No 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.

Infections and life-threatening complications due to verotoxin-producing Escherichia coli (VTEC) have been increasingly recognized as a public health problem in recent years. Through enhanced surveillance in Alberta, Canada, and in Scotland, 1,993 cases of VTEC infection and 115 cases of hemolytic-uremic syndrome (HUS) were detected in 1987-1991 in a combined population of more than 7.5 million; there were 24 deaths. The mean annual rates of VTEC infection were 12.1/100,000 and 2.0/100,000 for Alberta and Scotland, respectively. One case of HUS occurred for every 14 (Scotland) to 19 (Alberta) cases of VTEC infection. Rates of VTEC infection were highest among children < 5 years of age, while rates of resultant hospitalization were highest among the elderly. Male-to-female ratios for patients with VTEC infection varied with the age group. The incidence of this infection was highest in the summer: 64.0%-81.7% of cases occurred between May and September. Hamburger was the most common source reported. Unexplained geographic variation in prevalence was evident in both Alberta and Scotland. Most cases were sporadic, although several community and point-source outbreaks were identified in Scotland. HUS exhibited similar epidemiological patterns. Infections with VTEC impose a substantial preventable clinical and public health burden. Routine monitoring of these infections is considered worthwhile in order to elucidate their epidemiology and modes of transmission and ultimately to control them more effectively.

SUMMARYIn May 1992, a small, circumscribed community outbreak of infection due to verotoxin-producing Escherichia coli 0157 phage type 49 occurred in a semi-rural area of south-east Scotland. On the basis of stool cultures, six cases were identified, one of whom was asymptomatic. One child developed the haemolytic uraemic syndrome. Although the source of infection of the index case was not established nor could the extent of person-to-person spread be fully determined, the clinical, microbiological and epidemiological evidence available indicated that a children's paddling pool served as the focal point in the transmission of infection causing the outbreak.