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Abstract: Enterococci are used to evaluate the safety of beach waters and studies have identified beach sands as a source of these bacteria. In order to study and quantify the release of microbes from beach sediments, flow column systems were built to evaluate flow of pore water out of beach sediments. Results show a peak in enterococci (average of 10% of the total microbes in core) released from the sand core within one pore water volume followed by a marked decline to below detection. These results indicate that few enterococci are easily removed and that factors other than simple pore water flow control the release of the majority of enterococci within beach sediments. A significantly larger quantity and release of enterococci were observed in cores collected after a significant rain event suggesting the influx of fresh water can alter the release pattern as compared to cores with no antecedent rainfall. [Copyright &y& Elsevier]

Abstract: A model study was conducted to understand the influence of non-point sources including bather shedding, animal fecal sources, and near shore sand, as well as the impact of the environmental conditions, on the fate and transport of the indicator microbe, enterococci, at a subtropical recreational marine beach in South Florida. The model was based on an existing finite element hydrodynamic and transport model, with the addition of a first order microbe deactivation function due to solar radiation. Results showed that dog fecal events had a major transient impact (hundreds of Colony Forming Units/100 ml [CFU/100 ml]) on the enterococci concentration in a limited area within several hours, and could partially explain the high concentrations observed at the study beach. Enterococci released from beach sand during high tide caused mildly elevated concentration for a short period of time (ten to twenty of CFU/100 ml initially, reduced to 2 CFU/100 ml within 4 h during sunny weather) similar to the average baseline numbers observed at the beach. Bather shedding resulted in minimal impacts (less than 1 CFU/100 ml), even during crowded holiday weekends. In addition, weak current velocity near the beach shoreline was found to cause longer dwelling times for the elevated concentrations of enterococci, while solar deactivation was found to be a strong factor in reducing these microbial concentrations. [Copyright &y& Elsevier]

Background: Microbial water-quality indicators, in high concentrations in sewage, are used to determine whether water is safe for recreational purposes. Recently, the use of these indicators to regulate recreational water bodies, particularly in sub/tropical recreational marine waters without known sources of sewage, has been questioned. The objectives of this study were to evaluate the risk to humans from exposure to subtropical recreational marine waters with no known point source, and the possible relationship between microbe densities and reported symptoms in human subjects with random-exposure assignment and intensive individual microbial monitoring in this environment.Methods: A total of 1303 adult regular bathers were randomly assigned to bather and non-bather groups, with subsequent follow-up for reported illness, in conjunction with extensive environmental sampling of indicator organisms (enterococci).Results: Bathers were 1.76 times more likely to report gastrointestinal illness [95% confidence interval (CI) 0.94-3.30; P = 0.07]; 4.46 times more likely to report acute febrile respiratory illness (95% CI 0.99-20.90; P = 0.051) and 5.91 times more likely to report a skin illness (95% CI 2.76-12.63; P < 0.0001) relative to non-bathers. Evidence of a dose-response relationship was found between skin illnesses and increasing enterococci exposure among bathers [1.46 times (95% CI 0.97-2.21; P = 0.07) per increasing log(10) unit of enterococci exposure], but not for gastrointestinal or respiratory illnesses.Conclusions: This study indicated that bathers may be at increased risk of several illnesses relative to non-bathers, even in the absence of any known source of domestic sewage impacting the recreational marine waters. There was no dose-response relationship between gastroenteritis and increasing exposure to enterococci, even though many current water-monitoring standards use gastroenteritis as the major outcome illness. [ABSTRACT FROM AUTHOR]