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DETECTION OF PROTOZOAN PARASITES IN SOURCE AND FINISHED WATER - 3RD EDITION ASM'S METHODS IN ENVIRONMENTAL MICROBIOLOGY
Citation:
SCHAEFER, F. W. DETECTION OF PROTOZOAN PARASITES IN SOURCE AND FINISHED WATER - 3RD EDITION ASM'S METHODS IN ENVIRONMENTAL MICROBIOLOGY. 3rd, Chapter 21, Ronald L. Crawford, Jay L. Garland, David A. Lipson, Aaron L. Mills, Linda D. Stetzenbach (ed.), Methods in Environmental Microbiology. American Society for Microbiology, Washington, DC, , 265-279, (2007).
Impact/Purpose:
1) Refine new, practical methods for the detection of CCL-related and emerging waterborne human protozoa.
2) Perform field tests of devices or methods that have been developed under this task.
3) Evaluate these methods or devices in a variety of water matrices and parasite concentrations.
This work in this task supports CCL2 and 3 and is expected to be completed by 9/07.
Description:
Protozoans are eukaryotic organisms which can live either a free-living or parasitic existence. Some free-living forms, under the right conditions, can become opportunistic parasites. Enteric pathogenic protozoans, like Giardia and Cryptosporidium, which are now known to be transmitted by water have been responsible for numerous waterborne outbreaks of gastroenteritis. The primary means for detection, since density levels in water are low, involves processing a large volume of water by filtration, extracting the particulates from the filter, concentrating the organisms from the particulates, and assaying for the pathogens. The most widely used method for detecting protozoans has been the indirect immunofluorescent assay. While Method 1623 has improved upon the utility of the immunofluorescent assays for Giardia and Cryptosporidium, the procedure is still labor intensive and highly dependent on the skill of the microscopist. Even with the improvements to date, this technique is known to have a number of deficiencies including false positives, inability to determine the viability and species of the detected organisms, and low average percent recovery of cysts and oocysts. Various attempts have been made to improve the immunofluorescent detection method. Rather than sampling by filtration and buoyant density centrifugation to purify the organisms, carbonate flocculation is reported to improve recoveries. PCR, cell culture, FACS, and solid phase cytometry are currently being evaluated as alternate test procedures. As each of these approaches is relatively new and much more research is needed, it remains to be seen whether they will be equal to or better than the current fluorescent assay procedure.