Group C Rotavirus Gastroenteritis Outbreak in a Primary School - Luzhou City, Sichuan Province, China, October 2025

Group C rotavirus (RVC) infections occur globally, but are still considered a relatively rare cause of acute gastroenteritis compared to group A rotaviruses. Prior to this outbreak, RVC had not been reported in southwestern China, and routine surveillance predominantly focused on group A rotaviruses. Most characterized Chinese RVC strains belong to the M3 genotype.

This investigation documented the first laboratory-confirmed RVC outbreak in southwestern China, which affected 32 students across multiple grades. Spatiotemporal analysis linked the transmission cluster to shared school facilities, specifically classrooms adjacent to male restrooms on floors 2 to 5. Whole-genome sequencing revealed that all five sequenced strains shared an identical genotype (G4-P[2]-I2-R2-C2-M2-A2-N2-T2-E2-H2) with 0-1 single-nucleotide polymorphism differences, confirming a single-source transmission chain. Phylogenetic analysis revealed that the Luzhou strains belonged to the M2 genotype and clustered with recent strains from the Yunnan Province, Russia, and European countries, challenging the previous understanding that Chinese RVC strains predominantly belong to the M3 genotype.

Public health laboratories should enhance surveillance of non-group A rotaviruses in gastroenteritis outbreaks with negative group A results, particularly in school settings. Standardized control measures effective for norovirus outbreaks, including proper vomitus management, dedicated toilet facilities, and strict hand hygiene enforcement, successfully contained this RVC outbreak within one incubation period, and should be adopted for RVC outbreaks despite the absence of pathogen-specific guidelines.