The incidence of recreational water-associated outbreaks in the United States has significantly increased since national surveillance began in 1978. This increase has been driven by outbreaks caused by Cryptosporidium and associated with treated recreational water venues (e.g., pools). On August 9, 2004, Auglaize County Health Department staff detected several laboratory-confirmed cases of diarrhea caused by Cryptosporidium in a three-county area. Epidemiologic, laboratory, and environmental health methods were used to investigate the outbreak. While the outbreak was investigated and prior to final results being available, proactive prevention measures such as closure and hyperchlorination of pools and a community-wide education campaign were undertaken. The matched case-control study found that cryptosporidiosis was significantly associated with swimming in Pool A (matched odds ratio [mOR] 121.7, 95% confidence interval [CI] 27.4-∞) as were swimming, wading, or entering any swimming pool and swimming in or entering recreational water. Twenty-eight of 45 (62.2%) stool specimens tested were positive for Cryptosporidium by direct immunofluorescent assay and molecular typing of 18 isolates identified Cryptosporidium hominis, subtype IdA15G1. Samples taken from the deep and shallow ends of Pool A were positive for Cryptosporidium spp. by real-time polymerase chain reaction. This report records the first detection of Cryptosporidium hominis, subtype IdA15G1 in the United States. The results of the combined methods of this investigation indicate that Pool A was the cause of the outbreak. The findings also suggest a proactive public health response when increased Cryptosporidium transmission is detected and before an outbreak source is epidemiologically implicated might prevent a focal cryptosporidiosis outbreak from evolving into a community-wide outbreak.
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Table of Contents
Chapter II: Manuscript
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|Outbreak of Cryptosporidiosis Associated with a Swimming Pool, Auglaize County, Ohio, 2004 ()||2018-08-28||