Health Care

Could new strains of COVID evolve in farm animals or pets?

It appears no one is safe from severe acute respiratory coronavirus 2 (SARS-CoV-2). Given that SARS-CoV-2 likely developed in bats and later transmitted to humans in Wuhan, China, there has been concern over animals infecting humans. But more evidence has shown that humans are more likely to infect animals — from hamsters, gorillas to the domestic cat.

Most animals infected with SARS-CoV-2 do not develop serious illnesses like humans. But with the coronavirus evolving to become more contagious and deadly, there is a chance animals get infected and become a breeding ground for more variants.

Sarah L. Caddy, a Clinical Research Fellow in Viral Immunology and Veterinary Surgeon at the University of Cambridge, says that the possibility is likely. In collaboration with The Conversation, Dr. Caddy published an article on the World Economic Forum website that discussed the likelihood of new variants emerging from an animal’s coronavirus infection.

Image Credit: Garetsworkshop / Shutterstock

Two factors needed to make a variant

Variants require an opportunity to mutate. They require a high number of infections with a good number of chronic infections in immunocompromised bodies. Doing so allows the virus the time to find a beneficial mutation that makes it more transmissible or resilient against the immune system.

Evidence of animal-related SARS-CoV-2 variants

Dr. Caddy says the chances of the virus evolving in pets and going unnoticed is unlikely. In several preprint studies, researchers have randomly sampled household pets and found high antibody rates in the tested animals. In these studies, only a tiny minority of animals tested positive for SARS-CoV-2 or had these antibodies.

“So it’s reasonably safe to say that our household pets are unlikely to be acting as a significant reservoir of ongoing infections that could allow new variants to emerge,” wrote Dr. Caddy.

While most studies on coronavirus infections in animals have been largely studied in cats and dogs, there is evidence it also occurs in wildlife species such as deer mice and the white-tailed deer.

One animal of concern is minks. In May 2020, scientists found minks infected with SARS-CoV-2 and were able to transmit the virus back to humans. In Denmark, new SARS-CoV-2 variants emerged in November 2020 and were traced back to minks. Fortunately, the variants were contained, and mink infections were brought under control.

Close up adult Mink. Image Credit: Gallinago_media / Shutterstock

Close up adult Mink. Image Credit: Gallinago_media / Shutterstock

Given the previous crisis, minks appear to be the animal most likely to be under constant surveillance of new variants.

Immunosuppression in animals allows a possible, but unlikely, viral evolution

Like any virus, SARS-CoV-2 thrives in bodies with weak immune systems. While coronavirus infections in animals are less severe, are their host bodies sick enough to help the virus evolve?

Animals appear to get less severe of infection than humans. As a result, they don’t need the extensive hospitalization that would be needed for the virus to evolve into another variant.

For wildlife animals, having a weak immune system would threaten their overall existence. “As for immunosuppression in other animals, such as wildlife, this would be a significant survival disadvantage. It’s unlikely that animals with compromised immune systems would survive long enough for much evolution of an acute virus like SARS-CoV-2 to happen,” wrote Dr. Caddy.

Although, there has been preliminary data suggesting animals can develop minor SARS-CoV-2 mutations. More evidence is needed, but this indicates evolving variants in animals is a possibility.

Staying wary of future infections

Dr. Cady suggests strict monitoring on animals, especially those with close proximity and exposure to humans, such as pets and farm animals.  

“Moving forwards, it’s essential that we continue surveillance for SARS-CoV-2 in all manner of animal populations.”

While there is no evidence of animal-related variants, it’s a possibility scientists cannot afford to rule out. Moreover, if there is evidence of natural animal-animal spread or chronic infection in animals, these measures would need to be rapidly implemented to avert another crisis.

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