Shigellosis outbreak associated with contaminated well water in a rural elementary school: Sichuan Province, China, June 7-16, 2009

PLoS One. 2012;7(10):e47239. doi: 10.1371/journal.pone.0047239. Epub 2012 Oct 10.

Abstract

Objectives: We investigated a shigellosis outbreak in an elementary school to identify the source of infection, mode of transmission and risk factors for illness.

Methods: In a case-control investigation, we compared the source of drinking water, consumption of untreated well water and suspected food items, and hygienic habits between case-students and randomly selected asymptomatic control-students, frequency-matched by class on a 1:1 ratio.

Results: 18% of the 533 students and no teachers developed Shigella. 52%(44/85) of case-students and 17% (12/71) of control-students drank untreated well water (OR = 2.3, 95% CI = 1.1-5.8); 47% (n = 40/85) of case-students and 14% (10/71) of control-students drank untreated water from Well A (OR = 3.7, 95% CI = 1.3-11). The odds ratio increased with the amount of untreated Well A water consumed (p = 0.035, χ(2) test for trend). Rectal swabs from 5 of 6 case-students and water from Well A yielded Shigella flexneri 2b.

Conclusions: This shigellosis outbreak was caused by drinking untreated water from a well polluted by Shigella flexneri 2b.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Case-Control Studies
  • Child
  • China / epidemiology
  • Disease Outbreaks*
  • Drinking Water / microbiology*
  • Dysentery, Bacillary / epidemiology*
  • Dysentery, Bacillary / transmission
  • Female
  • Humans
  • Male
  • Risk Factors
  • Rural Population*
  • Schools*
  • Shigella flexneri / isolation & purification

Substances

  • Drinking Water

Grants and funding

This investigation was supported by the Program for Zhejiang Leading Team of Science and Technology Innovation, and the General Funds for Emergency Public Health Response from the Ministry of Health of China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.