Author: Shun Yan Gladys Chong
Chong, Shun Yan Gladys, 2024 Investigation on the efficacy of UV disinfection on Cryptosporidium in swimming pools and other recreational water facilities, Flinders University, College of Science and Engineering
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Cryptosporidiosis outbreaks in swimming pools and other recreational water facilities, primarily caused by Cryptosporidium parvum and Cryptosporidium hominis, are responsible for most waterborn gastroenteritis cases in Australia. Cryptosporidium oocysts are notorious for their high tolerance to chlorination, allowing them to survive in well-maintained swimming pools for prolonged periods, posing a significant public health risk to swimmers. As of 1 September 2024, the number of cryptosporidiosis notifications from the National Notification Diseases Surveillance System (NNDSS) indicated a significant increase of confirmed cases in Queensland, New South Wales, and Victoria, implying an ongoing endemic outbreak. Research demonstrated that UV disinfection was effective in inactivating Cryptosporidium oocysts in drinking water treatment and wastewater treatment. However, it remains uncertain if ultraviolet light could eliminate the Cryptosporidium oocysts in swimming pools and other recreational water facilities. A comprehensive systematic literature review was conducted to identify eligible literature before 08 March 2024 and found that recreational water facilities with chlorine-based disinfectants along with UV disinfection in other countries had cryptosporidiosis outbreaks. It is suggested that more scientific studies be conducted to fill any knowledge gaps. Experiments were also carried out at four swimming pools in South Australia that used primary chlorination and secondary UV disinfection. Negative results of Colilert 18 testing were observed, suggesting primary chlorination with secondary UV disinfection was effective in eliminating E.coli. However, it was still unclear whether secondary UV disinfection with primary chlorination could eradicate Cryptosporidium oocysts efficiently. Future research using the reliable surrogate indicator is suggested for detecting Cryptosporidium oocysts in a swimming pool with secondary UV disinfection combined with primary chlorine disinfection. As there is no available vaccination and limited approved drug for treating cryptosporidiosis in immunocompromised adults, prevention of cryptosporidiosis greatly relies on the environmental health approach. It is essential to emphasise healthy swimmer practices and good hand hygiene. An extensive comparison of legislation, regulations, and guidelines related to cryptosporidiosis outbreaks in swimming pools and other recreational water facilities was undertaken. The findings indicated an inconsistency in the management of cryptosporidiosis outbreaks in recreational water facilities across Australia, particularly in the definitions for a cryptosporidiosis outbreak, guidelines related to CT value for hyperchlorination, recommendation for filter size and filtrate turbidity, recommendation for using UV as secondary disinfection, regular shock chlorine treatment in pools, and the legislative controls on using chlorine or bromine as primary disinfection and the recommendation for new high-risk public swimming pools. It is recommended that a National Recreational Water Facilities Standard And Guideline be established to provide a proper legal protocol for recreational water facility operators and staff, health authorities, and the swimming pool industry, for supervising and monitoring the remedial actions to prevent a cryptosporidiosis outbreak. The guideline should provide daily operational requirements for a recreational water facility to minimise public health risks.
Keywords: Cryptosporidiosis outbreaks, Cryptosporidium, Cryptosporidium oocysts, Cryptosporidium parvum, Cryptosporidium hominis, UV disinfection, swimming pool, recreational facility, aquatic facility, secondary disinfection in swimming pool, cryptosporidiosis notifications, National Notification Diseases Surveillance System, ultraviolet light disinfection, UV wavelength, superchlorination, hyperchlorination in swimming pool, CT value for hyperchlorination, remedial actions for Cryptosporidiosis outbreak in swimming pool, swimming pool legislations, swimming pool regulations, guideline for swimming pool, KAP for swimming pool operators, Environmental Health Officers, systemic literature review
Subject: Environmental Health thesis
Thesis type: Masters
Completed: 2024
School: College of Science and Engineering
Supervisor: Professor Kirstin Ross