At least 47,000 wild animals were illegally sold in markets across Wuhan before the COVID-19 pandemic, a study found, adding fuel to the fierce debate over the origins of the pandemic.
The study filled important gaps in our knowledge about the circumstances around some of the earliest known human cases of the coronavirus that emerged in the central Chinese city in late 2019. It provided the most detailed picture yet of the trade of live wild animals that could have spread the virus to people.
Researchers found that 38 mammal, reptile, and bird species were sold in four markets in Wuhan between May 2017 and November 2019. The animals included raccoon dogs, civets, and minks, which scientists previously identified as possible intermediate hosts that spread the virus from a bat to the human population.
The study, published in peer-reviewed journal Scientific Reports on June 7, was authored by researchers affiliated with China West Normal University, University of Oxford and the University of British Columbia. They happened to be conducting monthly surveys of 17 wild animal shops across Wuhan to look into potential animal sources of a pathogen unrelated to the novel coronavirus.
Scientists have yet to find the missing links between bats, the likely original host of SARS-CoV-2, and the first human cases. SARS-CoV-2 is the name of the virus that causes COVID-19.
A direct infection by bats in Wuhan is deemed unlikely because the city is far from their natural habitats, and the study said bats were not sold in the Wuhan markets it surveyed, including the Huanan seafood market.
A WHO-China joint mission to Wuhan earlier this year said the coronavirus likely jumped to humans through an intermediate host in a natural spillover event, although the head of WHO said all hypotheses remained on the table.
Some virologists have cited the study as further evidence that animals capable of carrying SARS-CoV-2 were actively traded in the city’s markets in poor hygiene conditions and could have passed the virus on to people and triggered the pandemic that has killed more than 3.7 million people worldwide.
Others, including those who believe that the virus spilled from a lab in Wuhan, have argued that the paper ruled out pangolins as an intermediate host of the virus, since the researchers did not find those animals at the markets.
Angela Rasmussen, a virologist with the University of Saskatchewan in Canada, who was not involved with the study, said the research strengthened the possibility of the natural emergence of SARS-CoV-2 by showing that some animals susceptible to the novel coronavirus were present in Wuhan.
“It puts the animals in Wuhan and makes a compelling hypothesis,” Rasmussen told VICE World News, although she said it was “not proof.”
“To give proof, we would have to actually sequence and isolate a virus that is very much like SARS-CoV-2 from one of these animals.”
Previously, the WHO-China joint report identified only snakes, salamanders, and crocodiles as being sold as live animals in the Huanan seafood market in Wuhan, which 28 percent of the first confirmed COVID-19 patients had exposure to. The news media previously reported that plenty of live animals were sold in the market, but the WHO-China joint mission called those reports unverified. Instead, it cited local authorities’ assertion that no illegal trade in wildlife took place in the market, a claim that the newly-published study suggests was false.
Rasmussen said the next step should be tracing the sources of the animals, sampling the wild animals that have been transported throughout China, and screening them for related viruses.
“Regardless of the circumstances in which a novel virus emerges, we don’t always figure out where it came from right away, and sometimes we don’t find out ever,” she said.
The study also found significant hygiene and animal welfare problems in markets in Wuhan. Some mammals suffered wounds from gunshots or traps, suggesting they were harvested illegally, according to the study. Seven of the 17 shops surveyed were located in the Huanan market.
“Almost all animals were sold alive, caged, stacked and in poor condition,” the study wrote. “Most stores offered butchering services, done on site, with considerable implications for food hygiene and animal welfare.”
The availability of the animals, many of them protected species, also pointed at lags in China’s law enforcement on wildlife trade before the pandemic, even after the trade was implicated in the SARS outbreak in the early 2000s, which was also caused by a coronavirus.
The Chinese government has toughened a crackdown on wildlife trade and consumption since the start of the COVID-19 pandemic.
But some scientists say the list of wild animals sold in Wuhan offers little help in tracing the origins of the coronavirus.
Roger Frutos, an expert on emerging infectious diseases with the University of Montpellier in France, said the coronavirus had likely been circulating and evolving in the human population long before the first COVID-19 outbreak was recorded in Wuhan.
“Wuhan is the place where the disease was recognized, it is not necessarily the place where the contamination, or the first infection, took place,” Frutos, who was not involved in the study, told VICE World News.
“The virus could have been brought in by somebody else from China or from another country,” he said.
Previously, the WHO-China report said it could not draw a conclusion on the role of the Huanan seafood market in the early epidemic, noting that 45 percent of the known early cases had no connection to it. It said mild and asymptomatic cases that were undetected could have linked those cases to Huanan and other markets. The report recommended testing blood samples previously collected in Wuhan and outside China for potential signs of transmission of the virus before the earliest known cases.
Some scientists have called for more thorough investigations into the possibility that the COVID-19 pandemic had resulted from a lab spillover, a scenario called “extremely unlikely” by the WHO-China mission. In May, 18 scientists published a letter on Science calling on hypotheses about both natural and laboratory spillovers to be taken seriously.
Later that month, U.S. President Joe Biden ordered intelligence agencies to produce a report on COVID-19’s origins within 90 days, to be focused on whether the virus came from a natural spillover or a lab accident, citing conflicting assessments among officials in the U.S. intelligence community.
Frutos, however, said looking for the animal origin of the pandemic could be a futile attempt. More resources, he said, should be devoted to investigating the societal factors, such as gatherings or political meetings, that turned COVID-19 from a local outbreak to a global pandemic.
The Chinese government has been widely criticized for trying to cover up early signs of the outbreak in Wuhan and allowing large gatherings to proceed in the weeks after mysterious pneumonia cases were reported in the city.
“What we really have to do is to focus on how the virus can move from one that got a few people infected to one that got a lot of people infected.”