Zhinan Guo1, Jianwei Huang1, Guoqing Shi2, Cheng-hao Su1, Jian Jun Niu3. 1. Xiamen Center for Disease Control and Prevention, Fujian, People's Republic of China. 2. Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China. 3. Zhongshan Hospital, Xiamen University, Xiamen, Fujian, People's Republic of China. Electronic address: niujianjun62@163.com.
Abstract
OBJECTIVES: We investigated a diarrhea outbreak that occurred at a university in China to identify the etiological agent of the outbreak, source of infection, mode of transmission, and risk factors. METHODS: In this case-control study, we compared the food sources and examined the food and water items consumed between the probable and confirmed cases and the asymptomatic control students, who were selected randomly and frequency-matched by class and age at a ratio of 1:2. RESULTS: Out of 7141 students (excluding teachers), 87 (1.2%) developed an illness. Thirty-three of 44 (75%) cases and 11 of 88 (13%) control students had consumed bread products supplied by an unlicensed small bakery (odds ratio 21, 95% confidence interval 8-60). Norovirus GII was detected in seven patients and in a food handler at the bread workshop and his 8-month-old son. CONCLUSIONS: The outbreak of gastroenteritis was caused mainly by bread products contaminated with norovirus GII. A food handler with an asymptomatic norovirus GII infection was the possible source of infection.
OBJECTIVES: We investigated a diarrhea outbreak that occurred at a university in China to identify the etiological agent of the outbreak, source of infection, mode of transmission, and risk factors. METHODS: In this case-control study, we compared the food sources and examined the food and water items consumed between the probable and confirmed cases and the asymptomatic control students, who were selected randomly and frequency-matched by class and age at a ratio of 1:2. RESULTS: Out of 7141 students (excluding teachers), 87 (1.2%) developed an illness. Thirty-three of 44 (75%) cases and 11 of 88 (13%) control students had consumed bread products supplied by an unlicensed small bakery (odds ratio 21, 95% confidence interval 8-60). Norovirus GII was detected in seven patients and in a food handler at the bread workshop and his 8-month-old son. CONCLUSIONS: The outbreak of gastroenteritis was caused mainly by bread products contaminated with norovirus GII. A food handler with an asymptomatic norovirus GII infection was the possible source of infection.