Stomach illness hitting the U.S.

NEW YORK — A new strain of stomach bug sweeping the globe is taking over in the United States, health officials say.

Since September, more than 140 outbreaks in the United States have been caused by the new Sydney strain of norovirus. It may not be unusually dangerous; some scientists don't think it is. But it is different, and many people might not be able to fight off its gut-wrenching effects.

Clearly, it's having an impact. The new strain is making people sick in Japan, Western Europe, and other parts of the world. It was first identified last year in Australia and called the Sydney strain.

In the United States, it is now accounting for about 60 percent of norovirus outbreaks, according to report released Thursday by the Centers for Disease Control and Prevention.

Norovirus – once known as Norwalk virus – is highly contagious and often spreads in places such as schools, cruise ships and nursing homes, especially during the winter. Last month, 220 people on the Queen Mary II were stricken during a Caribbean cruise.

Sometimes mistakenly called stomach flu, the virus causes bouts of vomiting and diarrhea for a few days.

Every two or three years, a new strain evolves – the last was in 2009. The Sydney strain's appearance has coincided with a spike in influenza, perhaps contributing to the perception that this is a particularly bad flu season.

Ian Goodfellow, a prominent researcher at England's University of Cambridge, calls norovirus the Ferrari of viruses for the speed at which it passes through a large group of people.

It can sweep through an environment very, very quickly. You can be feeling quite fine one minute and within several hours suffer continuous vomiting and diarrhea, he said.

Health officials have grown better at detecting new strains and figuring out which one is the culprit. They now know that norovirus is also the most common cause of food poisoning in the United States.

It's spread by infected food handlers who don't do a good job washing their hands after using the bathroom. But it can also spread in the air, through droplets that fly when a sick person vomits.