Waterborne Escherichia coli O157

The waterborne route of Vero cytotoxin-producing E. coli (VTEC) O157 infect ion was first suggested in two unconnected human cases in 1985. Since then, waterborne VTEC O157 has been identified in sporadic cases and in outbreak s of illness. Recreational waters, private and municipal supplies have been implicated from microbiological, environmental and epidemiological studies of cases. In addition, a research cohort study of farm workers identified exposure to private water supplies as a risk factor for having antibodies t o E. coli O157. Sources of contamination are thought to be animal and human faeces or sewage. The presence of low numbers of target organisms in water makes microbiological confirmation difficult, therefore epidemiological ev idence has been essential in outbreak investigations. Despite the potential for contamination of water with VTEC O157, waterborne infection is relativ ely rare largely due to the susceptibility of the organism to water treatme nt processes. This paper presents the evidence for waterborne VTEC O157 inf ection, considering current microbiological, environmental and particularly epidemiological information.