Comparison of the distribution of Cryptosporidium genotypes in storm water samples from two watersheds

摘要

To assess the source and public health significance of Cryptosporidium oocyst contamination inrnstorm water, a PCR-RFLP technique based on the small subunit rRNA gene was used in thernanalysis of 40 storm water samples collected from the Malcolm Brook, New York over onernyear period. The distribution of Cryptosporidium spp. And genotypes in storm water samplesrncollected in this study was compared with the data obtained from 29 storm water samples fromrnthe Ashokan Brook in a previous study. Most storm water samples (59 of 69) from bothrnwatersheds were positive for Cryptosporidium oocysts by PCR, almost all of which belonged tornspecies and genotypes that have not been previously detected in humans or domestic animals.rnOf the 59 PCR positive samples analyzed from both watersheds, 54 (91.5%) were linked torneither known or unknown animal sources. In addition, C. hominis (W14 genotype) was detectedrnin several samples collected from the Malcolm Brook over a two-week period. SeveralrnCryptosporidium spp. Were commonly found in both watersheds, including W4 (cervid)rngenotype from deer, W7 (muskrat) genotype from muskrats, W11 (snake) genotype fromrn1snakes, and W1 genotype from an unknown animal source (possibly rodents). SeveralrnCryptosporidium spp. Commonly seen in the Ashokan Brook, such as W10 genotype (C. baileyi)rnfrom birds, W2 (opossum genotype I) and W8 (opossum genotype II) from opossums, and W6rnfrom unknown animals, were not detected in samples from Malcolm Brook. Likewise, severalrnwildlife genotypes commonly seen in Malcolm Brook were not seen in samples from AshokanrnBrook, such as W15 (animal source unknown), W16 (possibly a fox parasite), and W17rn(possibly a rodent parasite). Altogether, 18 Cryptosporidium parasites were found in stormrnwater samples from these watersheds, only 12 of which could be attributed to knownrnspecies/groups of animals. Aliquots of 37 samples from the Malcolm Brook were also analyzedrnby EPA Method 1623; 16 of the samples were positive by microscopy, with 1-4 oocysts perrnaliquot. In contrast, all microscopy-positive and 13 of the 21 microscopy-negative samplesrnwere positive by PCR. Results of the study indicate that molecular techniques can complementrntraditional detection methods by providing information on the source of contamination and human-infective potential of Cryptosporidium oocysts found in water.