Genetic diversity of noroviruses in Taiwan between November 2004 and March 2005

Noroviruses are a major health burden and are responsible for the majority of outbreaks of gastroenteritis in the world. Human noroviruses can be genetically divided into two main genogroups (GI and GII) and subdivided into many genotypes. In this study, stool specimens collected from 12 outbreaks of gastroenteritis in Taiwan were screened for viral agents between the 23rd of November 2004 and 9th of March 2005. Noroviruses were detected in all outbreaks. We detected six different norovirus genotypes: GI/11, GI/14, GII/3, GII/4, GII/6, and GII/18. Noroviruses belonging to GII/4 were dominant, 50 of 60 (83%) sequences, and were detected in 10 of 12 outbreaks. Furthermore, the norovirus GII/4 strains were detected throughout Taiwan, demonstrating their widespread distribution. We also found that three outbreaks had noroviruses from multiple genotypes. Our results have shown for the first time that noroviruses are an important cause of gastroenteritis in Taiwan.