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Scientists watching The origins of the Covid-19 pandemic are believed to have identified a possible source of transmission: 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 with the 2002 reproduction of severe acute respiratory syndrome or SARS, a coronavirus transmitted by bats, spread by civets that killed 800 people. The path taken by SARS-CoV-2 – as the new coronavirus is known – before it appeared in central China in December 2019 remains a mystery, although researchers say it can be solved.
In Wuhan, where the first group of cases occurred, scientists involved in the hunt identified four hypotheses to explain the genesis of the virus, including two that sparked controversy, even though they were considered unlikely. The idea that the virus was introduced through contaminated food or packaging is one embraced in Beijing, while the Trump administration said it could 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.
Read more: Where are we looking for the origin of the coronavirus?
Live animals susceptible to coronavirus infection were present at the Huanan food market in downtown Wuhan, the city where the first major outbreak of Covid-19 was detected. It may have acted as a conduit for the virus, transporting it from bats – probably the primary source – to humans, he 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 fighting by the Chinese government.
“The main conclusion from this stage of the paper – and it is not over yet, of course – is that exactly the same way SARS appeared was alive and well for the emergence of Covid,” said Daszak, who is also president of EcoHealth Alliance, a non-profit organization in New York that works to prevent viral outbreaks around the world.
The report of the scientists, published this week after delays due to the political struggle are likely to be far from conclusive. Several studies are planned, including outside China, with the decipherment of the story of the creation of Covid-19, vital for understanding the best way to counteract its reappearance and for helps avoid similar catastrophes in the future.
China is making it difficult to solve the mystery of where Covid began
While the hunt for the origin of the virus has become political football for the world’s superpowers, Daszak says he believes the scientific process will prevail. Significant data on the origin of SARS-CoV-2 and how it appeared will be discovered in the next few years, he said during a March 10 webinar organized by Chatham House.
The spread of SARS
Farmed and caught in the wild civets, a small nocturnal mammal consumed in China, has been 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 on a market in Guangdong in 2002.
Photographer: Richard A. Brooks / AFP / Getty Images
The two species probably clashed in the markets where live animals are placed in cages crowded conditions, potentially allowing the virus transmitted by bats adapt and amplify before spilling over into people, initially among workers and animal handlers.
Scientists working on the origin hunt say that a similar scenario could have been played with Covid-19. A study of the first 99 patients treated at an infectious disease hospital in Wuhan found half were related to Huanan Seafood Market, which also it’s said sold live animals, some illegally caught in the wild and slaughtered in front of customers.
The virus may have been introduced by an infected animal that was sold on the Huanan market or elsewhere in Wuhan, said Dominic Dwyer, a Sydney microbiologist who was part of the WHO-convened team that traveled to the Chinese city. in February.
However, questions remain about the final role of the market.
Testing after it was closed in December 2019 failed to show infected animals. Contaminated surfaces were widespread, compatible with the virus introduced through infected people or contaminated animal products. Worsening the confusion, the first known patient with Covid-19 developed symptoms four days before the first market-related cases.
Review of Huanan and Wuhan’s other markets (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 circulating in the community for weeks before doctors warned it by a handful of seriously ill patients with a mysterious viral pneumonia.
The initial outbreak of coronavirus in humans has probably been followed by rapid adaptation of the virus, said Joel O. Wertheim, an associate professor of medicine at the University of California, San Diego. The virus may have been transmitted several times and they disappeared when infected individuals did not transmit the virus to anyone, Wertheim and colleagues said in a March 18 paper in the journal Science. Eventually, the virus infected someone who transmitted it to several people, who transmitted it to others, possibly in a widespread event.
Huanan Square may have been where this took place, Wertheim said in an interview. “The market may have been key to getting the virus to people.”
Current evidence suggests that the market was amplified by SARS-CoV-2 and not necessarily the birthplace, Dwyer said.
‘The perfect place’
“When you visit the market, you realize that it is a perfect place to produce an outbreak, because it is crowded, a lot of stalls, a lot of animal products, and the ventilation and drainage are a little suboptimal,” he said in -an interview. “No wonder we had an explosion there.”
The WHO research team found evidence that Wildlife farms in southern China provided vendors in the Huanan market, Daszak told US National Public Radio. He also found a route in the southern provinces, such as Yunnan – where The closest known coronavirus to SARS-CoV-2 was found in horseshoe bats in 2013 – in Wuhan, he said on the Chatham House website.
WHO team members arrive at the Chinese Center for Disease Control and Prevention in Wuhan in February.
Photographer: Hector Retamal / AFP / Getty Images
“It provides a link and a way for a virus to convincingly spread from wildlife to humans or to animals raised in the region, and then transported to a market by certain means,” Daszak said. “It simply came to our notice then. Those beginnings of understanding a path must be traced fairly quickly. ”
For decades, the Chinese government has promoted wildlife agriculture to increase rural incomes. Practice has provided a particularly valuable alternative source of meat after African swine fever appeared in 2018. The deadly outbreak has led to an unprecedented shortage of pork, researchers at the Agricultural University of South China and the University of Glasgow have said. in a study that was launched in February without a formal peer review. China usually consumes half of the world’s pork.
Squirrels, Porcupini
While the lack of pigs has strengthened the consumption of wild animals, the consumption of birds, snakes, Bamboo rats, squirrels, porcupines and other untamed animals were already popular, especially in the southern provinces, the researchers said.
They cited a survey conducted in 2004 by the China Wildlife Conservation Association, which found that 46% of urban dwellers had consumed wildlife and 2.7% were regular consumers. A January 2017 survey found that 52% of the markets they investigated were it sells wildlife, while 40% of restaurants provided wildlife food.
A large part of the trade ended just over a year ago. After President Xi Jinping warned that the consumption of wild animals is a A huge risk to public health, the Standing Committee of the National People’s Congress decided on February 24, 2020, to extend the scope of the Chinese law on wildlife protection to prohibits the consumption of almost all wild animals.
Amid international criticism of managing the early days of the pandemic, China’s official rhetoric focuses on creating doubt that the pathogen originates within its borders. But China targeted 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 route” for the coronavirus to reach Wuhan, he said. “And when the WHO report comes out … we think it’s the most likely way.”