一、案情简介 1993年7月15—19日,哈尔滨市南岗区某建材工业学校师生,陆续发生腹泻病人。市、区卫生防疫站接到报告后,立即赶往现场调查处理。对在校209人进行流行病学调查,有144人发病,发病率为69.9％;所有就诊师生具有相同的胃肠症状,疑为饮用水污染所致。故采取该校二次供水池和管网末梢水进行卫生学检验,细菌总数分别为250.000个/ml I. Brief introduction of the case July 15-19, 1993, Nangang District, Harbin City, a building materials industry school teachers and students, one after another diarrhea patients. City, District Health and Epidemic Prevention Station received a report immediately rushed to the scene investigation. Epidemiological survey of 209 people in the school, 144 were morbidity, the incidence was 69.9%; all teachers and students have the same gastrointestinal symptoms, suspected of drinking water pollution. So take the school secondary water supply pipelines and pipe network water hygiene tests, the total number of bacteria were 250.000 / ml