Investigation on an outbreak of acute gastroenteritis caused by norovirus GⅡ in a company in Beijing, 2023

Objective To investigate and analyze an outbreak of acute gastroenteritis caused by GⅡ norovirus in a company in Beijing, 2023, understand its epidemiological characteristics, and provide evidence for the prevention and control of acute gastroenteritis outbreaks in the future.

Methods The basic information of the company where the outbreak occurred were collected, the data of cases were actively searched, the characteristics of the outbreak were analyzed by descriptive epidemiological methods, and case-control analysis was conducted to identify the transmission route and risk factors.

Results A total of 21 cases of acute gastroenteritis were reported, the attack rate was 5.77% (21/364). The main clinical manifestations were diarrhea (66.67%), vomiting (47.62%) and abdominal pain (19.05%). A total of 104 samples were collected for nucleic acid detections of norovirus, zarovirus, rotavirus, intestinal adenovirus and astrovirus, and 29 were positive for norovirus GⅡ nucleic acid, the positive rate was 27.88% (29/104). The distribution of cases showed spatial clustering, and there was significant difference in attack rate among workers on different building floors (χ²=33.786, P<0.05). There was significant difference in attack rate between company staff and canteen staff (χ²=29.217, P<0.05). Having lunch at staff canteen on April 25 was a risk factor for the infection (odds ratio=4.50, 95% confidence interval: 1.01−20.11).

Conclusion The outbreak was caused by GⅡ norovirus. It might be possible that a canteen staff still went to work after the infection, then resulting in secondary infections in canteen staff and company staff. It is suggested that the collective unit should take appropriate measures to strengthen staff health monitoring and conduct timely disinfection.