Molecular epidemiology of norovirus infection among children with acute gastroenteritis in Shanghai, China, 2001-2005.

Norovirus is one of the major causes of outbreaks and sporadic cases of acute gastroenteritis in young children worldwide. Obtaining local baseline information regarding this virus is important for developing and evaluating prevention strategies of norovirus transmission in children. The age, seasonal distribution and circulating genotypes of norovirus in Shanghai, China, between 2001 and 2005 were determined. Of 5411 stool specimens collected from children under 5 years of age who were hospitalized with acute gastroenteritis 3,975 were rotavirus-negative, indicating the presence of another causative agent. From these specimens, 484 were selected at random for genotyping, and 45 were norovirus-positive. Norovirus infection was detected in all age groups, but infants less than 6 months old showed the lowest prevalence (5.4%). Norovirus infections peaked from August to November. Among the 37 identified norovirus strains, 2 were GII-3, 2 were GII-7, and 33 were GII-4 genotypes. This study demonstrated the impact of norovirus infection causing acute gastroenteritis in hospitalized children and the importance of vaccination against norovirus diarrhea in Shanghai, China.