The number of people who have contracted a mysterious new virus from China has tripled over the weekend, with the outbreak spreading beyond its origin city of Wuhan.
Wuhan reported 136 new cases of the respiratory illness, while the Chinese capital Beijing reported two cases. Shenzhen confirmed one.
Three people have died, and more than 200 individual cases of infection have been reported. South Korea confirmed its first case of the virus on Monday, following two in Thailand and one in Japan.
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Health officials say that the virus, which first appeared in December, has been identified as a strain of coronavirus, and has led to an outbreak of viral pneumonia.
Officials and scientists say that much about the virus remains unknown, including how it has been spreading.
Experts in the UK told the BBC that the number of people infected could be far greater than the 200 confirmed by China, with estimates closer to 1,700.
The virus has brought back worrying memories of the 2003 Sars outbreak that originated in Chinese markets and killed more than 800 people worldwide in 2002 and 2003.
Where did the virus originate?
The World Health Organization says that the new virus probably spread from a seafood market in Wuhan, the capital of the central Chinese province of Hubei. The market also sells live birds and other animals.
But Japan’s health ministry says the man infected in the country had not been to the same market when he visited Wuhan, adding: “It is possible that he came in close contact with a person infected with the virus while in the city.”
Malik Peiris, a public health virologist at the University of Hong Kong, told The New York Times that “if that was the case, that there had been no direct exposure to animals, then that is very concerning, for sure”.
The virus has been given the official name 2019-nCoV, and is understood to be a new strain of coronavirus that has not previously been identified in humans.
Scientists have said that an animal source is “the most likely primary source”, but that it is likely some human-to-human transmission has already occurred.
People in the affected region are being advised to avoid “unprotected” contact with live animals and anyone with cold or flu-like symptoms. They are also being advised to thoroughly cook meat and eggs.
What are the symptoms?
The illness is a pneumonia-like respiratory illness, and a member of the large coronavirus family that cause infections ranging from the common cold to severe acute respiratory syndrome (known as Sars).
Common symptoms of coronavirus include a runny nose, headache, cough and fever. Shortness of breath, chills and body aches are associated with more dangerous kinds of coronaviruses, says The Guardian.
Is it expected to spread further?
The fact that the patients in Japan and Thailand say they had not visited the Huanan Seafood Market in Wuhan, where the virus is believed to have originated, is a worrying sign that the virus is spreading in the sprawling commercial centre and beyond.
Wuhan market was closed and disinfected on 1 January, but new cases have appeared since.
With a minimum incubation period for some viral infections of 15 days, there will have to be weeks with no new cases before health officials can determine the full extent of the outbreak.
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