An outbreak of waterborne cryptosporidiosis caused by post-treatment contamination.
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.
Smith
H V
HV
Department of Bacteriology, Stobhill General Hospital, Glasgow.
Patterson
W J
WJ
Hardie
R
R
Greene
L A
LA
Benton
C
C
Tulloch
W
W
Gilmour
R A
RA
Girdwood
R W
RW
Sharp
J C
JC
Forbes
G I
GI
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