Results Most studies reported a dose-related increase of health risk in swimmers with an increase in the indicator-bacteria count in recreational waters. Relative risk (RR) values for swimming in polluted water versus clean water were often significant (usually 1.0 < RR < 3.0). The indicator microorganisms that correlate best with health outcomes were enterococci/faecal streptococci for both marine and freshwater, and Escherichia colt for freshwater. In both marine and freshwater, increased risk of gastro-intest inal symptoms was reported for water quality values ranging from only a few indicator counts/100 ml to about 30 indicator counts/100 ml. These values are low compared with the water qualities frequently encountered in coastal recreational waters. Studies which showed a higher threshold for increased risk and case-rate values in some countries may suggest immunity due to endemicity or a lower pathogen-to-indicator ratio in the natural waters. Conclusions The review strongly suggests a causal dose-related relationship between gastrointestinal symptoms and recreational water quality measured by bacterial indicator counts.

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Review of epidemiological studies on health effects from exposure to recreational water

Despite numerous studies, uncertainty remains about how water quality indicators can best be used in the regulation of recreational water. We conducted a systematic review of this topic with the goal of quantifying the association between microbial indicators of recreational water quality and gastrointestinal (GI) illness. A secondary goal was to evaluate the potential for GI illness below current guidelines. We screened 976 potentially relevant studies and from these identified 27 studies. From the latter, we determined summary relative risks for GI illness in relation to water quality indicator density. Our results support the use of enterococci in marine water at U.S. Environmental Protection Agency guideline levels. In fresh water, (Italic)Escherichia(/Italic) coli was a more consistent predictor of GI illness than are enterococci and other bacterial indicators. A log (base 10) unit increase in enterococci was associated with a 1.34 [95% confidence intervals (CI), 1.00-1.75] increase in relative risk in marine waters, and a log (base 10) unit increase in E. coli was associated with a 2.12 (95% CI, 0.925-4.85) increase in relative risk in fresh water. Indicators of viral contamination were strong predictors of GI illness in both fresh and marine environments. Significant heterogeneity was noted among the studies. In our analysis of heterogeneity, studies that used a nonswimming control group, studies that focused on children, and studies of athletic or other recreational events found elevated relative risks. Future studies should focus on the ability of new, more rapid and specific microbial methods to predict health effects, and estimating the risks of recreational water exposure among susceptible persons.

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Do U.S. Environmental Protection Agency water quality guidelines for recreational waters prevent gastrointestinal illness? A systematic review and meta-analysis.

Urban Drainage: Impacts on Receiving Water Quality

Worldwide, the popularity of recreational activities which involve contact with water is continuing to grow. Moreover, ease of travel and change in human behaviour has altered the use of water for recreational purposes. Users should be aware that recreational exposures to pathogens may result in disease. Susceptible populations including people with reduced immune function (e.g., resulting from disease (cancer, HIV), genetic susceptibility, age, etc.) or lack of immunity to locally endemic diseases (e.g., tourists) may be at higher risk of contracting illnesses. In most cases the primary disease symptoms associated with recreational water contact are acute, such as diarrhoea and respiratory infections. Although less frequently reported, more serious and potentially fatal disease is a risk to recreational users of water especially in certain susceptible populations.

In addition to diseases which have severe primary outcomes (e.g., primary amoebic meningoencephalitis, typhoid, leptospirosis), a number of infections may lead to sequelae with serious consequences including renal disease (from E. coli O157:H7 for example), cardiac and nutritional disorders. This is the first book to provide a comprehensive review and analysis of potential severe disease outcomes, including acute effects and sequelae, associated with recreational water activities. This book will be useful to all those concerned with recreational water quality, including environmental and public health professionals, local authorities, user groups, and tourists.

Water Recreation and Disease sets out to identify the more severe waterborne diseases and their sequelae which may be acquired while undertaking water-based recreation in marine, freshwater, spas/whirlpools and swimming pools. The review systematically brings information together on the ecology and health aspects of a variety of pathogens where cases attributed to recreational use of water have been documented.

This is the only available guide to bring together information on the more severe waterborne diseases to assist decision-making in recreational water management.

This title belongs to WHO Emerging Issues in Water & Infectious Disease Series. .

ISBN: 9781780405827 (eBook)

ISBN: 9781843390664 (Print)

Water Recreation and Disease: Plausibility of Associated Infections: Acute Effects, Sequelae and Mortality

Human recreational exposure to antibiotic resistant bacteria in coastal bathing waters.

There are certain health risks associated with recreational exposure to bacteriologically polluted water. In this study, 27% (21/77) of swimmers who took part in a snorkel swimming event, experienced gastrointestinal symptoms within 48 hours of entering the untreated water. The incidence of these symptoms was statistically significantly greater than the incidence of such symptoms reported by two control populations (p less than 0.001), but not significantly different to 25% of people who had experienced gastrointestinal symptoms in a previous snorkel event in the same water environment. As the water quality came within the confidence intervals of the EEC standards for bathing water the adequacy of these standards needs further appraisal.

R G Enticott

Papers

Health Risks of Snorkel Swimming in Untreated Water