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Applied and Environmental Microbiology, November 2008, p. 6495-6504, Vol. 74, No. 21
0099-2240/08/$08.00+0 doi:10.1128/AEM.01345-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Cryptosporidium Source Tracking in the Potomac River Watershed
Wenli Yang,1
Plato Chen,2
Eric N. Villegas,3
Ronald B. Landy,4
Charles Kanetsky,4
Vitaliano Cama,1
Theresa Dearen,1
Cherie L. Schultz,5
Kenneth G. Orndorff,6
Gregory J. Prelewicz,7
Miranda H. Brown,8
Kim Roy Young,4 and
Lihua Xiao1*
Centers for Disease Control and Prevention, Atlanta, Georgia 30341,1 Washington Suburban Sanitary Commission, Laurel, Maryland 20705,2 National Exposure Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 452683,3 EPA Region III, Fort Meade, Maryland 20755,4 Interstate Commission for the Potomac River Basin, Rockville, Maryland 20850,5 Frederick County Division of Utilities and Solid Waste Management, Frederick, Maryland 21704,6 Fairfax Water, Fairfax, Virginia 22031,7 Washington Aqueduct, Washington, DC 200168
Received 16 June 2008/ Accepted 22 August 2008
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.
* Corresponding author. Mailing address: Division of Parasitic Disease, National Center for Infectious Disease, Centers for Disease Control and Prevention, Building 22, Mail Stop F-12, 4770 Buford Highway, Atlanta, GA 30341-3717. Phone: (770) 488-4840. Fax: (770) 488-4454. E-mail: lxiao{at}cdc.gov
Published ahead of print on 5 September 2008.
Applied and Environmental Microbiology, November 2008, p. 6495-6504, Vol. 74, No. 21
0099-2240/08/$08.00+0 doi:10.1128/AEM.01345-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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