Investigation of acute gastroenteritis outbreak in a rural boarding primary school

Summary

Background: On May 6, 2011, we received a report of an outbreak of gastroenteritis in a rural boarding primary school. We undertook an epidemiological investigation to identify risk factors for illness, recommend prevention measures, and prevent future outbreaks. Methods: We implemented a cross-sectional survey and a case-control study. A case was defined as onset of diarrhea (≧3 times/24 hours) from May 1 to 10 in a student or staff of the school. A control-person was a student or staff without any symptoms during the same period. Results: We identified 26 cases, attack rate: 9.1%, all among boarding students in grades 3 to 6. Most common symptoms were: abdominal pain (92%) and diarrhea (88%), while 8% reported fever. The epidemic curve showed a single peak and an interval of 5 hours between the onsets of the first and last cases. Accordingly, we focused the investigation on at breakfast 4 hours before and dinner 16 hours before the outbreak peak. The study showed 77% of case-students ate >3 steamed bu