Open AccessShigellosis Outbreak Associated with Contaminated Well Water in a Rural Elementary School: Sichuan Province, China, June 7–16, 2009
Author(s) -
Fan He,
Ke Han,
Lun-guang Liu,
Wei Sun,
Lijie Zhang,
Bao-Ping Zhu,
Hongxia Ma
Publication year - 2012
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0047239
Subject(s) - shigellosis , shigella flexneri , outbreak , shigella , odds ratio , medicine , environmental health , transmission (telecommunications) , veterinary medicine , demography , biology , virology , bacteria , salmonella , biochemistry , genetics , escherichia coli , gene , electrical engineering , engineering , sociology
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.