Thousands of wild animals were sold in markets in the Chinese city of Wuhan before the Covid-19 outbreak, new research shows.
The study by British and Chinese researchers sheds light on the city’s active pet trade, which has long been seen as a potential source of the outbreak.
In the most detailed record of wildlife sales to date, scientists estimate that more than 47,000 wild animals were sold in city markets in the two and a half years before the onset of the disease.
During monthly on-site visits to 17 stores selling wildlife in four Wuhan markets between May 2017 and November 2019, researchers documented the sale of 38 species.
These included mammals such as civets, mink and raccoon dogs, which are known to be susceptible to coronaviruses, as well as squirrels, badgers, foxes and hedgehogs, as well as birds and reptiles.
However, they found no evidence that bats or pangolins – believed to be two possible sources of coronavirus transmission – had been on sale in the markets.
Seven of the vendors monitored were at the Huanan Seafood Wholesale Market, which was linked to a number of the first known cases of Covid-19 in late 2019.
Some 1,100 individual animals passed through the city’s markets on average each month, in a trade that researchers describe as both ripe for the spread of the disease and “fundamentally illegal.”
“Almost all the animals were sold alive, caged, stacked and in poor condition. Most stores offered on-site butchery services with significant implications for food hygiene and animal welfare, ”said researchers from China West Normal University and Oxford University. , who received their data directly from booth owners as part of a tick surveillance study. – transmitted disease.
The full data set, which ends just one month before the detection of the Covid-19 outbreak in Wuhan, goes far beyond information released following a visit to the city by a led team by the World Health Organization earlier this year.
A member of the WHO team, veterinarian David Hayman, said research confirmed live wild mammals were on sale in Wuhan – something the team suspected but could not verify.
It also provided clear evidence that several species known to be susceptible to coronaviruses linked to Severe Acute Respiratory Syndrome (SARS) were “routinely brought to market,” said Hayman, who is co-director of the OIE Collaborating Center. in veterinary medicine. Epidemiology and Public Health at Massey University in New Zealand.
“The data provides more support to investigate whether these potential intermediate hosts have been infected and have provided pathways from regions where evidence suggests more Sars-related coronaviruses persist in nature, such as other parts of China and from Southeast Asia, to Wuhan during the winter, ”he said. noted.
The origins of the coronavirus that causes Covid-19 remain unknown, and scientists and governments have called for further investigation into whether the virus came from a natural source or from a laboratory leak – a theory China has denied to many times.
Trade in wildlife has been identified as a possible route of transmission of the virus, which is thought to originate in bats.
Many of the first known cases, but not all, were related to the Huanan market, and subsequent analysis found that more than half of the first known cases in December 2019 were on display at this market or other markets in the city. .
But no link has been found between the animals for sale in the market and the virus.
Chinese officials said only frozen wild animals were found in the Huanan market and tested after it closed on January 1, 2020.
The WHO team’s report, based on information from Chinese authorities, only indicated that snakes, crocodiles and salamanders – which are less likely to have been infected with coronaviruses – were being sold alive on the market. market at the end of December 2019.
“It is important [to know] that there are species of mammals alive and sold in the markets of Wuhan immediately before the recognition of the appearance of Covid-19 which are susceptible to coronaviruses of the Sars, Sars-1 or Sars-CoV-2 type ”, declared Daniel Lucey, infectious disease specialist at Georgetown University Medical Center in the United States.
“This is important missing data… and it raises in my mind what other data exists that has not been made public,” he said.
Zhou Zhao-min, one of the co-authors of the article, said the data could not be shared during the review process. The research was originally submitted in February last year, but was rejected by several international journals before being submitted to Scientific Reports in October, he said.
“I hope these data could be useful in tracing the origins of Sars-CoV-2 [the coronavirus that causes Covid-19]. For example, mink was for sale in markets, while Sars-CoV-2 has been reported in mink farms in Europe and North America, ”Zhou said, adding that the document“ also highlights wildlife management shortages ”.
In the article, the authors directly question a claim in the WHO report that no illegal wildlife sales were identified in the Huanan market, noting that it would be “impossible” to take this. decision due to lack of regulation.
According to the data, around 30% of the mammals sold were clearly captured from the wild.
Notably, the researchers also said they found no evidence of pangolins – once believed to be an intermediate host animal – sold in markets, “corroborating that pangolins are unlikely to be involved as spillover hosts. “. There was also no evidence that live bats were sold in the markets.
Many of the mammalian species on the list were those that had been tested in captivity for coronaviruses by researchers in Hubei province after the outbreak, according to data from the WHO report.
When asked if the latest data would be taken into account, a WHO spokesperson said that a technical team was preparing a proposal for the next studies to be carried out based on a review of the mission report. .
Yanzhong Huang, senior researcher in global health at the Council on Foreign Relations in New York, said the latest research pointed out that work under the auspices of the WHO mission was “currently not in depth”.
“They haven’t exhausted their research, which suggests that more work needs to be done in China,” he said.
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