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Cryptosporidium parvum is now recognised as being responsible for around 2% of gastroenteritis cases in the immunocompetent population in developed nations, as well as being a significant cause of morbidity in immunocompromised hosts with depressed T-cell function. The resistance of Cryptosporidium oocysts to chlorine-based disinfectants creates particular concerns for drinking water supplies, and numerous outbreaks of cryptosporidiosis have been recorded from both drinking water and recreational water sources in parts of Europe and North America. In Australia, there have been a number of swimming pool-associated outbreaks of cryptosporidiosis, and only one drinking water outbreak from a small private water supply has been documented. Two genotypes of Cryptosporidium parvum have been identified as the major cause of infections in immunocompetent humans. Genotype 1 (or H), appears to infect humans specifically, whereas genotype 2 (or C) may infect humans and a range of other mammals (including cattle, sheep and goats). Species other than C. parvum have been reported to be responsible for up to 20% of infections in immunocompromised hosts, and there is emerging evidence that such species are also responsible for a minority of infections in the immunocompetent human population. We carried out case-control studies of cryptosporidiosis in Melbourne (with high quality source water treated by chlorination only) and Adelaide (with poor quality source water treated by conventional flocculation, sedimentation, filtration and chlorination). The results indicated that drinking tap water was not a significant risk factor for cryptosporidiosis in either city, but that person-to-person transmission and public swimming pools were the main sources of public health risk. Cryptosporidium isolates from participants in the Adelaide case-control study were characterised genetically using single strand conformation polymorphism analysis of the small subunit gene (pSSU; ∼300bp) and second internal transcribed spacer (pITS-2; 230bp) of nuclear ribosomal DNA. Of 26 isolates characterised to date, 15 (58%) were identified as C. parvum genotype 1, 9 (35%) were C. parvum genotype 2 and 2 (7.5%) were C. meleagridis. Neither of the people infected with C. meleagridis had reported any illness or condition affecting the immune system when interviewed for the case-control study. These results support observations from Europe that a small proportion of Cryptosporidium infections in immunocompetent people are caused by species other than C. parvum, in particular C. meleagridis. Acknowledgment: This work was funded by the CRC for Water Quality and Treatment, the Water Services Association of Australia, Melbourne Water Corporation, City West Water Ltd, South East Water Ltd and Yarra Valley Water Ltd. [ABSTRACT FROM AUTHOR]

Background: Community-based recruitment is challenging particularly if the sampling frame is not easily defined as in the case of people who drink rainwater. Strategies for contacting participants must be carefully considered to maximise generalisability and minimise bias of the results. This paper assesses the recruitment strategies for a 1-year double-blinded randomised trial on drinking untreated rainwater. The effectiveness of the recruitment strategies and associated costs are described., Methods: Community recruitment of households from Adelaide, Australia occurred from February to July 2007 using four methods: electoral roll mail-out, approaches to schools and community groups, newspaper advertising, and other media involvement. Word of mouth communication was also assessed., Results: A total of 810 callers were screened, with 53.5% eligible. Of those who were eligible and sent further information, 76.7% were willing to participate in the study and 75.1% were enrolled. The target for recruitment was 300 households, and this was achieved. The mail-out was the most effective method with respect to number of households randomised, while recruitment via schools had the highest yield (57.3%) and was the most cost effective when considering cost per household randomised (AUD$147.20). Yield and cost effectiveness were lowest for media advertising., Conclusion: The use of electoral roll mail-out and advertising via schools were effective in reaching households using untreated rainwater for drinking. Employing multiple strategies enabled success in achieving the recruitment target. In countries where electoral roll extracts are available to researchers, this method is likely to have a high yield for recruitment into community-based epidemiological studies.

A growing list of water contaminants has led to some water suppliers relying primarily on compliance monitoring as a mechanism for managing drinking water quality. While such monitoring is a necessary part of drinking water quality management, experiences with waterborne disease threats and outbreaks have shown that compliance monitoring for numerical limits is not, in itself, sufficient to guarantee the safety and quality of drinking water supplies. To address these issues, the Australian National Health and Medical Research Council (NHMRC) has developed a Framework for Management of Drinking Water Quality (the Framework) for incorporation in the Australian Drinking Water Guidelines, the primary reference on drinking water quality in Australia. The Framework was developed specifically for drinking water supplies and provides a comprehensive and preventive risk management approach from catchment to consumer. It includes holistic guidance on a range of issues considered good practice for system management. The Framework addresses four key areas: Commitment to Drinking Water Quality Management, System Analysis and System Management, Supporting Requirements, and Review. The Framework represents a significantly enhanced approach to the management and regulation of drinking water quality and offers a flexible and proactive means of optimising drinking water quality and protecting public health. Rather than the primary reliance on compliance monitoring, the Framework emphasises prevention, the importance of risk assessment, maintaining the integrity of water supply systems and application of multiple barriers to assure protection of public health. Development of the Framework was undertaken in collaboration with the water industry, regulators and other stakeholder, and will promote a common and unified approach to drinking water quality management throughout Australia. The Framework has attracted international interest.