NEW YORK — A new strain of stomach bug sweeping the globe is taking over in the U.S., health officials say.
Since September, more than 140 outbreaks in the U.S. 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.
The new strain is making people sick in Japan, Western Europe and other parts of the world. First identified last year in Australia, it is called the Sydney strain.
In the U.S., it is accounting for about 60 percent of norovirus outbreaks, according to a report released Thursday by the Centers for Disease Control and Prevention (CDC).
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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 in the U.S.
Ian Goodfellow, a 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.
Norovirus is spread by infected food handlers who don’t do a good job washing their hands after using the bathroom. But unlike salmonella and other foodborne illnesses, norovirus can also spread in the air, through droplets that fly when a sick person vomits.
Each year, noroviruses cause an estimated 21 million illnesses and 800 deaths, the CDC says.
For those infected, there’s really no medicine. They just have to ride it out for the day or two of severe symptoms, and guard against dehydration, experts said.