonotic"; which is to say, of animal origin.

Reports have come in from around the globe of animals being infected with the virus causing COVID, ranging from pets such as felines and canines, to farmed mink and zoo animals, ranging from gorillas to tigers to hyenas. The deaths of three rare snow leopards in a Nebraska zoo made headlines precisely for the reason that animal deaths caused by COVID infections have been rare occurrences. 

Researchers in Ontario last winter tested mink, raccoons, skunks and bats, finding no evidence of infection in any of the species, including wild mink. Information relating to the spread of the virus in wild deer remains sketchy, but discovering it in the deer in Quebec "emphasizes the importance of ongoing surveillance for SARS-CoV-2 in wildlife to increase our understanding about SARS-CoV on the human-animal interface", explains Environment and Climate Change Canada.

A research project to monitor the situation  among deer, muskrats, beavers and otters, piggybacking other wildlife studies will commence in Ontario this winter, advised research scientist Jeff Bowman. A coalition comprised of the Public Health Agency of Canada, the Ontario Ministry of Health, the Canadian Wildlife Health Cooperative and virologists at the Sunnybrook Health Sciences Centre in Toronto will be involved in the research.

 

Hunters are being warned to take extra precautions if they are handling deer carcasses, to protect themselves from any possible risk of transmission. (Paul Chiasson/The Canadian Press)

 

Veterinarians at Pennsylvania State University found active infections in 30 percent of deer tested across Iowa, making these cases reported in the United States deer population particularly perplexing. Mr. Bowman is of the belief that something quite unique exists relating to deer-human interaction, resulting in the cross-species infections.

Professor Misra and colleagues are in the development stages of a universal blood test to be used for wildlife to flag exposure to the virus. Tests have been validated to the present in hamsters and ferrets, but a universal test is envisaged that could create a system to routinely screen a wider variety of susceptible species. "Then we could be able to determine when this occurred and then follow it through", explained Dr. Misra.

Zoos have already seen vaccines used to protect vulnerable animals housed there. Dr. Misra, whose study is within bat populations with no known infections believes it is theoretically possible to create an "infectious vaccine" where some animals could be inoculated and they then could "spread" the vaccine to other animals making use of another virus as a vector. "But at this point, it's early days because we don't know which species to aim for. In rabies, for example, the vaccine could be placed inside bait. With deer, it would present with a little difficulty".

The biological traits of five thousand mammals have been analyzed by a team of scientists in the interests of creating a model to enable prediction of the capacity of certain species to transmit the virus and to be able to identify areas of overlap between habitat and COVID-19 hot-spots. Published by the Royal Society this fall, the study found 540 species with high zoonotic capacity -- including white-tailed deer.

According to Dr.Misra, COVID-19 is likely to remain in the mammal population. No evidence exists of infection in birds or reptiles, or in farm animals. However, researchers are maintaining an aware eye on water buffalo, domesticated in some parts of the world as an important source of milk protein. "It's early days. Right now, we don't know much about it. There's no need for panic right now", he stated.

Three white-tailed deer found to be infected with the virus that causes COVID-19 appeared healthy and showed no signs of the disease, according to Environment and Climate Change Canada. (Paul Chiasson/The Canadian Press)