High prevalence and genetic diversity of noroviruses among children with sporadic acute gastroenteritis in Nanning City, China, 2010-2011.

A molecular epidemiological study of Norovirus (NoV) infections in children aged <5 years was conducted in the outpatient department of a hospital between January 2010 and December 2011 in Nanning City, Guangxi Zhuang Autonomous Region of China. Fecal samples were collected from 354 pediatric patients with acute gastroenteritis, and were screened for the presence of NoV with one-step real-time reverse-transcription polymerase chain reaction (RT-PCR). NoV genogroup II (GII) was detected in 28.5% (101/342) of samples, but no NoV GI was found. Eighty-four of the NoV GII strains were successfully sequenced, and they were clustered into seven genotypes: GII.4 (77.4%), GII.2 (8.3%), GII.14 (4.8%), GII.7 (3.6%), GII.3 (2.4%), GII.6 (2.4%), and GII.12 (1.2%). The predominant GII.4 variant in circulation was variant 2006b (92.3%). Importantly, the emergence of variant GII.4 2010 was detected. NoV was detected throughout the year, but mainly during the cold months. The highest prevalence of NoV was detected in young children aged <2 years. The NoV detection rates did not differ significantly in males and females. This is the first report to demonstrate the high prevalence and genetic diversity of NoVs in children with sporadic acute gastroenteritis in Nanning. Our study findings indicate the need for continual surveillance to monitor epidemiological changes and potential new variants of these viruses.