Corona pandemic

New evidence: Animal market in Wuhan was the origin

The coronavirus pandemic most likely started at this wild animal market in the Chinese metropolis of Wuhan.

(Bild: AFP/Hector Retamal)

A new study confirms the suspicion that the coronavirus pandemic most likely originated from a wild animal market in the Chinese metropolis of Wuhan. According to the study, samples contaminated with SARS-CoV-2 accumulated around a market stall that sold civet cats and raccoon dogs.

Both animal species were already carriers of the SARS pandemic in 2002/2003 and are also suspected to be intermediate hosts for SARS-CoV-2. At that time, almost 800 people died in over 8,000 cases worldwide. The main countries affected were China, Taiwan, Vietnam, Singapore and Canada (Toronto).

Severe acute respiratory syndrome (SARS) is an infectious disease caused by the SARS coronavirus (SARS-CoV) that presents with the clinical picture of atypical pneumonia. The virus is mainly transmitted from person to person via the inhalation of infectious droplets through contact with sick people.

Coronaviruses similar to the SARS virus have been detected in wild Chinese small mammals - such as raccoon dogs (pictured below) and civets - so it can be assumed that the infection primarily originated from these animals.

(Bild: AFP/Greg Baker)

A new study provides a short list of the wild animal species that were present in the market from which SARS-CoV-2, the pathogen responsible for the Covid-19 pandemic, is highly likely to have emerged at the end of 2019.

More than 800 samples analyzed
The study published in the journal "Cell" is based on an analysis of genetic data published by the Chinese Center for Disease Control and Prevention (CDC). They come from more than 800 samples collected in and around the Huanan Seafood Market in Wuhan from January 1, 2020, as well as from viral genomes of the first Covid-19 patients.

For the study, a team led by Michael Worobey from the University of Arizona analyzed DNA and RNA from animal stalls, surfaces and sewage gutters for both the presence of SARS-CoV-2 and the exact genetic lineage of the coronavirus (image below).

(Bild: AP)

Unlike in previous studies, this time the team also determined more precisely which animals were present in the market stalls most contaminated with the coronavirus. This enabled them to draw up a "shortlist" of potential carriers and their origin.

"Last piece of the puzzle in a relatively clear picture"
"We have analyzed the data in a new, thorough way and show how it fits with the rest of the evidence we already have about the start of the pandemic," says Worobey. "It's a final piece of the puzzle in what is already a relatively clear picture," he says.

The latest analysis of the data revealed that SARS-CoV-2 was present in some of the stalls where wild animals were also sold at the market. These wild animals included raccoon dogs and civets In some cases, genetic material from the coronavirus and these animals was found on the same swabs.

The researchers also conducted an evolutionary analysis of the earliest viral genomes reported. The results suggest that very few people - if any - were infected before the outbreak of the pandemic. That argues for transmission from animals to humans in the marketplace and subsequent spread in Wuhan and eventually around the world, Worobey said.

"The spark in a tinderbox"
 Bringing wild animals infected with viruses into contact with humans in the heart of large cities, where population density makes it easy for pathogens to take hold, they one of the riskiest things humans can do, Worobey said.

"Not all of these viruses have the potential to cause a pandemic, but if you bring them in, it's like a spark in a tinderbox" (tinder is a very flammable material used to start fires; note), the researcher said.