AWWA WQTC58937

To assess the source and public health significance of Cryptosporidium oocyst contamination in storm water, a PCR-RFLP technique based on the small subunit rRNA gene was used in the analysis of 40 storm water samples collected from the Malcolm Brook, New York over a one year period. The distribution of Cryptosporidium spp. and genotypes in storm water samples collected in this study was compared with the data obtained from 29 storm water samples from the Ashokan Brook in a previous study. Most storm water samples (59 of 69) from both watersheds were positive for Cryptosporidium oocysts by PCR, almost all of which belonged to species and genotypes that have not been previously detected in humans or domestic animals. Of the 59 PCR positive samples analyzed from both watersheds, 54 (91.5%) were linked to either known or unknown animal sources. In addition, C. hominis (W14 genotype) was detected in several samples collected from the Malcolm Brook over a two-week period. Several Cryptosporidium spp. were commonly found in both watersheds, including W4 (cervid) genotype from deer, W7 (muskrat) genotype from muskrats, W11 (snake) genotype from 1snakes, and W1 genotype from an unknown animal source (possibly rodents). Several Cryptosporidium spp. commonly seen in the Ashokan Brook, such as W10 genotype (C. baileyi) from birds, W2 (opossum genotype I) and W8 (opossum genotype II) from opossums, and W6 from unknown animals, were not detected in samples from Malcolm Brook. Likewise, several wildlife genotypes commonly seen in Malcolm Brook were not seen in samples from Ashokan Brook, such as W15 (animal source unknown), W16 (possibly a fox parasite), and W17 (possibly a rodent parasite). Altogether, 18 Cryptosporidium parasites were found in storm water samples from these watersheds, only 12 of which could be attributed to known species/groups of animals. Aliquots of 37 samples from the Malcolm Brook were also analyzed by EPA Method 1623; 16 of the samples were positive by microscopy, with 1-4 oocysts per aliquot. In contrast, all microscopy-positive and 13 of the 21 microscopy-negative samples were positive by PCR. Results of the study indicate that molecular techniques can complement traditional detection methods by providing information on the source of contamination and human-infective potential of Cryptosporidium oocysts found in water. Includes 32 references, tables, figures.