Response to a community wide outbreak of cryptosporidiosis associated with recreational water facilities: Implementation and assessment of control measures

During 2008, a large community-wide outbreak of cryptosporidiosis occurred in North Texas, primarily associated with transmission in aquatic facilities. The Dallas County Department of Health and Human Services (DCHHS) completed interviews from 548 laboratory-confirmed cases, and an additional 262 persons meeting criteria as probable cases. The average age of cases was 15.4 years, with 35.5% of cases under 5 years of age. The average duration of illness was 9.4 days, with an average incubation period of 6.1 days. The average reporting lag from onset of symptoms to receipt of report by DCHHS was 16 days. Case interviews were initiated within 2 working days of receipt of report, with education provided and additional case-finding elicited during the interview. Promptly following recognition of the outbreak in the County, health alerts, press releases and education materials were widely disseminated to medical providers, media and the public. Recommendations for community-wide hyperchlorination of aquatics facilities were also disseminated to pool operators. Following media outreach and control measures, significant declines in rates of new cases were demonstrated, even prior to scheduled seasonal pool closures. The percentage of cases who reported swimming during illness fell from 34% to 12% during the latter half of the outbreak. Post-outbreak surveys of environmental public health staff identified challenges and significant cost burdens to municipal health departments in implementing hyperchlorination recommendations. While the effectiveness of control measures could be demonstrated during this outbreak, the challenges and public health burden of the necessary response highlights the need for an emphasis on prevention.