OUTBREAKS OF WATERBORNE INFECTIOUS INTESTINAL DISEASE IN ENGLAND AND WALES, 1992-5

Following the introduction of an improved surveillance system for infe ctious intestinal disease outbreaks in England and Wales, the Public H ealth Laboratory Service Communicable Disease Surveillance Centre rece ived reports of 26 outbreaks between 1 January 1992 and 31 December 19 95 in which there was evidence for waterborne transmission of infectio n. In these 26 outbreaks, 1756 laboratory confirmed cases were identif ied of whom 69 (4 %) were admitted to hospital. In 19 outbreaks, illne ss was associated with the consumption of drinking water from public s upplies (10 outbreaks) or private supplies (9 outbreaks). The largest outbreak consisted of 575 cases. In 4 of the remaining 7 outbreaks, il lness was associated with exposure to swimming pool water. Cryptospori dium was identified as the probable causative organism in all 14 outbr eaks associated with public water supplies and swimming pools. Campylo bacter was responsible for most outbreaks associated with private wate r supplies. This review confirms a continuing risk of cryptosporidiosi s from chlorinated water supplies in England and Wales, and reinforces governmental advice to water utilities that water treatment processes should be rigorously applied to ensure effective particle removal. Hi gh standards of surveillance are important for prompt recognition of o utbreaks and institution of control measures. As microbiological evide nce of water contamination may be absent or insufficient to implicate a particular water supply, a high standard of epidemiological investig ation is recommended in all outbreaks of suspected waterborne disease.