Cryptosporidium and Giardia were characterized in a watershed in southern Ontario, Canada, over a 2½ year period. River samples were collected every two weeks, primarily near a municipal drinking water treatment plant intake. Cryptosporidium and Giardia were frequently detected with an overall occurrence rate of 88 and 97%, respectively. Giardia concentrations were higher than Cryptosporidium, with median values of 80 cysts 100 L−1 and 12 oocysts 100 L−1, respectively. Although pathogens rarely show a significant relationship with fecal or water quality indicators, this study determined that Cryptosporidium, but not Giardia, was significantly correlated with Escherichia coli, turbidity and river flow. There was no correlation between the two types of protozoa, and only Giardia showed a seasonal trend with higher concentrations at cold water temperatures. Cryptosporidium genotyping of all samples found that farm animals and wildlife were an important contributor of oocysts in the watershed, and that Cryptosporidium strains/genotypes of medium to high risk for human infection (C. hominis, C. parvum and C. ubiquitum) were detected in 16% of samples. This study was able to identify Cryptosporidium host sources and human health risk, and to identify differences between Cryptosporidium and Giardia occurrence in the watershed.
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Research Article|
March 08 2012
Identifying host sources, human health risk and indicators of Cryptosporidium and Giardia in a Canadian watershed influenced by urban and rural activities
Michele I. Van Dyke;
1NSERC Chair in Water Treatment, Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
E-mail: [email protected]
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Corinne S. L. Ong;
Corinne S. L. Ong
2British Columbia Centre for Disease Control Public Health Microbiology and Reference Laboratories, Vancouver, British Columbia, Canada
3Department of Laboratory Medicine and Pathology, University of British Columbia, Vancouver, British Columbia, Canada
*Present address: School of Occupational & Public Health, Ryerson University, Toronto, Ontario, Canada
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Natalie A. Prystajecky;
Natalie A. Prystajecky
2British Columbia Centre for Disease Control Public Health Microbiology and Reference Laboratories, Vancouver, British Columbia, Canada
3Department of Laboratory Medicine and Pathology, University of British Columbia, Vancouver, British Columbia, Canada
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Judith L. Isaac-Renton;
Judith L. Isaac-Renton
2British Columbia Centre for Disease Control Public Health Microbiology and Reference Laboratories, Vancouver, British Columbia, Canada
3Department of Laboratory Medicine and Pathology, University of British Columbia, Vancouver, British Columbia, Canada
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Peter M. Huck
Peter M. Huck
1NSERC Chair in Water Treatment, Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
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J Water Health (2012) 10 (2): 311–323.
Article history
Received:
August 12 2011
Accepted:
January 15 2012
Citation
Michele I. Van Dyke, Corinne S. L. Ong, Natalie A. Prystajecky, Judith L. Isaac-Renton, Peter M. Huck; Identifying host sources, human health risk and indicators of Cryptosporidium and Giardia in a Canadian watershed influenced by urban and rural activities. J Water Health 1 June 2012; 10 (2): 311–323. doi: https://doi.org/10.2166/wh.2012.131
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