NEW YORK — A new strain of norovirus from Australia accounts for more than half of outbreaks around the country, according to the Centers for Disease Control and Prevention.

The CDC reported that the new strain of the virus, called GII.4 Sydney, was responsible for 53% of the 266 norovirus outbreaks reported through CaliciNet, an electronic laboratory surveillance network, between September and December 2012. The new strain emerged in Australia in March 2012. The other outbreaks resulted from other strains of the virus, including GII.4 New Orleans. The CDC noted that the new strain appears to have replaced GII.4 New Orleans, which had previously been the predominant strain.

Norovirus is a common cause of food poisoning and so-called stomach flu, causing gastroenteritis that leads to symptoms like nausea, stomach cramps, vomiting and diarrhea. It can be spread through direct human contact or contaminated food. Most people recover in one or two days, but the virus can cause serious complications and death in young children, the elderly and people with compromised immune systems.

Interested in this topic? Sign up for our weekly DSN Collaborative Care e-newsletter.