An outbreak of Shigella flexneri serotype 3c related to overcrowding in temporary dormitories of a primary School, Anhui, China, 2011


Background: On May 27, 2011, an outbreak of gastroenteritis reported in a primary school in Anhui province, China. We investigated this outbreak to identify the cause, mode of transmission and recommend control measure. Methods: A case was defined as diarrhea (≥3 liquid stools/24hours) plus ≥1 of the following: abdominal pain, fever (≥37.5℃), tenesmus, bloody or mucoid stool in a school student of staff since May 14, 2011. We collected stool samples and performed environmental inspection. We selected 61 cases and 58 controls frequency-matched on dormitories to compare their food, water exposure and personal hygiene habits. We estimated a crowding score in the dormitory using area per person as follows: 4.4 m2=1, 2.4 m2=2, 1.4 m2=3, 1.3 m2=4. Results: We identified 76 cases (Attack rate: 24%) over 8 days, all among boarding students. Boarding students had water and food source in common with other students and teachers. Stool specimens from 2 case-students and 1 healthy cafeteria worker