Hospital-based Surveillance for Pediatric Norovirus Gastroenteritis in Bangladesh, 2012-2016

Background: Globally, noroviruses are recognized as an important cause of acute gastroenteritis (AGE), but data from low and middle-income countries are limited. Aims: To examine the epidemiology and strain diversity of norovirus infections among children hospitalized for AGE in Bangladesh. Methods: We implemented active surveillance of children <5 years of age hospitalized with AGE at 8 geographically dispersed tertiary care hospitals in Bangladesh from July 2012 to June 2016. We tested random samples of AGE cases stratified by site and age group for norovirus by real-time RT-PCR. Noro-positive specimens were genotyped. Coinfection with rotavirus was assessed based on prior EIA testing. Results: We enrolled 5622 total AGE cases, of which 1008 were tested for norovirus. Total of 137 (14%) AGE cases tested positive for norovirus (range, 11%-17% by site). Most (94%) norovirus-associated hospitalizations were among children less than 2 years of age. Norovirus was detected year-round, with higher detection from March to June (20%-38%) and November to January (9%-18%). Genogroup II (GII) noroviruses were detected in 96% of cases, and the most frequent genotypes were GII.4 Sydney [P4 New Orleans] (33%), GII.3 [P16] (20%), and GII.4 Sydney [P16] (11%). The proportion of norovirus-positive specimens was significantly greater among rotavirus-negative AGE patients compared with rotavirus-positive AGE patients (27% vs. 5%, P < 0.001). As measured by the Vesikari severity score, a similar proportion of norovirus and rotavirus positive AGE patients were considered severe (68% vs. 70%, P = 0.86). Conclusions: Norovirus is an important cause of AGE hospitalization in Bangladeshi children with most infections caused by GII viruses.