Abstract:

Objective To investigate a Sapovirus outbreak in a middle school in Tongzhou District，Beijing in 2025，analyze the causes and risk factors of the outbreak，and provide references for the prevention and control of acute gastroenteritis in schools. Methods Based on the characteristics of the gastroenteritis outbreak at the middle school from May 9 to 13，2025，we conducted a field epidemiological investigation，an environmental health investigation，and laboratory pathogen testing. Descriptive epidemiological methods were used to analyze the epidemiological characteristics of the outbreak，and a case-control study was employed to identify the risk factors associated with the outbreak. Results A total of 28 cases were identified，distributed across 5 classes. The attack rates for Class 12 to Class 16 of Senior Grade 2 were 1.96%，16.36%，11.43%，10.00%，and 25.71%，respectively（χ²=11.928，P<0.05）. The predominant clinical manifestations were vomiting（82.1%），nausea（82.1%），and abdominal pain（78.6%）. The number of cases was 24 in males and 4 in females，with attack rates of 17.14% and 2.74%，respectively （χ²=16.787，P<0.05）. The case-control study revealed that multiple visits to the male restroom on the 4th floor of the Senior Grade 2 teaching building on the 11th were a significant risk factor associated with the disease（OR=17.143，95%CI：1.780-164.883）. A total of 9 anal swab specimens from cases，3 anal swab specimens from close contacts，and 7 environmental surface swab specimens were collected. The results showed that 4 case specimens tested positive for Sapovirus nucleic acid，1 swab specimen from a female toilet pit tested positive for astrovirus nucleic acid，and all remaining specimens were negative. Conclusion This outbreak was an acute gastroenteritis outbreak caused by Sapovirus infection. The index case，who attended school while symptomatic，was suspected to be the source of infection. Inadequate decontamination of vomitus in the toilet was identified as the primary contributing factor to the spread of the outbreak. Preventive healthcare departments need to strengthen training for school staff and standardize the disinfection procedures for vomitus.

Key words: Infectious diarrhea, Acute gastroenteritis, Sapovirus, Outbreak, Risk factor, Epidemiology