An acute gastroenteritis outbreak caused by norovirus in a middle school in Hubei province, China

Objective To analysis the epidemiological characters of an infectious diarrhea outbreak in a middle school in Hubei province, and to provide evidence for prevention and control measures. Methods Field epidemiological method was used in case definition and patient search. Samples from patients, kitchen workers and related environment were collected for laboratory testing. Descriptive epidemiology and case-control study were used in the analysis. Results Eighty-five cases were identified and the attack rate was 31.6% (85/269). The onset time of 71.8% (61/85) of the cases was 8:00 to 24:00 on February 15, 2017. Nucleic acid of norovirus was GⅡ positive in the anal swabs of 17 patients (including 16 students and 1 teacher) and in 2 cases of silent infection (kitchen workers). Case-control study suggested that breakfast on February 14, 2017 was a risk factor for onset (odds ratio = 21.77, 95%CI: 2.61-181.77). Conclusions The outbreak was associated with contamination by norovirus. Silent infection in kitchen workers may be associated with the outbreak. Key words: Norovirus; Diarrhea; Outbreaks; Epidemiology