COVID-19 virus detected in 6 backyard animals – and humans are the cause

With cases on the rise, COVID-19 seems to be everywhere right now. But did you know the virus could also be literally lurking in your backyard? A new study by Virginia Tech scientists has discovered SARS-CoV-2 in six of Virginia’s most recognizable animal species, many of which are found across the United States.

We’ve long known that a human with COVID-19 can pose a risk to their pets. Two domestic cats were the first pets to test positive for the virus in the United States in early 2020, and the latest guidance from the Centers for Disease Control and Prevention (CDC) suggests that dogs, hamsters, and ferrets may also be at risk.

Many wild species and others held in zoos and sanctuaries have also been reported infected, leading the Virginia Tech team to wonder how widespread the virus might be among local wildlife.

“This study was really motivated by the recognition of a significant gap in our knowledge about SARS-CoV-2 transmission in the broader wildlife community,” assistant professor of biological sciences Joseph Hoyt, one of the corresponding authors, said in a statement.

They sampled 23 species and detected SARS-CoV-2 RNA in six of them: the deer mouse, the Virginia opossum, the raccoon, the marmot, the cottontail rabbit and the eastern red bat. A total of 798 nasal and oral swabs were collected between May 2022 and September 2023, either from animals captured in the wild and then released or from animals treated in rehabilitation centers. An additional 126 blood samples were also collected from six species.

The researchers wanted to compare animals in areas with more or less frequent human contact, from remote rural areas to our backyards. The data suggest that the virus has spread to wildlife populations living in areas with high human activity.

“The virus can jump from humans to wildlife when we come into contact with them, like a hitchhiker switching vehicles to a new, more suitable host,” said Carla Finkielstein, co-corresponding author and professor of biological sciences. “The goal of the virus is to spread to survive. The virus aims to infect more humans, but vaccines protect many humans. So the virus turns to animals, adapts and mutates to thrive in the new hosts.”

We often talk about the risks of virus transmission from animals to humans, especially when it comes to the origins of COVID-19, but we rarely stop to consider the reverse scenario. A recent study found that viruses jump from humans to animals more often than the other way around. This data now shows that we have helped spread SARS-CoV-2 to more animal species than we think.

“I think the main takeaway message is that the virus is pretty ubiquitous,” said first author Amanda Goldberg.

It’s unclear exactly how the animals became infected from humans, but the authors believe garbage and discarded food are the most likely sources. Two of the mice sampled at the same location on the same day during the study were found to be infected with the exact same variant of the virus, meaning they either caught it from the same human or one infected the other.

Understanding how the virus spreads in different animal populations is important to get a more detailed picture of its evolution. How does it spread from one species to another? Which wild species could serve as reservoirs for strains that are pathogenic to humans?

“We understood the critical importance of sequencing the genome of the virus infecting these species,” Finkielstein said, praising the work of the multidisciplinary team that came together for the study. One of the results, from an opossum, revealed mutations in the virus that had not been previously reported, highlighting the wealth of useful data that such studies can provide.

“The virus doesn’t care whether its host walks on two or four legs. Its primary goal is survival,” Finkielstein said, adding that “SARS-CoV-2 is not just a human problem.”

The study is published in Nature Communications.