Variations in Prevalence and Characteristics of Rotavirus Diarrhea Among Outpatients - Shanghai Municipality, China,...

This study investigated temporal changes in rotavirus group A (RVA) prevalence, epidemiological characteristics, and genotype distribution patterns among diarrhea outpatients in Shanghai Municipality, China.

We conducted prospective active surveillance of diarrheal disease in pediatric and adult outpatients in Shanghai. Stool specimens were analyzed for five viral and twelve bacterial pathogens. Real-time reverse transcription polymerase chain reaction (rRT-PCR) was employed for RVA detection, followed by genotyping of RVA-positive specimens through partial amplification of VP7 and VP4 genes.

The study analyzed 2,331 diarrhea cases in children aged 0-14 years and 8,418 cases in individuals aged ≥15 years between January 2017 and December 2023. Overall RVA positivity rates decreased significantly from 7.43% in 2017 to 1.19% in 2023 (P=0.024). The most pronounced decline occurred in children aged 2-5 years, where positivity rates fell from 13.08% to 1.72%. Adults aged ≥30 years also showed a substantial reduction. Among RVA-positive pediatric cases (≤14 years), the proportion of cases aged 6-14 years increased from 2.33% to 18.18%. While G9P[8] remained the predominant strain, its prevalence decreased from 77.78% to 31.25%, concurrent with the emergence of G8P[8] strains.

RVA prevalence has shown a marked decline since 2018-2019, accompanied by a shift in age distribution toward older children. The diminishing dominance of G9P[8] strains coincided with the emergence of G8P[8] strains. Continued epidemiological and genetic surveillance of rotavirus diarrhea, coupled with real-world effectiveness evaluations of domestic vaccines, remains crucial for optimizing rotavirus immunization strategies.