Norovirus strain from China with potential to infect millions spreads to United States, Europe and Africa.

A virus that caused vomiting and diarrhoea in Asia last winter appears to be spreading globally, threatening larger outbreaks of gastro infections that are the bane of luxury cruise liners.

The new strain of norovirus, known as GII.17, that emerged in southern China has the potential to spread widely because people will probably lack immunity to it, researchers in Japan said. The bug could make hundreds of millions of people worldwide sick as the highly contagious disease is transmitted by infected food and people.

"We know that noroviruses are able to rapidly spread around the globe," scientists from 16 countries wrote in a paper accompanying the Japanese research. "The public health community and surveillance systems need to be prepared."

Norovirus made headlines last month when an outbreak of gastroenteritis on Fred. Olsen Cruise Lines sickened hundreds of people in Scandinavia, prompting the cancellation of a subsequent three-night cruise from England. A gastro outbreak occurred on the same ship the month before and norovirus was to blame, the British-based firm said.

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Norovirus infections, sometimes called stomach flu or winter vomiting disease, usually occur in winter. An increase in the frequency of outbreaks on cruise ships over summer can predict a greater incidence in the community the following winter, said Marion Koopmans, a professor of public health virology at Erasmus University Medical Centre in Rotterdam, the Netherlands.

Outbreaks on cruise ships are especially noticeable because the contained environment and shared dining areas allow the disease to spread quickly - more than 80 per cent of passengers are often affected, according to World Health Organisation figures.

But most epidemics occur on land. Cases of GII.17 have been detected in the US, South America, Europe and Africa, Koopmans and colleagues wrote.

- Bloomberg