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DETECTION OF CRYPTOSPORIDIUM OOCYSTS IN WATER MATRICES
Citation:
Schaefer, F W. DETECTION OF CRYPTOSPORIDIUM OOCYSTS IN WATER MATRICES. Presented at Cryptosporidium: From Molecules to Disease, Fremantle, Western Australia, Australia, October 7-12, 2001.
Impact/Purpose:
1) Conduct laboratory evaluations of new methods for detection of protozoan parasites.
2) Determine the infective dose of parasitic protozoa to hosts given a variety of models that will assist in estimating the public health significance at various levels of occurrence.
The work in this task will support CCL2 and 3 and will be completed by 9/05.
Description:
Since the advent and recognition of waterborne outbreaks of cryptosporidiosis great effort has been expended on development of methods for detecting Cryptosporidium oocysts in water. Oocysts recovery rates using a method originally developed for detecting Giardia cysts ranged from 0 to 11% in seeded samples. The poor oocyst recovery was based on the fact that up to 60% of the seeded oocysts passed through the fiber filter. Method 1622 for Cryptosporidium was developed using off the shelf reagents and equipment in an attempt to improve on oocyst recovery. Even with these improvements, the recovery results for the Method 1622 are only on average around 38%. Besides undefined parameters in water matrices, a number of other factors, such as laboratory proficiency and commercial reagent and equipment quality, are now known to compromise Cryptosporidium oocyst recovery. Fluorescent in situ hybridization probes have been suggested as assay additions for speciation of detected oocysts and for providing an indication of viability. Cryptosporidium cell culture has also been suggested as a mechanism for determining viability and infectivity of detected oocysts. Sensitivity, specificity, and the correlation with animal infectivity must be established for these new methods. At this point these new approaches are just research methods and remain to be multi-laboratory validated.