What are the symptoms of China's coronavirus?

Medical staff transfer a patient of a suspected case of a new coronavirus at the Prince of Wales Hospital in Hong Kong, China January 22, 2020. (cnsphoto via REUTERS)

China’s mysterious coronavirus is spreading fast.

Virtually unheard of a month ago, the new strain has crossed international borders, with confirmed cases in the US, Japan, South Korea, Thailand and Taiwan.

The death toll stood at 17 on Thursday, all in the city of Wuhan in Hubei province, which is at the epicentre of the outbreak.

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Chinese authorities confirmed 630 people are battling the virus, however, one expert claims numbers could be as high as 9,700 in Wuhan alone.

The disease may have reached the UK, with four suspected sufferers being tested in Scotland.

What are the symptoms of the new coronavirus?

Coronaviruses are a strain of pathogens that include everything from the mild common cold to life-threatening epidemics like severe acute respiratory syndrome (Sars).

Like all coronaviruses, the new strain - 2019-nCoV - starts with flu-like symptoms.

These include fever, cough, shortness of breath and breathing difficulties.

Symptoms can come on in as little as two days or as long as two weeks after exposure, according to the Centers for Disease Control and Prevention.

READ MORE: How did China's coronavirus outbreak start?

Warning signs can be difficult to distinguish from seasonal flu, said Professor Calum Semple from Alder Hey Children's Hospital.

In severe cases, patients develop pneumonia, which can be life-threatening.

This can come on suddenly over one-to-two days or develop slowly.

Pneumonia often causes a cough, which may come with thick coloured or blood-stained phlegm, according to the NHS.

Some develop breathing difficulties, with breaths becoming rapid and shallow.

Others may feel breathless, even when resting.

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A rapid heartbeat, fever, chest pain and loss of appetite are also warning signs.

Some also battle sweats and shivering, alongside generally feeling unwell.

Less common symptoms include coughing up blood, headaches, fatigue, nausea, vomiting, wheezing, and joint and muscle pain.

The elderly may become confused or disorientated.

Find out about the risks of the new coronavirus, where it came from and how it is treated here.