New norovirus strain spreads worldwide

Health officials said on Wednesday that a new strain of diarrhea- and vomiting-causing norovirus spread to New Zealand, Japan and France from Australia and may become the most dominant strain in Britain.

The strain, known as Sydney 2012, is now causing more cases in Wales and England than other strains. The variant does not cause worse symptoms than other strains. It causes violent and projectile vomiting, diarrhea and occasionally fevers, stomach cramps and headaches, Reuters reports.

"The emergence of a new strain does not mean that it causes more serious illness, and managing outbreaks and those with the illness remains the same," David Brown, the director of the virology reference department at the Health Protection Agency, said, according to Reuters. "Noroviruses mutate rapidly and new strains are constantly emerging. At the start of the season it is normal for outbreaks to be caused by a range of different strains. However, as the season progresses, particular strains are more successful and become dominant."

The number of norovirus cases rose earlier than anticipated during the winter in Britain, across Japan, Europe and other parts of the globe.

The HPA has reported 4,140 cases of norovirus so far this winter in England and Wales, a 63 percent increase from the same period last year. For each laboratory-confirmed case, scientists estimate approximately 288 unreported cases. Norovirus causes millions of infections annually around the world.

There is no particular treatment for norovirus infection aside from letting the illness take its course and staying hydrated. Symptoms typically last approximately two days, Reuters reports.