Standard methods to measure recreational water quality require at least 24 hr to obtain results, making it impossible to assess the quality of water within a single day. Methods to measure recreational water quality in ≤ 2 hr have been developed. Application of rapid methods could give considerably more accurate and timely assessments of recreational water quality. We conducted a prospective study of beachgoers at two Great Lakes beaches to examine the association between recreational water quality, obtained using rapid methods, and gastrointestinal (GI) illness after swimming. Beachgoers were asked about swimming and other beach activities and 10–12 days later were asked about the occurrence of GI symptoms. We tested water samples for Enterococcus and Bacteroides species using the quantitative polymerase chain reaction (PCR) method. We observed significant trends between increased GI illness and Enterococcus at the Lake Michigan beach and a positive trend for Enterococcus at the Lake Erie beach. The association remained significant for Enterococcus when the two beaches were combined. We observed a positive trend for Bacteroides at the Lake Erie beach, but no trend was observed at the Lake Michigan beach. Enterococcus samples collected at 0800 hr were predictive of GI illness that day. The association between Enterococcus and illness strengthened as time spent swimming in the water increased. This is the first study to show that water quality measured by rapid methods can predict swimming-associated health effects.

Since the 1950s, numerous studies have examined the association between recreational water quality and health outcomes. Many of these studies have reported an increased risk of illness associated with exposure to recreational water. Several have related the level of contamination in the water, as measured by indicators of water quality, with the magnitude of risk. Despite extensive research on this topic, uncertainty remains about how water quality indicators can best be used in the regulation of recreational water environments. In 1986, the U.S. Environmental Protection Agency (U.S. EPA 1986) published recommended water quality criteria for recreational waters, which proposed the use of enterococci in marine water and enterococci and/or Escherichia coli in fresh water as indicator organisms. That report recommended regulatory levels based on geometric means of at least five samples over a 30-day period of 35 colony-forming units (cfu)/100 mL and 33 cfu/100 mL for enterococci in marine and fresh water, respectively; and 126 cfu/100 mL for E. coli in fresh water (U.S. EPA 1986). Fecal coliforms, which had been previously proposed for use as an indicator, were no longer recommended. The studies upon which these revised guidelines were based (Cabelli 1983;Dufour 1984a) have been criticized (Fleisher 1992), and the draft revised World Health Organization (2001) guidelines have been developed using more recent controlled studies ).Few attempts have been made to summarize and evaluate the existing literature in a systematic and quantitative framework. Pruss (1998) concluded that the literature strongly suggests a dose-response relationship between fecal contamination and the risk of gastrointestinal (GI) illness but did not examine the relationship between specific water quality indicators and health outcomes.Our primary goal in this systematic review was to evaluate the evidence linking specific microbial indicators of recreational water quality to specific health outcomes under nonoutbreak conditions. Secondary goals were to identify and describe critical study design issues, to quantify and evaluate sources of heterogeneity among the studies, and to evaluate the potential for health effects at or below the current suggested regulatory standards. MethodsLiterature search. Our literature search included several computerized databases: MEDLINE (http://www.ncbi.nlm.nih.gov/ entrez/query.fcgi?db=PubMed), BIOSIS (www.biosis.org), OLDMEDLINE (http:// gateway.nlm.nih.gov/gw/Cmd), and EMBASE (http://openaccess.dialog.com/med/) for the period from 1950 to the present. We searched dissertations using the UMI/ProQuest Digital Dissertation Database (http://wwwlib.umi.com/ dissertations/gateway). The search terms included key words "recreational water and health" and subject heading searches for "environmental pollutants, adverse effects" or "water pollution, adverse effects." We consulted experts in the field and reviewed the bibliographies of relevant studies for additional references. We reviewed the titles and abstracts of a...

Traditional fecal indicators currently used to monitor these beaches were not associated with health risks. These results suggest a need for alternative indicators of water quality where nonpoint sources are dominant fecal contributors.

IntroductionIn the United States and elsewhere, recreational water quality is monitored for fecal indicator bacteria to help prevent swimming-associated illnesses. Standard methods to measure these bacteria take at least 24 hours to obtain results. Molecular approaches such as quantitative polymerase chain reaction (qPCR) can estimate these bacteria faster, in under 3 hours. Previously, we demonstrated that measurements of the fecal indicator bacteria Enterococcus using qPCR were associated with gastrointestinal (GI) illness among swimmers at freshwater beaches. In this paper, we report on results from three marine beach sites.MethodsWe interviewed beach-goers and collected water samples at marine beaches affected by treated sewage discharges in Mississippi in 2005, and Rhode Island and Alabama in 2007. Ten to twelve days later, we obtained information about gastrointestinal, respiratory, eye, ear and skin symptoms by telephone. We tested water samples for fecal indicator organisms using qPCR and other methods.ResultsWe enrolled 6,350 beach-goers. The occurrence of GI illness among swimmers was associated with a log10-increase in exposure to qPCR-determined estimates of fecal indicator organisms in the genus Enterococcus (AOR = 2.6, 95% CI 1.3-5.1) and order Bacteroidales (AOR = 1.9, 95% CI 1.3-2.9). Estimates of organisms related to Clostridium perfringens and a subgroup of organisms in the genus Bacteroides were also determined by qPCR in 2007, as was F+ coliphage, but relationships between these indicators and illness were not statistically significant.ConclusionsThis study provides the first evidence of a relationship between gastrointestinal illness and estimates of fecal indicator organisms determined by qPCR at marine beaches.

Measurement of the indicator bacteria Enterococci in recreational water using a rapid QPCR method predicted swimming-associated GI illness at freshwater beaches polluted by sewage discharge. Children at 10 years or younger were at greater risk for GI illness following exposure.

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