Epidemiologic and Genotypic distribution of Noroviruses among children with Acute Diarrhea and Healthy Controls in a Low-income Rural Setting.

Background. Noroviruses are the most common cause of epidemic and endemic acute gastroenteritis (AGE) worldwide. The burden of norovirus disease in low-income settings is poorly understood. Methods. We tested stool samples from children less than 5 years of age with diarrhea who were admitted in a rural hospital in Bangladesh from 2010-2012 and from matched, healthy controls from the same catchment area. Results. Norovirus was detected in 109 (18%) of 613 children with diarrhea and in 30 (15%) of 206 healthy controls. Most (n = 118; 85%) norovirus infections belonged to genogroup II (GII). Of these, GII. 4 viruses were identified in 36 (33%) of the cases and in 6 (21%) of the controls. Other major genotypes included GII. 3 (13%), GII. 6 (11%), and GII. 13 (11%) in the cases and GII. 6 (17%) and GII. 2 (14%) in the controls. The greatest risk of severe norovirus disease (Vesikari score >= 11) was associated with GII. 4 infections. GII. 4 viruses were the predominant genotype detected during the winter (55%) and rainy season (23%), while GII. 3 (19%) and GII. 13 (19%) viruses were the most prevalent genotypes during the summer. Vomiting was significantly associated with GII. 4 infections, while longer durations of diarrhea were associated with GI. 3 infections. Conclusions. Future studies are needed to understand the high rates of virus shedding in children without AGE symptoms.