Objective To investigate and analyze an outbreak of acute gastroenteritis due to norovirus infection in a school in Wuhan in March 2024, and provide reference for the management of similar outbreaks.

Methods Field epidemiological investigation was conducted to collect relevant information, and the clinical manifestations and epidemiological characteristics of the cases were described. At the same time, a case-control study was conducted to identify the cause of the outbreak. Anal swabs from the cases or other related persons and environmental samples were collected for gastrointestinal pathogen detection.

Results A total of 160 cases of acute gastroenteritis were found. The main clinical manifestations were vomiting (98.13%), followed by abdominal pain (58.75%), fever (43.75%), nausea (38.75%) and diarrhea (9.38%). The cases were 1 teaching staff (attack rate 0.83%) and 159 students (attack rate 9.52%). The spatial clustering of cases was obvious, and the differences in attack rate among different teaching buildings, floors and classes were significant (P<0.001). Toilet use on the third floor of Building C odds ratio (OR)=14.03, 95% confidence interval (CI): 5.65−34.84 was a risk factor for the outbreak. Five anal swab samples from students and ten smears taken from external environment (toilet and classroom on the third floor of building C) were positive for norovirus GⅡ.

Conclusion This was an outbreak of acute gastroenteritis caused by norovirus GⅡ transmitted from person to person. Exposure to unsterilized toilets on the third floor of Building C was the main risk factor for the outbreak. It is suggested for schools and other collective units to conduct case isolation, timely epidemic reporting, environmental disinfection and take other prevention and control measures when such outbreak occur.