Author
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HIGGINS, JAMES |
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Submitted to: Virginia Water Environment Association
Publication Type: Abstract Only Publication Acceptance Date: 10/24/2003 Publication Date: 11/12/2003 Citation: Higgins, J.A. 2003. Detection and molecular characterization of enteric pathogens in fresh water [Abstract]. Virginia Water Environment Association. p.2. Interpretive Summary: Technical Abstract: Fresh water can be an important vehicle for exposure to enteric pathogens, either through consumption or recreational use. Some pathogens, such as encysted protozoa (Cryptosporidium parvum and Giardia intestinalis) are resistant to inactivation via chlorination and thus present special challenges to water providers. We have been investigating the use of affordable and user-friendly methods for the detection of enteropathogenic E. coli (EPEC) and C. parvum oocysts and Giardia cysts. Detection of EPEC is accomplished by subjecting aliquots of overnight coliform enrichment cultures to DNA extraction with inexpensive Instagene® matrix, followed by polymerase chain reaction (PCR) for the tir gene, a marker for EPEC. This technique has been evaluated on stream water samples from a variety of locales in the metro Baltimore / DC area, from April 2002 to October 2003, and been shown to successfully detect EPEC amongst other coliforms, at a rate of >50% (n = >750 samples). For detection of C. parvum and Giardia in stream water, we are using a simple protocol involving centrifugation, DNA extraction, and nested PCR. While few oocysts have been detected in our study stream, cysts of Giardia are surprisingly prevalent and sequence analysis of the PCR products indicates that they belong to the Assemblage A and Assemblage B categories. We conclude that leaking septic tanks and / or discharges from treatment plants are responsible for the deposition of these protozoa into the stream water. |
