Viral Etiology of Acute Gastroenteritis in <2-Year-Old US Children in the Post-Rotavirus Vaccine Era

Background. The rotavirus disease burden has declined substantially since rotavirus vaccine was introduced in the United States in 2006. The aim of this study was to determine the viral etiology of acute gastroenteritis (AGE) in US children aged <2 years. Methods. The New Vaccine Surveillance Network (NVSN) of geographically diverse US sites conducts active pediatric population-based surveillance in hospitals and emergency departments. Stool samples were collected from children aged <2 years with symptoms of AGE (n = 330) and age-matched healthy controls (HCs) (n = 272) between January and December 2012. Samples were tested by real-time reverse-transcriptase polymerase chain reaction assays {adenovirus (type 40 and 41), norovirus, parechovirus A, enterovirus, sapovirus, and astrovirus} and an enzyme immunoassay (rotavirus). All samples that tested positive were genotyped. Results. Detection rates of pathogens in children with AGE versus those of HCs were, respectively, 23.0% versus 6.6% for norovirus (P<.01), 23.0% versus 16.0% for adenovirus (P=.08), 11.0% versus 16.0% for parechovirus A (P=.09), 11.0% versus 9.0% for enterovirus (P=.34), 7.0% versus 3.0% for sapovirus (P=.07), 3.0% versus 0.3% for astrovirus (P=.01), and 3.0% versus 0.4% for rotavirus (P=.01). A high prevalence of adenovirus was detected at 1 surveillance site (49.0% for children with AGE and 43.0% for HCs). Norovirus GII.4 New Orleans was the most frequently detected (33.0%) norovirus genotype. Codetection of >1 virus was more common in children with AGE (16.0%) than in HCs (10.0%) (P=.03). Conclusions. Norovirus, astrovirus, sapovirus, and rotavirus were detected significantly more in children with AGE than in HCs, and norovirus was the leading AGE-causing pathogen in US children aged <2 years during the year 2012.