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Scientists who believe the origins of the Covid-19 pandemic have identified a possible source of transmission: China’s thriving wildlife trade.
The long-awaited findings of experts convened by the World Health Organization and the Chinese government are expected to show parallels to the 2002 release of severe acute respiratory syndrome, or SARS, a bat-borne coronavirus spread by civets that killed 800 people. The path that SARS-CoV-2 walked – as the new coronavirus is known – before emerging in central China in December 2019 remains a mystery, although it can be solved, according to researchers.
In Wuhan, where the first cluster of cases occurred, scientists involved in the hunt identified four hypotheses to explain the origin of the virus, including two that sparked controversy even if deemed unlikely. The idea that the virus was introduced through contaminated food or packaging is being embraced in Beijing, while the Trump administration said it may have resulted from a laboratory accident. But the most plausible theory, experts involved in the mission say, concerns China’s wildlife trade for food, fur and traditional medicine, a company worth it 520 billion yuan ($ 80 billion) in 2016.
Read more: Where do we hunt for the origin of the coronavirus?
Live animals susceptible to coronavirus contamination were present at Huanan’s food market in central Wuhan, the city where the first major Covid-19 outbreak was detected. It’s possible they acted as channels 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, who saw international experts visit Wuhan earlier this year after months of stonewalling by the Chinese government.
“The main conclusion from this phase of the work – and of course it’s not over – is that the very same path through which SARS emerged was alive and kicking before Covid’s rise,” said Daszak, who is also chairman of EcoHealth Alliance, a New York-based nonprofit that works to prevent viral outbreaks around the world.
The scientists’ report, scheduled for release this week after delays due to political disagreement are likely to be far from convincing. More studies are planned, including outside of China, to decipher the Covid-19 creation story, vital to understanding how best to counter its resurgence, and to help prevent similar disasters in the future.
China is making it more difficult to solve the mystery of where Covid started
While the hunt for the virus’s origins has become political football for the world’s great powers, Daszak says he thinks the scientific process will prevail. Significant data on where SARS-CoV-2 came from and how it originated will be brought to light in the coming years, he said during a webinar hosted by Chatham House.
SARS spread
Farmed and caught in the wild civets, a small, nocturnal mammal consumed in China, were blamed for spreading the SARS virus in a market in southern Guangdong province in 2003. Scientists later discovered that the infection originated in horseshoe bats, a natural reservoir of coronaviruses.
A civet at a market in Guangdong in 2002.
Photographer: Richard A. Brooks / AFP / Getty Images
The two types likely collided in markets where live animals are locked up crowded conditions, which may allow the bat-borne virus Adjust and strengthen before it passed to people, initially under workers and those who handle the animals.
Scientists working on the origin hunt say a similar scenario may have happened with Covid-19. A study of the first 99 patients treated at an infectious disease hospital in Wuhan found half was linked to the Huanan fish market, which too Reportedly sold live animals, some illegally caught in the wild and butchered in front of customers.
It’s possible the virus was introduced via an infected animal sold in the Huanan market or elsewhere in Wuhan, said Dominic Dwyer, a microbiologist in Sydney who was part of the WHO convened team that traveled to China in February. city.
Still, questions remain about the ultimate role of the market.
Testing after it shut down in December 2019 did not reveal any infected animals. Contaminated surfaces were widespread, compatible with the virus introduced from infected humans or contaminated animal products. To add to the confusion, the first known Covid-19 patient developed symptoms four days before the earliest cases hit the market.
Revisiting the other markets of Huanan and Wuhan (video)
An analysis of SARS-CoV-2 samples collected in mid-December found subtle genetic differences between them. The variation indicates that the virus may have been sneaking around the community for weeks before doctors were made aware of it via a handful of critically ill patients with a mysterious viral pneumonia.
The coronavirus’ original transfer to a human was likely followed by a rapid adaptation of the virus, said Joel O. Wertheim, associate professor of medicine at the University of California, San Diego. It is possible that the virus has been transmitted multiple times and died when infected individuals didn’t transmit the virus to anyone, Wertheim and colleagues said in an article published March 18 in the journal Science. Ultimately, the virus infected someone who passed it on to several people, who also passed it on to others, possibly in a super-spreading event.
The Huanan market may have been where that took place, Wertheim said in an interview. “The market may have been the key to the virus settling in humans.”
Current evidence suggests the market is where SARS-CoV-2 was boosted, and not necessarily the hometown, Dwyer said.
‘Perfect place’
“When you visit the market, you realize it’s a perfect place for an outbreak because it’s packed, lots of stalls, lots of animal products, and ventilation and drainage are a bit sub-optimal,” he said in an interview. “It’s not surprising we had an explosion there.”
The WHO research team found that evidence wildlife farms in southern China provided suppliers to the Huanan market, Daszak told National Public Radio. It also found a route from southern provinces such as Yunnan – where the The most famous coronavirus for SARS-CoV-2 was found in 2013 in horseshoe bats – for Wuhan, he said on the Chatham House webinar.
Members of the WHO team arrive at the China Center for Disease Control and Prevention in Wuhan in February.
Photographer: Hector Retamal / AFP / Getty Images
“It provides a link and a path by which a virus can convincingly spill over from wildlife to humans or animals grown in the region and then somehow be shipped to a market,” said Daszak. That is a very important indication. That beginnings of understanding a path must be followed quite quickly. “
In front of For decades, the government of China has promoted wildlife farming to bolster rural incomes. The practice subsequently produced a particularly valuable alternative meat source African swine fever started in 2018. The deadly outbreak resulted in an unprecedented shortage of pork, according to researchers from South China Agricultural University and University of Glasgow. in a study released in February without a formal peer review. China typically consumes half of the world’s pork.
Squirrels, porcupines
While the shortage of pork reduces the consumption of wild animals, the food of birds, snakes, bamboo rats, squirrels, porcupines and other non-domesticated animals were already popular, especially in southern provinces, the researchers said.
They cited a 2004 study by the China Wildlife Conservation Association that found that 46% of city residents had consumed wildlife and 2.7% were regular consumers. A January 2017 survey found that 52% of the markets surveyed were wildlife trade, while 40% of the restaurants catered to wildlife.
Lots of the trading is said to have ended a little over a year ago. After President Xi Jinping warned that wildlife consumption was a enormous risk to public health, the Standing Committee of the National People’s Congress decided on February 24, 2020 to extend the scope of China’s wildlife protection law to prohibit the consumption of almost all wild animals.
Amid international criticism of the handling of the pandemic’s early days, China’s official rhetoric aims to cast doubt that the pathogen originated within its borders. But China focused on the wildlife trade a year ago for a reason, Daszak told NPR.
“The reason was that in February 2020 they thought this was the most likely way” for the coronavirus to reach Wuhan, he said. “And if the WHO report comes out … we think this is also the most likely route.”