Tue. Dec 7th, 2021


“Punishment for the perpetrators can be severe,” said Zhao Xiaomin, a Chinese wildlife trade policy expert at China West Normal University in Nanchang. Those who trade in protected species could face up to 15 years in prison, and trafficking in large quantities inside or outside China could result in life imprisonment.

But law enforcement was weak. Several researchers told the MIT Technology Review that it was “an open secret” that the illegal wildlife trade was rampant in China.

Indeed, Zhou and his colleagues managed A survey Between 2017 and 2019, about 48,000 wild animals of 38 species were sold in four markets in Wuhan, including Huanan, almost all of which were sold alive, in cages and in thin, unhealthy conditions suitable for virus transmission. Animals হয় either wild-caught or cultivated non-domesticated species রয়েছে include species sensitive to both SARS-CoV-1 and SARS-CoV-2, such as civets, mink, badgers, and raccoon dogs.

That study, published in June Scientific reportAll of the wildlife businesses surveyed by researchers are illegal. Many vendors sell protected species; No one posted the required credentials that indicated the origin of the animals or that they were disease free.

This means that as soon as Huanan is involved in the Covid-19 case, vendors selling live mammals will, perhaps illegally, flee to avoid imprisonment, while law enforcement agencies are less likely to acknowledge the existence of such activity in the first place. Hanez of Harvard said it was “surprising” that Chinese authorities did not find any leads in the sale of live animals in the Huanan market.

Restrictions on wildlife trade were minimal after SARS, which gave scientists almost unlimited access to animals and traders in Guangdong’s wet market – but not enough to help them find the source of SARS. When they quickly enter the virus in civets, badgers and raccoon dogs More than 99% identical with SARS-CoV-1, Subsequent investigations did not show widespread prevalence of the virus in wild or cultivated conditions. That is an influential aspect Civets got the virus while trading, Probably from bats bought and sold at the same time.

Now, 18 years later, the situation is remarkably similar. There seems to be SARS-CoV-2 is not widespread in animals. None of the 80,000 or more samples tested by the Chinese team of the World Health Organization to investigate the origin of the epidemic contained the virus – the main suspects being pangolins, civets, badgers and bamboo rats.

Nevertheless, many scientists still strongly believe that wet markets played a significant role in the Covid-19 trigger. Although all eyes are on Yunnan and other parts of Southeast Asia as a possible source of the epidemic, Hanez says “this is not a windmill madness” to suggest that Uhan may be the province of Hubei where SARS-CoV-2 originated naturally.

In fact, scientists at the Wuhan Institute of Virology have found Coronavirus like SARS in bats in Hubei. Although they have not systematically tested farmed animals for coronavirus infection across the province, A little known study Conducted after SARS, they found that all seven civets they tested on a farm in the province in 2004 were infected by SARS-CoV-1 relatives. Several research teams in China and the United States are trying to determine where the virus came from in animals, whether coronavirus infection is more common among civets than previously thought, and how it may affect our understanding of the source of Covid-19.

Constant spillover

But without evidence of coronavirus-infected animals being more than 99% identical to SARS-CoV-2, some scientists continue to argue against natural sources.

One such critic is Alina Chan, a molecular biologist at the Broad Institute of MIT and Harvard (this publication is owned by MIT, but editorially independent of it). In the central question, he said, a Recent webinars hosted by Science MagazineHow did the virus get there from caves more than a thousand miles away in China or other parts of Southeast Asia? “Scientists in Uhan have a very strong canal where they have landed in these places [knew] They will find the SARS virus and bring it thousands of miles to Wuhan, ”he said. There is no evidence of such a route for wildlife trade, he added.

Linfa Wang, director of the Emerging Infectious Diseases Program at Duke-National University of Singapore, says the lack of such transparency also plagues the source of SARS. The cave that gave birth to the closest bat relative of SARS-CoV-1 is about 1,000 miles from Guangdong market where the first SARS case first appeared – the distance between Wuhan and the place where one of the closest bat relatives of SARS-CoV-2 was discovered. Done.

And it is increasingly clear that people in close contact with wildlife are more likely to be infected with the coronavirus than previously thought.

“[Huanan] Based on what we know now, there is a lot more potential than other situations. “

Michael Orobe

Studies show that up to 4% Those who live near bats And Work closely with wildlife South China has been infected with a deadly animal-borne virus, including coronavirus. A Laotian and French team, which discovered Close relative of SARS-CoV-2, Found that One in five Laotian bat handlers had antibodies against coronavirus.

Researchers say that most of these spillover infections go away on their own. In a study published in science in April, Worobey and his colleagues show in computer simulations that an urban environment is critical to start a large-scale epidemic of SARS-CoV-2 spillover – without it, it will die very quickly.

“It’s hundreds, not thousands, many times more,” said a wildlife trader who came in contact with a SARS-CoV-2 ancestor – from a bat or other animal species – who brought the virus to Huanan, a researcher who went to collect samples from bats. The pathogen was brought back to Wuhan and then brought to Huanan, Wang said.

Orobe agrees. Based on many lines of evidence, he is now convinced that the epidemic’s connection to the Huanan market is not real, but is where a SARS-CoV-2 ancestor jumped from an animal to a human. “Based on what we know now, this is far more likely than any other situation,” he said.

Preliminary results from ongoing work by his group and others will help strengthen the case, he added: “They all point in the same direction.”

Editor’s note: This story has been edited to clarify the identity of the person who was previously believed to be the first diagnosed case of Covid-19.

Reporting for this article was supported by a grant from the Pulitzer Center.



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