“The tiger at the U.S. zoo tests positive for coronavirus, becoming the first animal to contract COVID-19,” the headline said in April 2020.
The story related to a 4-year-old Malayan tigress, Nadia, who contracted COVID at the start of the pandemic, along with six other tigers at the Bronx Zoo – presumably after being cared for by a predictive zoo worker.
It was the first ever steady stream of stories about animals that, like most of us, contracted COVID. Among the animal menageries that, according to the U.S. Centers for Disease Control and Prevention, have:
- Animals such as cats, dogs, ferrets, and hamsters.
- Zoo animals such as lions, tigers, snow leopards, otters, hyenas, hippos, and manatees.
- Minks that live on farms.
- Wildlife, including dozens of white and mule deer, black-tailed marmoset and giant anteater.
COVID is not the infamous exception to zoonoses that animals have transmitted to humans and vice versa. It is believed to have transmitted from a bat, pangolin or raccoon dog to humans, possibly through an intermediary such as a pet (although the controversial “lab leak” hypothesis has not been completely refuted).
As with COVID, the 2009 H1N1 “swine flu” pandemic is believed to have been caused by mixing North American and European pigs, mixing flu strains. The West Nile virus, which is arthropod-borne and transmitted by mosquitoes, established itself in New York in 1999 and has since become endemic in the United States. in monkeys, although it is believed to be derived from rodents.
The animals most likely triggered the COVID-19 pandemic because they have so many others – but their role in it hasn’t disappeared afterwards. The pathogen is now circulating in both populations, passing through and spilling back out, even though such events are relatively rare. And like humans, animals continue to shape the pandemic as new variants and sub-variants mutate in hosts with skin, fur, and feathers before trying to make their way into the wider population.
Scientists are watching the animal kingdom for signs of what’s coming next.
The host is the host
Scientists recently began tracking the spread of COVID in animals on publicly available dashboards. One, launched late last month by the Wildlife Conservation Society and Australian scientists at 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:
- In the US, 117 cat infections and 110 dogs have been documented
- Minks are among the most commonly identified animals with COVID. In Greece alone, 159 American mink have been diagnosed, almost 150 in Spain and 250 in Lithuania.
- Most animals were asymptomatic or experienced respiratory symptoms. Minks are the most vulnerable to death.
- Omicron sub-variants 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 clinical educator at the Infectious Disease Unit at Brigham and Women’s Hospital, a facility linked to Harvard in Boston.
But it is real. According to recent research, COVID has made its way into humans from animals – perhaps in many patients from multiple animal encounters in late 2019 – and may re-enter animals via humans in a process scientists call ‘zoonotic transmission’.
Just as COVID can mutate in humans, it can mutate in animals. In this way, the COVID animal can spawn a new variant or sub-variant and transfer it back to humans.
At worst, this new variant would be even more infectious than the current dominant sub-variant Omicron BA.5 and even more immune to the immune system – perhaps even capable of outsmarting antiviral drugs such as Paxlovid and treatment with monoclonal antibodies in hospitals and outpatient settings.
Birds may be the most likely culprit in this scenario, due to their migratory nature.
“Birds can migrate and spread new pathogens quickly,” says Montgomery. “And there are definitely many cases of other coronaviruses targeting birds in the literature.”
Researchers keeping an eye on the bird population include Dr. Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark. He created and maintains a series of COVID data dashboards, including one on COVID in animals, filled with data from GISAID, an international research organization that tracks changes in COVID and the influenza virus.
While the majority of animal cases identified worldwide are in mink, deer, and pets such as cats and dogs, Rajnarayanan recently noted that COVID has already spread to the bird population. The first two reported cases were recently identified in swans in China.
Omicron appears to be more likely to infect chickens and turkeys than the Delta variant, he says, adding that crossbreeding could eventually have “big implications” such as new mutations, widespread spread of the virus, and impacts on food supply.
“Everyone wants to concentrate on a species of mammals,” he says. “Now birds appear in the painting. We want to monitor it much more closely. “
Rajnarayanan would like the US Department of Agriculture to facilitate more frequent livestock testing. He also believes that the agency should provide farmers with protective equipment to reduce the likelihood of transmission of the virus from farmers to livestock and vice versa.
“We’re almost in our third year – we don’t want this to last forever,” he says.
Medical and veterinary professionals must be partners
As climate change continues, forcing animals and humans to come into contact more regularly, there is sure to be spread and spread – be it COVID, avian flu, or a pathogen not yet known to man – perhaps the next pandemic.
Montgomery advocates the “One Health” concept, which emphasizes that the health of humans, animals, plants and their shared environment are inextricably linked.
Vets and doctors trained together prior to the appearance of the car, which caused doctors to relocate to large cities with hospitals and vets to relocate to rural areas where they were needed to care for farm animals. Harvard was once home to a vet school, in addition to medical school, and the students trained together.
Such transdisciplinary cooperation is needed again if we are to finally get ahead of this pandemic – and prevent another.
“We need to have resources to not only think about human health, but also to make sure we think about animal health,” he says, adding that people often don’t care about animal diseases – until they get into humans.
“Sometimes we don’t think about prevention, early alleviation or limitation. We only react when something enters the human population. Awareness is key here. “
Register on Features of fortune email list so you don’t miss our greatest features, exclusive interviews and investigations.