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COMPARISON OF MICROSCOPIC VERSUS MOLECULAR DIAGNOSIS OF CYCLOSPORA CAYETANENSIS
Citation:
Lindquist, H.D A., M Varma, M W. Ware, C. Aranzamendi, AND C. Vargas. COMPARISON OF MICROSCOPIC VERSUS MOLECULAR DIAGNOSIS OF CYCLOSPORA CAYETANENSIS. Presented at Joint meeting of the International Congress of Parasitology and Annual Meeting of the American Society of Parasitologists, Vancouver, British Columbia, Canada, August 4-10, 2002.
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:
Objective: to investigate several ways to diagnose the food and waterborne protozoan parasite Cyclospora cayetanensis. Cyclospora cayetanensis is a protozoan parasite that infects human beings and causes gastroenteritis. Diagnosis of this parasite is complicated by the fact that it is difficult to stain, or visualize through the techniques associated with typical ova and parasite examinations.
Materials and Methods: More than one hundred stools were collected from children in Lima Peru during the course of normal diagnostic and treatment activities. These stool samples were screened by standard ova and parasite evaluation. The remainder of those samples that were found to be positive for parasites were screened again, using fluorescent microscopy, to detect any autofluorescent parasites, which were then confirmed as to genus or presumptively to species using differential interference contrast microscopy. These results were recorded. Aliquots of samples were removed for analysis by taqman assay. This assay incorporates PCR using a dual labeled fluorescence probe designed to increase in fluorescence intensity as it is digested during a successful PCR.
Results: Results of this assay were compared to the results from microscopic examination of the specimens. It was found that both microscopic analysis and the PCR based assay were able to detect Cyclospora cayetanensis oocysts, while standard ova and parasite examination was not.
Conclusions: Standard ova and parasite examinations are not sufficient to detect this emerging infection. Both fluorescence microscopy and a PCR based method succeed in detecting this parasite when standard methods did not. The PCR based assay provided a quantitative capability, but the accuracy of this quantitation was not tested in this study.