Covid-19: Hunt for Covid’s Origin Points to China's Animal Trade

Scientists tracing the origins of the Covid-19 pandemic believe they’ve identified a possible transmission source: China’s thriving wildlife trade.

The highly anticipated findings from experts convened by the World Health Organization and the Chinese government are expected to show parallels to the spawning in 2002 of severe acute respiratory syndrome, or SARS, a bat-borne coronavirus spread by civets that killed 800 people. The path trod by SARS-CoV-2 -- as the new coronavirus is known -- before it emerged in central China in December 2019 remains a mystery, though it’s one researchers say can be solved.

In Wuhan, where the first cluster of cases occurred, scientists involved in the hunt identified four hypotheses to explain the virus’s genesis, including two that stoked controversy even as they were deemed unlikely. The idea that the virus was introduced via contaminated food or packaging is one embraced in Beijing, while the Trump administration said it may have been the result of a laboratory accident. But the most plausible theory, say experts involved in the mission, concerns China’s wildlife trade for food, furs and traditional medicine, a business worth about 520 billion yuan ($80 billion) in 2016.

Live animals susceptible to coronavirus infection were present at the Huanan food market in downtown Wuhan, the city where the first major Covid-19 outbreak was detected. It’s possible they acted as conduits for the virus, carrying it from bats -- likely the primary source -- to humans, says Peter Daszak, a zoologist who was part of the joint research effort, which saw international experts visit Wuhan earlier this year after months of stonewalling by the Chinese government.

“The main conclusion from this stage of the work -- and it’s not over yet of course -- is that the exact same pathway by which SARS emerged was alive and well for the emergence of Covid,” said Daszak, who is also president of EcoHealth Alliance, a New York-based nonprofit that works to prevent viral outbreaks around the world.

Farmed and wild-caught civets, a small, nocturnal mammal consumed in China, were blamed for spreading the SARS virus in a market in the southern province of Guangdong in 2003. Scientists later found the infection originated in horseshoe bats, a natural reservoir of coronaviruses.

The two species likely collided in markets where live animals are caged in crowded conditions, potentially allowing the bat-borne virus to adapt and amplify before it spilled over to humans, initially among workers and those handling the animals.

Scientists working on the origin hunt say a similar scenario may have played out with Covid-19. A study of the first 99 patients treated at an infectious diseases hospital in Wuhan found half were linked to the Huanan seafood market, which also reportedly sold live animals, some illegally captured in the wild and slaughtered in front of customers.

Still, questions remain about the market’s ultimate role.

Testing after it was shut down in December 2019 failed to turn up any infected animals. Contaminated surfaces were widespread, compatible with the virus being introduced via infected people or tainted animal products. Compounding the confusion, the first known Covid-19 patient developed symptoms four days before the earliest cases tied to the market.

The WHO research team found evidence that wildlife farms in southern China were supplying vendors at the Huanan market, Daszak told the U.S.’ National Public Radio. It also found a route from southern provinces such as Yunnan -- where the closest known coronavirus to SARS-CoV-2 was found in horseshoe bats in 2013 -- to Wuhan, he said on the Chatham House webinar.

“It provides a link and a pathway by which a virus could convincingly spill over from wildlife into either people or animals farmed in the region, and then shipped into a market by some means,” Daszak said. “That’s a really important clue. Those beginnings of an understanding of a pathway need to be followed up pretty rapidly.”

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