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IDENTIFICATION OF SPECIES AND SOURCES OF CRYPTOSPORIDIUM OOCYSTS IN STORM WATERS BY A SMALL SUBUNIT RRNA-BASED DIAGNOSTIC AND GENOTYPING TOOL
Citation:
Xiao, L., J. Limor, A. Lal, K. Alderisio, AND M D. Royer*. IDENTIFICATION OF SPECIES AND SOURCES OF CRYPTOSPORIDIUM OOCYSTS IN STORM WATERS BY A SMALL SUBUNIT RRNA-BASED DIAGNOSTIC AND GENOTYPING TOOL. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. American Society for Microbiology, Washington, DC, 66(12):5492-5498, (2000).
Description:
The identification of Cryptosporidium oocysts in environmental samples is largely made by the use of immunofluorescent assay (IFA). because IFA detects oocysts from all Cryptosporidium parasites, the species distribution and source of Cryptosporidium parasites in environmental samples cannot be delineated. We developed a small subunit (SSU) rRNA-based PCR-RFLP technique for species-and strain-specific diagnosis of Cryptosporidium parasites in clinical samples, and found the presence of host-adapted Cryptosporidium parasites. In this study, we have used this technique in conjunction with immunomagnetic separation to identify species and sources of Cryptosporidium oocysts present in storm water samples collected from a stream within the New York City water supply system. Analysis of 25 storm samples collected after seven rain events with this technique revealed the presence of Cryptosporidium oocysts in 24 samples, including several that were negative by Percoll-sucrose floatation and microscopic examinations. A total of 11 genotypes were found, 4 of which were identified to species and sources by sequence analysis, whereas the rest represent new genotypes from wildlife. The SSU rRNA-based PCR-RFLP had the sensitivity and specificity required for the detection and differentiation of Cryptosporidium parasites in environmental samples, thus it should be useful in the investigation of the identity and source of Cryptosporidium oocysts in source waters.