[Etiology and epidemiological characteristics of viral diarrhea in Guangzhou, 2020-2023]

Objective: To analyze the etiology and epidemiological characteristics of viral diarrhea in Guangzhou from 2020 to 2023, and to provide reference for the surveillance and prevention of viral diarrhea. Methods: Stool specimens were collected from children and adults in sentinel hospitals in Guangzhou from 2020 to 2023. Real-time PCR was performed to detect nucleic acid of norovirus, group A rotavirus, sapovirus, astrovirus and enteric adenovirus. Subsequently, the nucleic acid-positive specimens were further sequenced and genotyped. Statistical analysis was performed using SPSS 22.0 software. Results: A total of 1 889 diarrhea case samples were collected from 2020 to 2023, with a viral diarrhea pathogen positivity rate of 23.82% (450/1 889). The positivity rates for the five common diarrhea-associated viruses were as follows: norovirus 12.33% (233/1 889), group A rotavirus 7.20% (136/1 889), enteric adenovirus 3.76% (71/1 889), astrovirus 2.44% (46/1 889) and sapovirus 1.27% (24/1 889), with co-infection virus positivity rate observed in 3.44% (65/1 889) of cases; Significant differences in the positivity rates for single-virus and the viral diarrhea pathogen positivity rate were noted across different years (all P<0.05). Specifically, the positivity rates for norovirus, sapovirus, astrovirus, and co-infections peaked in 2023, while group A rotavirus and enteric adenovirus reached their higher levels in 2021. Notably, Viral diarrhea exhibits a biennial outbreak pattern, with higher pathogen positivity rates observed in 2021 and 2023 compared to the preceding years. Seasonal analysis indicated that autumn and winter were the predominant periods for viral diarrhea, with norovirus peaking from September to March of the following year, and group A rotavirus peaking from January to March. Children aged 0-5 years exhibited greater susceptibility to group A rotavirus and enteric adenovirus, whereas the positivity rates for astrovirus and co-infections were higher in the 6-59 years age group. Individuals under 60 years old were particularly susceptible to norovirus. Genotypic analysis identified norovirus strains GⅡ.4[P31] and GⅡ.4[P16] as the predominant strains, with the GⅡ.3[P25] variant also detected in 2023. For group A rotavirus, G8P[8] and G9P[8] were the major genotypes, although G8P[8] has supplanted G9P[8] as the dominant subtype since 2022. The predominant genotypes for sapovirus, astrovirus, and enteric adenovirus were GⅠ.1, HAstV-1, and HAdV-41, respectively. Conclusions: The primary pathogens of viral diarrhea in Guangzhou are norovirus and group A rotavirus, with infection rates peaking during the autumn and winter months, 2020-2023. Both the positivity rates of viral diarrhea pathogens and co-infections have shown a significant upward trend. It is necessary to strengthen regional surveillance of viral diarrhea and implement health education as well as scientific prevention and control for susceptible populations.