Objective To investigate the cause of an acute gastroenteritis outbreak in an university in Shaanxi province in 2024, identify potential risk factors, and provide evidence to develop targeted prevention and control strategies to prevent similar outbreaks in the future.

Methods A descriptive epidemiological analysis was conducted on the distributions of the acute gastroenteritis cases, and a case-control study was performed to idenify the factors associated with the outbreak. Pathogen detection was conducted by using samples obtained from the cases, high-risk individuals, and potentially contaminated environments.

Results The outbreak lasted for 10 days, during which 134 cases were confirmed. The predominant clinical manifestations of the cases included nausea (89.55%), vomiting (83.58%), diarrhea (76.12%), abdominal pain (71.64%), and fever (52.99%). The attack rates in faculty and students were 0.69% (133/19 273) and 0.03% (1/3 761), respectively. The incidence curve indicated the intermittent same source exposure, and the spatial distribution of the cases clustered obviously in some dormitory buildings (χ² = 8.215, P = 0.042). The factor associated with the outbreak was having breakfast from the steamed bun stall on the first floor of canteen D on October 27 (OR = 2.17, 95% CI: 1.01-4.65) and October 28 (OR = 3.92, 95% CI: 1.94-7.93). The samples from 28 cases and 6 asymptomatic canteen workers, and 4 environmental swabs from the dormitory and 1 environmental swab from the steamed bun stall on the first floor of the canteen D were positive for norovirus GII. The genotype of the outbreak strain was identified as GII.17P17. The asymptomatic infection rate of norovirus in the workers on the first floor of canteen D was 12.00% (6 /50).

Conclusion This acute gastroenteritis outbreak was caused by norovirus GII.17P17. The workers preparing breakfast at the steamed bun stall were suspected to be the infection source, while having breakfast from this stall on October 28 was identifited as the main risk factor for the outbreak. It is suggested to include acute gastroenteritis symptoms into the daily health surveillance in canteen workers in universities. It is necessary to isolate the cases, report the cases timely, and conduct timely response to remove vomitus and disinfect contaminated areas when such outbreak occurs.