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Scientists following the The origins of the Covid-19 pandemic are believed to have identified a possible source of transmission: China’s thriving wildlife trade.
The long-awaited results of experts convened by the World Health Organization and the Chinese government are expected to draw parallels with the introduction in 2002 of severe acute respiratory syndrome or SARS, a coronavirus transmitted by bats. civets that killed 800 people. The path taken by SARS-CoV-2, as the new coronavirus is known, before it emerged in central China in December 2019 remains a mystery, although researchers say it can be solved.
In Wuhan, where the first cluster of cases occurred, scientists involved in the hunt identified four hypotheses to explain the genesis of the virus, including two that sparked controversy, even as they were considered unlikely. The idea that the virus was introduced through contaminated food or packaging is an idea that was adopted in Beijing, while the Trump administration said it could have been the result of a laboratory accident. But the most plausible theory, experts involved in the mission say, concerns China’s wildlife trade for food, skins and traditional products. medicine, a worthwhile business 520 billion yuan ($ 80 billion) in 2016.
Read more: Where do we look for the origin of the coronavirus?
Live animals susceptible to coronavirus infection were present at the Huanan food market in central Wuhan, the city where the first major outbreak of Covid-19 was detected. They may have acted as conduits for the virus, carrying it from bats (probably the main source) to humans, he says. Peter Daszak, a zoologist who was part of the joint research effort, who saw how international experts visited Wuhan earlier this year after months of walling the Chinese government.
“The main conclusion of this stage of the work (and it’s not over yet, of course) is that the very pathway by which SARS arose was alive and well for the emergence of Covid,” said Daszak, who he is also president of EcoHealth Alliance, a New York-based nonprofit organization that works to prevent viral outbreaks around the world.
The scientists’ report, published this week later delays due to the political dispute, it is likely not even very conclusive. More studies are planned, including outside China, with the decipherment of Covid-19’s creation history, vital to understanding the best way to thwart its resurgence and to help prevent similar catastrophes in the future.
China makes it harder to solve the mystery of where Covid started
Although the search for the source of the virus has become political football for the world superpowers, Daszak says he believes the scientific process will prevail. Over the next few years, significant data will be uncovered as to where SARS-CoV-2 arose and how it arose, he said during a March 10 webinar organized by Chatham House.
SARS dissemination
Of cultivation and wild capture civets, a small nocturnal mammal consumed in China, were blamed for spreading the The SARS virus a Guangdong Province market in 2003. Scientists later found that the infection originated in horseshoe bats, a natural coronavirus reservoir.
A civet in a Guangdong market in 2002.
Photographer: Richard A. Brooks / AFP / Getty Images
The two species probably collided in markets where live animals are caged crowding conditions, which can allow the virus to be transmitted by bats adapt and amplify before it spreads to humans, initially between animal workers and handlers.
Scientists working on the origin search say a similar scenario may have been played out with Covid-19. A study of the first 99 patients treated at an infectious disease hospital in Wuhan was found half were related to Huanan fish and seafood market, which too as supposed he sold live animals, some illegally captured in the wild and sacrificed in front of customers.
It is possible that the virus was introduced through an infected animal that was sold at the Huanan market or elsewhere in Wuhan, said Dominic Dwyer, a Sydney microbiologist who was part of the team convened by the WHO traveled to the Chinese city in February.
However, questions remain about the final role of the market.
Tests after it closed in December 2019 could not show any infected animals. Contaminated surfaces were widely compatible with the virus that was introduced through infected people or contaminated animal products. Grouping the confusion, the first known patient of Covid-19 developed symptoms four days before the first market-related cases.
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 circulated surreptitiously for weeks in the community before doctors were alerted by a handful of severe patients with viral pneumonia.
Joel O. Wertheim, an associate professor of medicine at the University of California, San Diego, said the original coronavirus discharge to a human was probably followed by a rapid adaptation of the virus. The virus may have been transmitted several times became extinct when infected individuals did not transmit the virus to anyone, Wertheim and colleagues said in a paper published March 18 in the journal Science. Eventually, the virus infected someone who passed it on to several people, who also transmitted it to others, possibly in a widespread event.
The Huanan market may have been where it came from, Wertheim said in an interview. “The market may have been key to the virus consolidating in humans.”
Current evidence suggests that the market is where SARS-CoV-2 was amplified and not necessarily its birthplace, Dwyer said.
“Perfect place”
“When you visit the market, you realize it’s a perfect place for an outbreak to occur because it’s full of people, a lot of stalls, a lot of pet products and the ventilation and drainage are a little bit optimal,” he said in an interview. . “It’s not uncommon for us to have a blast out there.”
The WHO research team found evidence that southern China’s wildlife farms supplied suppliers to the Huanan market, Daszak told U.S. National Public Radio. He also found a route from southern provinces such as Yunnan – where the Yunnan is located The closest known coronavirus to SARS-CoV-2 was found in horseshoe bats in 2013 in Wuhan, he told the Chatham House webinar.
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 route by which a virus could convincingly spill from wildlife to people or animals in the region, and then it was sent to the market by some means,” Daszak said. “This is a really important clue. We need to follow these beginnings of an understanding of a path very quickly.
To For decades, the Chinese government promoted wildlife farming to boost rural incomes. Practice provided an especially valuable alternative source of meat afterwards The African swine fever arose in 2018. The deadly outbreak resulted in an unprecedented shortage of pork, researchers at the Agricultural University of Southern China and the University of Glasgow said. in a study published in February without a formal peer review. Typically, China consumes half of the world’s pork.
Squirrels, Porcupines
While the shortage of pork reinforced the consumption of wildlife, eating birds, snakes, bamboo rats, squirrels, porcupines and other non-domesticated 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 residents had consumed wildlife and 2.7% were regular consumers. A January 2017 survey found that 52% of the markets they surveyed were wildlife trader, while 40% of restaurants provided wildlife dishes.
Much of the the trade supposedly ended just over a year ago. After President Xi Jinping warned that wildlife consumption posed a problem An immense risk to public health, on February 24, 2020, the Standing Committee of the National People’s Congress decided to expand the scope of China’s wildlife protection law. ban the consumption of almost all wild animals.
Amid international criticism of its management of the early days of the pandemic, China’s official rhetoric focuses on raising doubts that the pathogen originated on its borders. But China turned to wildlife trade a year ago for a reason, Daszak told NPR.
“The reason was that in February 2020, they believed 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 also the most likely route.”