Humans are spilling the COVID-19 virus back into wildlife! Study finds widespread infection in backyard animals

Everything is connected. Nature itself thrives on an intricate web of interdependence, with every element—including human beings—complexly intertwined. Now, this fundamental fact is being further reinforced by new findings on COVID-19.

The SARS-CoV-2 virus initially jumped from animals to humans, triggering a pandemic on the global stage. As cases multiplied across populations worldwide, humans have ended up spilling the virus back into the wildlife, leading to new outbreaks among various animal species.

Genetic analysis of wild animals has revealed not only the presence of SARS-CoV-2, but also the emergence of unique viral mutations. These mutations show a close relationship to the variants circulating among humans, illustrating the ongoing exchange between our species and wildlife.
Nature’s COVID-19 cycle: From wildlife to humans and back again
The study by Virginia Tech involved analysing 798 nasal and oral swabs from animals trapped in the field or treated at wildlife rehabilitation centres across Virginia, US, along with 126 blood samples from six species. This research, recently published in Nature Communications, aimed to track the virus’s presence in animals from both urban and remote areas.

The findings are revealing: the virus was detected in deer mice, Virginia opossums, raccoons, groundhogs, Eastern cottontail rabbits and Eastern red bats. Notably, one opossum exhibited viral mutations not previously reported, which could influence human health and immune responses. Exposure rates varied by species, ranging from 40% to 60%.

The study also noted a peculiar finding: two mice at the same site on the same day carried identical viral variants, suggesting possible direct transmission between them, or from a common human source!

The highest rates of virus exposure were observed in animals near hiking trails and high-traffic areas, indicating that human activity is a significant factor in the spread to wildlife. The exact transmission pathways remain unclear, with possibilities including wastewater or discarded food.

However, researchers emphasise that while the virus is spreading to wildlife, there is no evidence of reverse transmission from animals to humans.
Carla Finkielstein, a professor of biological sciences, describes the virus' behaviour as akin to “a hitchhiker switching rides to a new, more suitable host”. With humans largely protected by vaccines, the virus—with the sole goal of spreading and surviving—is adapting and mutating to thrive in animal hosts.

Although this study is limited to Virginia, the species affected are found throughout North America. This means the findings may also be applicable to other countries and continents to a certain extent. Moreover, this research doesn’t just highlight the novel mutations in SARS-CoV-2, but also underscores the broad host range of the virus. Therefore, researchers stress the urgent need for extensive surveillance to monitor the virus' impact on wildlife and its potential implications for vaccine development.