Investigation of latent infection of norovirus in canteen workers in primary and secondary schools in Haidian district, Beijing, 2019–2020

  Objective  To understand the latent infection status of norovirus and the incidence of norovirus infection in canteen workers in primary and secondary schools in Haidian district of Beijing from 2019 to 2020, analyze the influencing factors of norovirus infection and provide scientific basis for effective prevention and control of norovirus infection.

  Methods  Stratified sampling and cross-sectional survey were used to collect stool samples or anal swabs of canteen workers in primary and secondary schools for norovirus nucleic acid detection. At the same time, questionnaire survey was used to collect personal basic information and awareness of norovirus of the canteen workers. The latent infection status of norovirus in the canteen workers from 2019 to 2020 was statistically analyzed, and the influencing factors of the infection were further analyzed.

  Results  A total of 785 canteen workers from 30 primary and secondary schools participated in the survey. A total of 785 questionnaires were delivered, 777 were returned, in which 740 were valid (94.27%). Two norovirus nucleic acid positive samples were detected in 740 samples (0.27%). Through statistical analysis, there were no significant differences in gender, age, education level, norovirus positive time, working clothes wearing, disposable mask wearing, hand washing before entering the food operation room, hand washing before meals, raw and cold seafood product eating, and hand washing after defecation, awareness of the risk of norovirus and medical care seeking due to acute gastroenteritis between positive group and negative group (P>0.05). There was significant difference in timely reporting acute gastroenteritis symptoms, such as vomiting and diarrhea, to canteen managers between positive group and negative group (χ²=27.044, P<0.05). The difference in incidence rate of norovirus infection between the canteen workers and non-canteen workers was significant (χ²=17.122, P＜0.05). The differences in positive rate among schools reporting epidemics were significant (χ²=61.750, P＜0.05).

  Conclusion  The latent infection rate of norovirus in canteen workers in primary and secondary schools in Haidian district was 0.27%, indicating the risk of the epidemic caused by norovirus infection. Therefore, it is necessary to strengthen the health education about norovirus infection prevention and health status monitoring in canteen workers, the timely reporting and isolation of the cases with gastrointestinal symptoms. In the period with high incidence of norovirus infection, regular sampling detection should be conducted in canteen workers, and strict isolation measures of positive cases should be implemented to effectively prevent the incidence and spread of norovirus infection.