title: [An outbreak of gastroenteritis caused by contaminated well water in a village, Henan province].
abstract: OBJECTIVE
  To identify the cause and mode of transmission of a gastroenteritis outbreak in a village, Henan province.
  
  
  METHODS
  Gastroenteritis patients were identified through family visits, interviewing the village doctors and reviewing diagnosis and prescription records at the village health clinic. Cases were defined as onset of one of the four symptoms from the village resident during July 20 to August 12, 2010. The symptoms would include diarrhea (≥ 3 times/day), abdominal pain, nausea or vomiting. A retrospective cohort study was conducted to assess the association between drinking raw well water or eating noodles rinsed by raw well water and gastroenteritis. Stools or vomits of the case-patients and the well water samples were tested for bacterial pathogens.
  
  
  RESULTS
  Data for 60 case-patients were collected. All cases occurred in the northern part of the village. Persons who used water from a public well in the northern part of the village had an attack rate of 55%, which was 3.5 times of those who did not use the well water (16%) (RR = 3.5, 95%CI: 1.2 - 10). Results from the retrospective cohort study showed that drinking un-boiled water from the well was a risk factor (RR = 1.7, 95%CI: 1.3 - 2.3). Laboratory testing showed that total coliform and E. coli both greatly exceeded the limit considered safe for drinking, indicating there was fecal contamination in the well water. No bacterial pathogens were detected in the patients' stools or vomits.
  
  
  CONCLUSIONS
  The outbreak was mainly caused by drinking contaminated water from the public well in the northern part of the village.
authors.affiliation: Chinese Field Epidemiology Training Program (CFETP), Chinese Center for Disease Control and Prevention, Beijing 100050, China; Dalian Municipal Center for Disease Control and Prevention, Liaoning province.
authors.forename: Xi-Hong
authors.initials: XH
authors.lastname: Jiang
authors.forename: Peng
authors.initials: P
authors.lastname: Tian
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Duan
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Qian
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Li-Jie
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Hui-Lai
authors.initials: HL
authors.lastname: Ma
authors.forename: Bao-Ping
authors.initials: BP
authors.lastname: Zhu
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
mesh_terms: D015331:Cohort Studies; D004196:Disease Outbreaks; D004926:Escherichia coli; D005759:Gastroenteritis / Q000453:epidemiology; D006801:Humans; D012189:Retrospective Studies; D014871:Water Microbiology; D014881:Water Supply