Increase in viral gastroenteritis outbreaks in Europe and epidemic spread of new norovirus variant.

During 2002 there were a high number of gastroenteritis outbreaks in hospitals and on cruise ships due to Noroviruses (NV). Data from 10 European countries was analysed and compared to historic data to investigate whether this reported activity was unusual. The data showed a striking increase and unusual seasonal pattern of NV gastroenteritis in 2002 that occurred concurrently with the emergence of a new genogroup II4 variant. The variant was first noted in January in Germany and Netherlands, and throughout 2002 became the predominant cause of NV outbreaks in Europe. The researchers were unable to explain how the variant spread but the dissemination was associated with a wave of person-to-person outbreaks. Lancet 2004;363:682-88.