China coronavirus: Calls to ban live animal sales in wet markets to halt future outbreaks

The novel coronavirus 2019-nCoV, which is at the heart of an outbreak of viral pneumonia centred on Wuhan in China, is likely to have originated from snakes bought from a wet market and eaten.

After comparing the genetic information of the virus with information already available on other viruses, scientists have found the disease appears to have formed from a combination of a coronavirus found in bats, and another coronavirus originating from snakes.

This unique mix of proteins changed the shape of the receptors that allow the virus to bind onto and infect cells. Researchers say this recombination may have allowed cross-species transmission from snakes to humans.

The research from China notes that patients infected with the virus were exposed to animals at a wholesale market, where seafood, poultry, snakes, bats and farm animals are sold.

“Results derived from our evolutionary analysis suggest for the first time that snake is the most ​probable wildlife animal reservoir for the 2019-nCoV​,” the authors wrote.

“New information obtained from our evolutionary analysis is highly significant for effective control of the outbreak caused by the 2019-nCoV-induced pneumonia​.”

Writing in the South China Morning Post​, Dr Martin Williams, stated: “​As long as such markets exist, the likelihood of other new diseases emerging will remain. Surely it's time for China to close down these markets. In one fell swoop, it would be making progress on animal rights and nature conservation, while reducing the risk of a “made in China” disease harming people worldwide.”​

Elsewhere, Phill Cassey, an associate professor at the Centre for Applied Conservation Science at the University of Adelaide, and an expert in the live animal trade, said the outbreak could have major consequences for the wider live animal trade – legal or otherwise.

"A bat and then snake origin for the novel​ coronavirus is definitely a very interesting hypothesis. Regardless of whether it has an origin in snakes or not, it will likely to be a disease that spreads from animals to humans​,” said Dr Cassey.

Among the highest risk sources for exposure are wildlife and bushmeat markets, which constitute a massive risk for novel emerging diseases.

“Globally there is increasing pressure for live animals, as well as products and derivatives, in the wildlife trade. In many cases the trade is unregulated and illegal with major risks to biodiversity and environments, including human health​,” he added.

According to Rietie Venter, the University of South Australia’s head of microbiology, this is the first time viral transmission from snake to human has been observed.

“The recent discovery that snakes are the most probable wildlife animal reservoir for this virus has implications for the possibility of other viral outbreaks linked to exotic pets or bushmeat​,” Dr Venter warned.

The work of EcoHealth Alliance, a New York wildlife and public health non-profit, shows that human activities are the factors driving outbreaks like coronavirus, according to its president, Peter Daszak.

Dr Daszak believes the wildlife trade has been creating unnatural interactions between people and wild animals, allowing the spread of viruses between the two.

What is needed to stop these new viruses gaining a foothold is more investment in prevention, which has been seen to be effective in the case of chronic diseases like heart and lung disease.

“We encourage expanded investment in prevention when it comes to infectious diseases as well, so that we can work to stop diseases like this one before they start making people sick​,” said Dr Daszak.

This could be done in the form of better sanitation in markets and publicising the risks of hunting, butchering and eating wildlife. In addition, better long-term health surveillance is needed for farmers and market workers in emerging disease hot-spots, and better surveillance for unknown viruses in wildlife.

“We need to do all of this prevention at the same time as we work on vaccines and drugs to cure the currently known viruses. That’s the best way to get ahead of pandemics​,” he added.