Investigation of an outbreak of gastroenteritis caused by co-infection of norovirus GⅠ and GⅡ in a school in Jinghong, Yunnan

  Objective  To investigate an outbreak of acute gastroenteritis caused by norovirus in an primary school in Jinghong, Yunnan province, and provide evidence for the prevention and control of norovirus infection.

  Methods  Field epidemiological survey and case survey were conducted to collect the basic information of the school and case information in Jinghong, Yunnan province. Anal swabs of the cases, food and drinking water samples were collected for enterovirus nucleic acid detection. The comparison of the rates were done by χ² test.

  Results  During February 19–22 , 2023, a total of 24 confirmed cases of acute gastroenteritis were reported, including 16 girls and 8 boys, with an attack rate of 4.05%. The attack rate was 5.13% in girl students and 2.85% in boy students, the difference was not significant (χ²=1.981, P＝0.159). The epidemic curve indicated a point source outbreak, 14 cases occurred in grade 4, accounting for 58.33%. The difference was significant compared with other grades (χ²= 15.563, P＝0.008). Three classes with more cases were all distributed on the left side of the second floor of the teaching building, the difference was significant compared with other classes (χ²=27.449, P＝0.002). The main symptoms were diarrhea (100.00%), abdominal pain (95.83%). Case-control study showed that failure to wash hands after pressing button of water container was the main factor causing the spread of the epidemic, showing a statistical association with the incidence of the disease (OR=12.14). In 32 anal swabs, 7 were positive for norovirus (4 were positive for GⅡand 3 were positive for GⅠ).

  Conclusion  This outbreak might be caused by co-infection of norovirus GⅠand GⅡ imported by students returning from vacation and spread due to poor hand hygiene of students in dry season.