What Started Coronavirus Outbreak in China? Snakes Most Likely Source, Experts Believe

A mysterious new pneumonia-causing virus that has killed over a dozen people in China is thought to have originated in snakes, according to experts.

So far, 17 people have died and 555 cases of the illness have been confirmed across the world, including in the U.S., Japan, Thailand, and South Korea. Since the infection, dubbed 2019-nCoV, was identified in the central Chinese city of Wuhan in December, scientists have been working hard to gain an understanding of its origins and characteristics.

The virus was first reported among people who worked at a seafood market in the Hubei Province city, where live animals were sold. As information about the nature of the virus emerged, experts updated their view that it could only spread from animals to humans, to state it could spread from person to person.

Paul Hunter, a professor in medicine at the U.K.'s Norwich School of Medicine, University of East Anglia, told Newsweek that it is still not clear what the source of the virus was, and "it may never be definitively proved."

He said: "The virus has already been detected in both bats and snakes prior to this outbreak and the strains in both bats and snakes are similar to each other and the strains from human cases. Human cases are more like the strains in snakes so that is the more likely."

To understand the source of a virus, Hunter explained, experts compared the gene sequence of the new virus with those that already exist.

"This is probably as good evidence as we will get," he said. "Ideally we would like to isolate the virus from food animals in the market, but it is likely that the infected batch of animals are long gone.

Hunter suggested that at this stage in its proliferation, "the big question is no longer where it came from but how and where it is spreading in human populations."

In recent days, unverified videos have emerged showing people eating bats that have been pinned to the outbreak. But Hunter said cooked food is unlikely to be the source of the virus.

"I suspect the most likely transmission pathway would be from aerosols produced during handing of the live animals and during butchery and food preparation, which would then be inhaled or contaminate surfaces that would then be touched by people. However, raw food is also a risk," he said.

Asked if he is worried about the virus, Hunter said: "That depends on what you compare it to. A typical influenza epidemic can kill many tens of thousands and sometimes hundreds of thousands of people. Previous novel coronavirus outbreaks had caused the death of substantially few people [SARS killed about 800 people globally and MERS about 450]."

"This new strain seems to be rather less lethal than the previous two outbreaks, however, this could still change," he said.

"All new outbreaks are worrying, especially in the early weeks when it is not clear how the outbreak could progress."

However, Hunter said he doubts the outbreak will develop into a pandemic, "though we still do need to take the outbreak seriously and monitor the situation carefully."

2019-nCoV is a member of the coronavirus family that can cause conditions as mild as the common cold to more severe infections like Severe Acute Respiratory Syndrome (SARS).

Dr. Andrew Freedman, reader in infectious diseases and honorary consultant physician at Cardiff University in the U.K., told Newsweek animal sources are typical of this group of bugs as the viruses have a high propensity to mutate. "It is this that allows them to infect other species including humans," he said.

"In the case of SARS in 2002, it was civet cats that passed the virus to humans, but they are thought to have been infected by bats," said Freedman.

He explained that although the death toll has risen in recent days, the overall mortality rate is still relatively low, "suggesting the infection is less virulent than SARS.

"There may be lots more milder cases that have not been diagnosed and it has been stated that those who have died have had significant underlying medical problems (weakened immune systems, chronic respiratory diseases etc)."

Freedman added: "The concern is that further mutation of the virus may render it both more contagious, potentially leading to a global epidemic, and or more virulent leading to more severe illness/higher mortality even in previously healthy people—time will tell."