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RESULTS FROM THE 2005 NATIONAL BEACHES STUDY: THE ASSOCIATION BETWEEN RAPIDLY MEASURED INDICATORS OF FECAL CONTAMINATION AND SWIMMING ASSOCIATED GASTROENTERITIS
Citation:
WADE, T. J., R. L. CALDERON, E. A. SAMS, K. P. BRENNER, M. BEACH, A. H. WILLIAMS, AND A. P. DUFOUR. RESULTS FROM THE 2005 NATIONAL BEACHES STUDY: THE ASSOCIATION BETWEEN RAPIDLY MEASURED INDICATORS OF FECAL CONTAMINATION AND SWIMMING ASSOCIATED GASTROENTERITIS. Presented at EPA Science Fourm, Washington, DC, May 16 - 18, 2005.
Description:
In 2003, the US EPA Office of Research and Development conducted studies at two Great Lakes beaches to evaluate the association between novel, rapid methods of measuring fecal contamination and swimming associated health effects. These results were presented at the 2004 Science Forum. In 2004, we conducted studies at two additional Great Lakes beaches. In these studies, swimming and non swimming beach goers are enrolled at the beach, and are telephoned to ascertain the occurrence of health symptoms 10-12 days after the beach visit. Water samples are collected from several fixed transects perpendicular to the beach three times a day. Swimmers are assigned exposure values based on the measures of water quality on the day, and/or time, and/or location of their reported swimming. Water samples are tested for indicators of fecal contamination (Enterococci, Bacteroides) using quantitative polymerase chain reaction (QPCR), a test that can be completed in under two hours. The beaches we studied in 2004, Silver Beach and Washington Park Beach, were both located on Lake Michigan and within 60 miles of each other. Combined, data were available for a total of approximately 15,000 subjects. At each beach, the incidence of gastrointestinal illness was higher among swimmers compared to non-swimmers. Daily and swimming-location specific averages of Enterococci measured by QPCR was significantly associated with gastrointestinal illness among swimmers at Washington Park Beach; and swimming-location specific averages of Enterococci measured by QPCR was significantly associated with gastrointestinal illness among swimmers at Silver Beach. Bacteroides results were difficult to interpret due to a high proportion of measures below the limit of detection. These results are consistent with the results observed in 2003 and indicate promise for the further use of QPCR as a rapid method to evaluate fecal contamination in fresh waters.