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Screening candidate water quality indicators for associations with swimming-related illness
Citation:
Colford, J. M., K. Schiff, B. Arnold, J. Griffith, C. Wright, M. Gold, C. McGee, V. Yau, T. J. WADE, AND S. Weisberg. Screening candidate water quality indicators for associations with swimming-related illness. Presented at BEACHES conference, Huntington Beach, CA, April 20 - 22, 2009.
Impact/Purpose:
research results
Description:
ABSTRACT Traditional (culture-based) indicator organisms (e.g. enterococci, fecal and total coliforms) are used to regulate marine beaches for protecting human health. Despite the recent proliferation of new technology, few studies have examined alternatives to this decades-old practice. The goal ofthis study was to evaluate a large number ofnew methods or candidate indicators for improved prediction ofpublic health risk at marine beaches. A prospective cohort epidemiologic study was conducted at two beaches (Avalon Bay and Doheny State Beach) in southern California during the summers of2007-08. Cumulatively, over 15,000 beachgoers were recruited and their health status evaluated for 20 different symptoms. In addition, nearly 40 different candidate water quality indicators were measured on the day of exposure including traditional indicators, rapid methods for traditional indicators, nontraditional indicators (i.e., microbial source tracking tools), and viruses. The strength of association between each indicator concentration and illness was evaluated using a logistic model that adjusted for differences in beachgoer characteristics (age, gender, racelethnicity and numerous other potentially confounding factors). Preliminary data analysis indicated no consistent association between traditional culture-based indicators and any ofthe 20 symptoms including highly credible gastrointestinal illness (HCGI). However, an association between enterococcus using quantitative polymerase chain reaction (qPCR) and HCGI was observed (adjusted odds ratio = 2.34,95% CI 1.24 -4.42) among single-day swimmers with body immersion at Avalon Beach in 2007. These date indicate that application of new technology could be used for monitoring at marine beaches.