In China and Southeast Asia, hundreds of thousands of people can be infected annually by animals carrying the coronavirus that causes COVID-19, according to a study emphasizing the ongoing pandemic risk from spillover incidents.
On average, 400,000 such infections occur annually, most of which go unrecognized because they cause mild or no symptoms, researchers from the EcoHealth Alliance and the Duke-NUS Medical School in Singapore said in a study released Thursday ahead of peer review. and are not easily transmitted between people. Publication. Nevertheless, each spillover represents an opportunity for viral adaptation that can lead to a COVID-like outbreak.
The question of where and how the virus that causes Covid has emerged has become particularly controversial, with some leaders attributing a hypothetical leak from a laboratory in Wuhan, China that studies pathogens. The research, supported by the US National Institute of Allergy and Infectious Diseases, is based on evidence that bats are the main host-animals for viruses such as SARS-CoV-2 and that people living near their habitat are particularly vulnerable.
“This is perhaps the first attempt to estimate how often people are infected with SARS-related coronaviruses from bats,” said Edward Holmes, an evolutionary biologist at the University of Sydney. He said humans are constantly exposed to bat coronaviruses. “Given the right set of circumstances, one of these could eventually lead to an outbreak of disease.”
About two dozen bat species that can be infected with coronaviruses inhabit a region in Asia more than six times the size of Texas, southern China and parts of Myanmar, Laos, Vietnam and Indonesia most at risk for spillover. considered filled. Peter Daszak of the New York-based EcoHealth Alliance and his colleagues used bat distribution modeling and ecological and epidemiological data to estimate the risk of exposure to coronaviruses related to SARS, and non-bat to humans in China, South Asia and China. Estimated infection rate. Southeast Asia.
The researchers said the approach provides a proof of concept for systematic risk assessment of wildlife-to-human spillover events and a strategy to identify key geographic areas that can be prioritized for targeted monitoring of wildlife, livestock and humans. .
He said in the study, “Given the challenges of identifying the origin of COVID-19 and the routes by which SARS-CoV-2 reached people, this approach may also aid efforts to identify geographic locations where , where the spillover first occurred.”
Nearly two years after COVID began infecting people in the central Chinese city of Wuhan, scientists have yet to determine the origin of the pandemic. Daszak, who supports the wildlife source theory, has been criticized for collaborating on National Health-funded research on laboratory studies at the Wuhan Institute of Virology, which some scientists say led to the creation of an ancestral virus. could be the reason.
No evidence has emerged to support the lab-leaked theory. Last month, the US intelligence community ruled out the possibility that SARS-CoV-2 was developed by China as a biological weapon, but no consensus was reached on its origin.
Daszak’s study estimates that 50,000 bat-to-human spillover incidents occur annually in Southeast Asia, adding that the number could run into the millions.
“The risk of animals being exposed to the virus in nature is “far greater than any potential exposure in the laboratory,” Holmes said. The risk of exposure is even greater when you factor in all possible ‘intermediate’ animal species.”
According to research, these include mink, civet, raccoon dog and other mammals, which are commonly farmed and traded in Asia for food and fur. It said that in 2016 alone, wildlife farming employed 14 million people in China – a $77 billion industry annually.
In Asia, about 478 million people live in an area inhabited by bats carrying the coronavirus, which includes most of Laos, Cambodia, Thailand, Vietnam, Nepal, Bhutan, Peninsular Malaysia, Myanmar, southeast China and the western islands of Indonesia . said.