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• Posted September 19, 2024

New Data Supports Animal Market Origins for COVID Pandemic

The Hunan Seafood Wholesale wet market in Wuhan, China, has long been considered the most likely source of the coronavirus that caused the COVID-19 pandemic.

That theory is now supported by a new study analyzing more than 800 samples collected in and around the market in January 2020 as the pandemic began.

Those samples show that animal species known to carry the COVID coronavirus were present in the market, according to results published Sept. 18 in the journal Cell.

“This paper adds another layer to the accumulating evidence that all points to the same scenario: that infected animals were introduced into the market in mid- to late November 2019, which sparked the pandemic,” said study co-author Kristian Andersen, director of infectious disease genomics with Scripps Research.

The common raccoon dog, a series susceptible to SARS-CoV, is closely linked to market wildlife stalls that contained SARS-CoV-2, researchers found.

Genetic material from other species like masked palm civets, the Hoary bamboo rat and the Malayan porcupine were also associated with COVID, results show.

“These are the same sorts of animals that we know facilitated the original SARS coronavirus jumping into humans in 2002,” said study co-author Michael Worobey, head of ecology and evolutionary biology with the University of Arizona.

He said the scenario in late 2019 in Wuhan was a set-up for trouble.

“This is the most risky thing we can do -- take wild animals that are teeming with viruses and then play with fire by bringing them into contact with humans living in the heart of big cities, whose population densities make it easy for these viruses to take hold,” Worobey said in a journal news release.

China’s version of the Centers for Disease Control and Prevention went into the wet market just hours after it was shut down. Investigators swabbed floors, walls and stall surfaces around the market, gathering hundreds of samples.

The Chinese CDC team returned days later to focus on surfaces in stalls selling wildlife, such as cages and carts used to move animals. They also collected samples from drains and sewers.

“Many of the key animal species had been cleared out before the Chinese CDC teams arrived, so we can’t have direct proof that the animals were infected,” noted study co-author Florence Debarre with the French National Center for Scientific Research.

“We are seeing the DNA and RNA ghosts of these animals in the environmental samples, and some are in stalls where SARS-CoV-2 was found, too,” Debarre added. “This is what you would expect under a scenario in which there were infected animals in the market.”

For the new study, an international research team performed genetic sequencing of the samples, to track the presence of SARS-CoV-2 and to create a list of the wildlife species at the market from which COVID likely jumped into humans.

Evolutionary analysis of the earliest COVID pandemic strains implies that there were very few, if any, humans infected prior to the market outbreak. This is consistent with other events where animal viruses made the leap into humans, researchers said.

“In this paper, we show that the sequences linked to the market are consistent with a market emergence,” Debarre said. “The main diversity of SARS-CoV-2 was in the market from the very beginning.”

Figuring out the origins of the pandemic continues to be important, researchers argue, given the ongoing threat from animal-borne pathogens like avian flu.

“There has been a lot of disinformation and misinformation about where SARS-CoV-2 originated,” Worobey said. “The reason it’s so important to find out is that this affects national security and public health, not just in the United States but around the world. And the truth is, since the pandemic started more than four years ago, although there has been an increased focus on lab safety, not much has been done to decrease the chance of a zoonotic scenario like this happening again.”

More information

The National Intelligence Council has more on the origins of the pandemic.

SOURCE: Cell Press, news release, Sept. 19, 2024