Proactive Surveillance of Public Swimming Pools to Prevent Delayed Detection of Cryptosporidiosis Outbreaks

Swimming pool-related cryptosporidiosis outbreaks are a global issue disproportionately affecting young children. This study aimed to (1) quantify swimming pool outbreak detection timelines; (2) identify pathogen prevention and detection strategies from Australia, United Kingdom, United States, and World Health Organization guidelines for public swimming pools; and (3) review oocyst detection methods used in pool-related cryptosporidiosis investigations.

Literature searches of peer-reviewed databases, public health publications, and relevant government guideline repositories were conducted. The interval between pool contamination, outbreak detection, and disinfection was estimated using an average response scenario. A comparative analysis of pool guidelines was performed based on Cryptosporidium prevention and testing strategies. Efficacy of proactive and reactive testing was estimated using oocyst detection yields from global studies.

There was an average delay of 27 days between pool contamination and disinfection, contributing to the persistence of outbreaks in swimming pools. Cryptosporidium prevention strategies varied and were inconsistent across jurisdictions. Proactive surveillance was discouraged in many jurisdictions based on financial cost, methodological gaps, and sampling biases. Oocyst detection data showed a proactive approach provides surveillance and prevalence metrics in aquatic facilities.

Reliance on notification-based outbreak identification and existing contamination prevention guidelines appear insufficient to prevent and reduce outbreaks in public swimming pools. Barriers to proactive surveillance can be addressed by monitoring high-risk settings using existing methods alongside current mandatory microbiological surveillance already occurring in swimming pools. Earlier detection of contamination events would significantly reduce pool-associated cryptosporidiosis outbreaks locally and globally, and reduce the burden of gastroenteric disease in young children.