a1 Division of Parasitic Diseases, National Center of Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
a2 Epidemic Intelligence Service, Division of Applied Public Health Training, Epidemiology Program Office, Centers for Disease Control and Prevention, Atlanta, GA, USA
a3 Tazewell County Health Department, Tremont, IL, USA
a4 Illinois Department of Public Health, Springfield, IL, USA
a5 Illinois Department of Public Health, Chicago, IL, USA
Cryptosporidium has become increasingly recognized as a pathogen responsible for outbreaks of diarrhoeal illness in both immunocompetent and immunocompromised persons. In August 2001, an Illinois hospital reported a cryptosporidiosis cluster potentially linked to a local waterpark. There were 358 case-patients identified. We conducted community-based and waterpark-based case-control studies to examine potential sources of the outbreak. We collected stool specimens from ill persons and pool water samples for microscopy and molecular analysis. Laboratory-confirmed case-patients (n=77) were more likely to have attended the waterpark [odds ratio (OR) 16·0, 95% confidence interval (CI) 3·8–66·8], had pool water in the mouth (OR 6·0, 95% CI 1·3–26·8), and swallowed pool water (OR 4·5, 95% CI 1·5–13·3) than age-matched controls. Cryptosporidium was found in stool specimens and pool water samples. The chlorine resistance of oocysts, frequent swimming exposures, high bather densities, heavy usage by diaper-aged children, and increased recognition and reporting of outbreaks are likely to have contributed to the increasing trend in number of swimming pool-associated outbreaks of cryptosporidiosis. Recommendations for disease prevention include alteration of pool design to separate toddler pool filtration systems from other pools. Implementation of education programmes could reduce the risk of faecal contamination and disease transmission.
(Accepted March 31 2005)
(Online publication June 03 2005)
c1 Author for correspondence: Dr L. M. Causer, Division of Parasitic Diseases, National Center of Infectious Diseases, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Mailstop F-22, Atlanta, 30341, USA. (Email: firstname.lastname@example.org)
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Data presented (poster) at the Annual Meeting of Infectious Disease Society of America, 24-27 October 2002, Chicago, IL, and 51st Annual Epidemic Intelligence Service Conference, 22-26 April 2002, Atlanta, GA, USA.