A Waterborne Outbreak of Escherichia coli O157:H7 Infections and Hemolytic Uremic Syndrome: Implications for Rural Water Systems

摘要

In the summer of 1998, a large outbreak of Escherichia coli O157:H7 infections occurred in Alpine, Wyo-ming. We identified 157 ill persons; stool from 71 (45%) yielded E. coli O157:H7. In two cohort studies, ill-ness was significantly associated with drinking municipal water (town residents: adjusted odds ratio=10.1,95% confidence intervals [CI]=1.8-56.4; visitors attending family reunion: relative risk=9.0, 95% CI=1.3-63.3). The unchlorinated water supply had microbiologic evidence of fecal organisms and the potential forchronic contamination with surface water. Among persons exposed to water, the attack rate was signifi-cantly lower in town residents than in visitors (23% vs. 50%, p<0.01) and decreased with increasing age.The lower attack rate among exposed residents, especially adults, is consistent with the acquisition of par-tial immunity following long-term exposure. Serologic data, although limited, may support this finding. Con-tamination of small, unprotected water systems may be an increasing public health risk