“Tiger at US zoo tests positive for coronavirus, becomes first animal to catch COVID-19,” an April 2020 headline proclaimed.
The story referred to a 4-year-old Malayan tiger, Nadia, who contracted COVID early in the pandemic, along with six other tigers at the Bronx Zoo, likely after being treated by a presymptomatic zoo employee.
It was the first in what would become a steady stream of stories about animals who, like most of us, have come down with COVID. Among the menagerie of animals that have, according to the US Centers for Disease Control and Prevention:
- Pets like cats, dogs, ferrets and hamsters.
- Zoo animals like lions, tigers, snow leopards, otters, hyenas, hippos and manatees.
- Mink that live on farms.
- Wildlife including dozens of white-tailed deer and mules, a black-tailed marmoset and a giant anteater.
Unfortunately, COVID is no exception to “zoonotic” diseases that animals have transmitted to humans, or vice versa. It is thought to have spread from a bat, pangolin or raccoon dog to humans, possibly via an intermediary such as a pet (although a controversial “leakage” hypothesis laboratory” has not been fully debunked).
Similar to COVID, the 2009 H1N1 “swine flu” pandemic is believed to have been caused by North American and European pigs mixing together, mixing flu strains. West Nile virus, which originates from arthropods and is transmitted by mosquitoes, established itself in New York in 1999 and has since become endemic in the United States. in monkeys, although it is thought to originate in rodents.
Animals most likely started the COVID-19 pandemic, as they have so many others, but their role in it has not gone away since. The pathogen now circulates through both populations, crossing and spilling over, even though such occurrences are relatively infrequent. And like humans, animals continue to shape the pandemic, as new variants and subvariants mutate in hosts with skin, fur, and feathers before attempting to leap into the larger population.
Scientists are monitoring the animal kingdom for signs of what is to come.
A host is a host
Scientists have recently started tracking the spread of COVID in animals on publicly available data dashboards. One, launched late last month by the Wildlife Conservation Society and Australian researchers from the University of Veterinary Medicine in Vienna, has so far documented 704 diagnoses of COVID-19 in animals worldwide, in 39 countries and 27 species.
Among the revelations:
- 117 cat and 110 dog infections have been documented in the United States
- Mink are among the most commonly identified animals with COVID. In Greece alone, 159 American mink have been diagnosed, in addition to almost 150 in Spain and 250 in Lithuania.
- Most animals were asymptomatic or exhibited respiratory symptoms. Mink are most likely to die.
- Omicron subvariants are the most common strains identified in animals, although cases of Delta have also been documented.
The risk of contracting COVID from animals is low, says Dr. Mary Montgomery, a clinician educator in the Division of Infectious Diseases at Brigham and Women’s Hospital, a Harvard-affiliated facility in Boston.
But it’s real. COVID entered humans from animals — possibly in several patients from multiple animal encounters in late 2019, according to a recent study — and it may reintroduce animals via humans in a process that scientists call “zoonotic transmission”.
Just as COVID can mutate in humans, it can mutate in animals. Thus, an animal with COVID could spawn a new variant or subvariant and pass it on to humans.
In a worst-case scenario, this new variant would be even more transmissible than Omicron’s currently dominant BA.5 subvariant and even more immuno-evasive, possibly even able to thwart antivirals like Paxlovid and monoclonal antibody treatments. administered in hospitals and outpatient clinics.
The most likely culprit in such a scenario could be a bird, due to its migratory nature.
“Birds can migrate and spread new pathogens rapidly,” says Montgomery. “And there are certainly many cases in the literature of other coronaviruses affecting birds.”
Among the researchers monitoring the avian population: Dr. Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark. He has created and maintains a number of COVID-related data dashboards, including one on COVID in animals, powered by data from GISAID, an international research organization that tracks changes in COVID and the virus. flu.
While the majority of animal cases identified worldwide have been in mink, deer and pets like cats and dogs, Rajnarayanan recently noted that COVID has already passed through the avian population. The first two reported cases were recently identified in swans in China.
Omicron appears more likely to infect chickens and turkeys than the Delta variant, he says, adding that avian crossbreeding could eventually have “big implications” like new mutations, widespread spread of the virus and impacts on human health. food supply.
“Everyone wants to focus on mammalian species,” he says. “Now the birds come into the picture. We want to monitor this much more closely.
Rajnarayanan would like to see the US Department of Agriculture facilitate more frequent testing of farm animals. He also thinks the agency should provide protective equipment to farmers to reduce the likelihood of transmission from farmers to farm animals, and vice versa.
“We’re almost in our third year, we don’t want this to go on forever,” he says.
Medical and veterinary professionals need to partner
As climate change continues, forcing animals and humans into more regular contact, fallout and fallout are inevitable – be it COVID, avian flu, or an agent pathogen still unknown to man – perhaps the next pandemic.
Montgomery champions the concept of “One Health”, which emphasizes that the health of people, animals, plants and their common environment are inexorably linked.
Vets and doctors used to train together before the advent of the automobile, which caused doctors to move to big cities with hospitals and vets in rural areas, where they were needed. to take care of the farm animals, she says. Harvard once housed a veterinary school, in addition to its medical school, and students trained together.
Such transdisciplinary collaboration is once again necessary if we are to finally get ahead of this pandemic and prevent the next one.
“We need to have the resources not just to think about human health, but to make sure we’re thinking about animal health,” she says, adding that humans often don’t care about diseases in animals – until what they penetrate humans.
“Sometimes we don’t think about prevention or early mitigation or containment. We only react when something has entered the human population. Awareness is the key here.
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