SYDNEY — A virus that caused a spate of vomiting and diarrhea in Asia last winter appears to be spreading globally, threatening larger outbreaks of gastro infections that are a bane of luxury cruises.

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 Thursday. That means the bug, which kills about 800 people in an average year in the U.S., could sicken hundreds of millions of people worldwide 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 in case of a potential increase of norovirus activity in the next seasons” caused by this novel strain.

Norovirus made headlines last month when an outbreak of gastroenteritis on Fred.Olsen Cruise Lines’ flagship vessel, the Balmoral, sickened “hundreds” of people in Scandinavia. A gastro outbreak occurred on the same ship the previous month. Norovirus was the culprit..

Norovirus infections, sometimes called “stomach flu” or “winter vomiting disease,” usually occur in winter.