Cryptosporidium source tracking in the potomac river watershed

Wenli Yang, Plato Chen, Eric N. Villegas, Ronald B. Landy, Charles Kanetsky, Vitaliano Cama, Theresa Dearen, Cherie L. Schultz, Kenneth G. Orndorff, Gregory J. Prelewicz, Miranda H. Brown, Roy Young Kim, Lihua Xiao

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


To better characterize Cryptosporidium in the Potomac River watershed, a PCR-based genotyping tool was used to analyze 64 base flow and 28 storm flow samples from five sites in the watershed. These sites included two water treatment plant intakes, as well as three upstream sites, each associated with a different type of land use. The uses, including urban wastewater, agricultural (cattle) wastewater, and wildlife, posed different risks in terms of the potential contribution of Cryptosporidium oocysts to the source water. Cryptosporidium was detected in 27 base flow water samples and 23 storm flow water samples. The most frequently detected species was C. andersoni (detected in 41 samples), while 14 other species or genotypes, almost all wildlife associated, were occasionally detected. The two common human-pathogenic species, C. hominis and C. parvum, were not detected. Although C. andersoni was common at all four sites influenced by agriculture, it was largely absent at the urban wastewater site. There were very few positive samples as determined by Environmental Protection Agency method 1623 at any site; only 8 of 90 samples analyzed (9%) were positive for Cryptosporidium as determined by microscopy. The genotyping results suggest that many of the Cryptosporidium oocysts in the water treatment plant source waters were from old calves and adult cattle and might not pose a significant risk to human health.

Original languageEnglish (US)
Pages (from-to)6495-6504
Number of pages10
JournalApplied and Environmental Microbiology
Issue number21
StatePublished - Nov 2008
Externally publishedYes

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Food Science
  • Biotechnology
  • Ecology


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