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GENOTYPING CRYPTOSPORIDIUM OOCYSTS IN WATER SAMPLES AS A TOOL FOR THE IDENTIFICATION OF CONTAMINATION SOURCES
Citation:
Xiao, L., J. Limor, A. Lal, K. Alderisio, A. Singh, T. Graczyk, AND M D. Royer*. GENOTYPING CRYPTOSPORIDIUM OOCYSTS IN WATER SAMPLES AS A TOOL FOR THE IDENTIFICATION OF CONTAMINATION SOURCES. Presented at AWWA Water Quality Technology Conference (WQTC), Salt Lake City, Ut, 11/5-9/00.
Description:
The identification of Cryptosporidium oocysts in environmental samples is largely made by the use of an immunofluorescent assay (IFA). Because IFA detects oocysts from all Cryptosporidium parasites, the species distribution and source of Cryptosporidium parasites in environmental samples is unclear. We previously developed a small subunit (SSU) rRNA-based polymerase chain reaction-restricution enzyme length polymorphism (PCR-RFLP) technique for species- and strin-specific diagnosis of Cryptosporidium parasites in clinical samples. In this study, we used this technique in conjunction with immunomagnetic separation to identify species and sources of Cryptosporidium oocysts present in water samples. Analysis of 25 stormwater samples collected after seven rain events with this technique revealed the presence of Cryptosporidium oocysts in 24 samples. A total of 11 wildlife Cryptosporidium genotypes were found in these samples, four of which were identified to species and sources by sequence analysis. In contrast, analysis of 22 surface water samples identified three common genotypes (the human and bovine genotypes of C. parvum and the bovine genotype of C. muris) in nine samples. Mixed genotypes were present in some storm and surface water samples. The SSU rRNA-based PCR-RFLP had the sensitivity and specificity required for the detection and differentiation of Cryptosporidium parasites in environmental samples, thus should be useful in the investigation of the identity and source of Cryptosporidium oocysts in source waters.