Molecular insights into viral agents of acute gastroenteritis detected among under five children in Assam, India.

Acute gastroenteritis (AGE) is a significant cause of morbidity and mortality among children under five years where viral agents are major contributors to AGE. Limited data exist on molecular epidemiology of viral gastroenteritis in northeastern India. The present study aimed to determine the prevalence and molecular diversity of major viral agents causing AGE in children under five years in Assam, India. A hospital-based prospective study was conducted from January 2022 to December 2023. Stool samples (n = 110) from children with AGE were screened for rotavirus A (RVA), adenovirus (HAdV), norovirus (NoV), astrovirus (HAstV) and sapovirus (SaV) using multiplex real-time Polymerase Chain Reaction, followed by genotyping and sequencing of selected isolates. Phylogenetic analysis was conducted to identify specific circulating strains. Enteric viruses were detected in 44.5 % (49/110) of samples. HAdV (16.36 %) was the most prevalent, followed by RVA (11.81 %), NoV GII (7.27 %), SaV (0.9 %) and HAstV (0.9 %). Mixed infections occurred in 14.55 %, mainly HAdV-NoV GII. Phylogenetic analysis identified HAdV species F (serotypes 40 and 41), NoV genotypes GII.4 and GII.2, RVA genotype G3P[8] and HAstV-1. HAdV-41 was the predominant adenovirus type, closely related to global strains. No correlation was found between mixed infections and disease severity. The predominance of HAdV-41 and exclusive detection of RVA G3P[8] reflect evolving viral epidemiology in the post-rotavirus vaccine era. Continuous molecular surveillance and strengthened WASH (water, sanitation and hygiene) interventions are essential to guide vaccine strategies and reduce the burden of viral gastroenteritis in young children in northeast India.