title: An outbreak of waterborne cryptosporidiosis caused by post-treatment contamination.
abstract: An outbreak of waterborne cryptosporidiosis affecting 27 persons, diagnosed stool positive, occurred in Ayrshire in April 1988. Twenty-one in 27 confirmed cases required some form of fluid replacement therapy. Local general practitioners indicated a two- to fivefold increase in diarrhoeal disease during the outbreak, and following enquiries made by Environmental Health Officers it became apparent that many hundreds of people had suffered a diarrhoeal illness at that time. Cryptosporidium spp. oocysts were detected in the treated chlorinated water supply system, in the absence of faecal bacterial indicators. Oocyst contamination of a break-pressure tank containing final water for distribution was the cause of this waterborne outbreak. An irregular seepage of oocyst-containing water, which increased during heavy rains, was the cause of the break-pressure tank contamination, rather than a failure of the water-treatment processes. The waterborne route should be considered when clusters of cryptosporidiosis-associated with potable water occur. Waterborne cryptosporidiosis can occur in the absence of other faecal indicators of contamination.
authors.affiliation: Department of Bacteriology, Stobhill General Hospital, Glasgow.
authors.forename: H V
authors.initials: HV
authors.lastname: Smith
authors.forename: W J
authors.initials: WJ
authors.lastname: Patterson
authors.forename: R
authors.initials: R
authors.lastname: Hardie
authors.forename: L A
authors.initials: LA
authors.lastname: Greene
authors.forename: C
authors.initials: C
authors.lastname: Benton
authors.forename: W
authors.initials: W
authors.lastname: Tulloch
authors.forename: R A
authors.initials: RA
authors.lastname: Gilmour
authors.forename: R W
authors.initials: RW
authors.lastname: Girdwood
authors.forename: J C
authors.initials: JC
authors.lastname: Sharp
authors.forename: G I
authors.initials: GI
authors.lastname: Forbes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003457:Cryptosporidiosis / Q000453:epidemiology* / Q000209:etiology; D003458:Cryptosporidium / Q000302:isolation & purification; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011891:Rain; D012606:Scotland / Q000453:epidemiology; D014881:Water Supply