Shigellosis outbreak associated with contaminated well water in a rural elementary school: Sichuan Province, China, June 7-16, 2009.
OBJECTIVE
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.
Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, People's Republic of China.
Fan
F
He
Ke
K
Han
Lunguang
L
Liu
Wei
W
Sun
Lijie
L
Zhang
Baoping
B
Zhu
Huilai
H
Ma
D016022:Case-Control Studies; D002648:Child; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D060766:Drinking Water / Q000382:microbiology*; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000635:transmission; D005260:Female; D006801:Humans; D008297:Male; D012307:Risk Factors; D012424:Rural Population; D012574:Schools; D012763:Shigella flexneri / Q000302:isolation & purification
D060766:Drinking Water