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NEW MICROBIAL INDICATORS OF FECAL POLLUTION
Impact/Purpose:
The primary objective of this task is to identify, from a statistically significant pool of candidates, the fecal indicator microorganism(s) whose densities in recreational waters best correlate with the rates of illnesses monitored in the current health studies.
A second objective (pending the availability or development of suitable assays) will be to determine whether the rates of these illnesses are correlated with fecal pollution from humans or from various specific animal sources.
Description:
Recent legislation and EPA action plans, including the Clean Water Action Plan, the Beach Action Plan, and the Beach Act of 2000, have identified new requirements to protect recreational waters and people's health. To meet these requirements, a new health study (task 9656), conducted jointly by NERL and NHEERL, has been initiated to formulate new health and risk guidelines for recreational water using the new monitoring protocol developed in the EMPACT study and several newly developed rapid methods including real time, quantitative polymerase chain reaction (QPCR). The QPCR analyses in this study have thus far measured organisms in the genus Enterococcus, which were determined in an earlier EPA recreational water health study to provide the "best" correlations between the microbial indicators in both marine and fresh water and the health data (i.e., those linear relationships where gastrointestinal symptoms or illness rates increased as the water quality indicator densities increased), based on culture analysis. In addition, this effort has also used QPCR analyses on these samples (using the first iteration of an assay developed at Oregon State University) for potential indicator organisms in the genus Bacteroides.
A unique benefit of molecular based methods such as QPCR is that they should be able to provide valid occurrence data for any organisms collected from water samples in the current health study for which suitable assays later become available. This can be done by analyses of archived water filtrates from the study with these assays. In anticipation of this application, replicate filtrates of each of the water samples collected in the current ongoing EPA health study as well as a similar study being conducted by the Southern California Coastal Water Research Project (SCCWRP) are being preserved by freezing. Each of these samples will be associated with data on the rates of illnesses that may be attributable to recreational bathing on each day and time of sample collection. In addition, DNA sequence information is accumulating for a growing number of bacterial species that are known to occur in human and animal GI tracts at high concentrations and hence may serve as new indicators of fecal pollution in source and drinking waters as well as recreational waters. The majority of these organisms are not amenable to detection by culture based methods. This work is also moving towards the elucidation of nucleic acid sequence markers for organisms that are specific to the guts of humans and different types of animals. This may allow for the development of assays for specific sources of fecal pollution. These developments provide a unique opportunity to retrospectively assess relationships between the rates of illnesses reported by bathers in the health studies and the occurrence of a wide variety of new potential indicator organisms. They may also provide an opportunity to further explore the relationships between various defined sources of fecal pollution and health outcomes.