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A Historical Perspective of Detection Methods for Giardia Cysts and Cryptosporidium Oocysts in Water

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Abstract:In the mid-20th century Giardia was classified as a non-pathogenic commensal organism and Cryptosporidium was not recognized yet. However as early as 1946 a waterborne outbreak of giardiasis was suspected. From 1965 to 1979 it became clear that Giardia lamblia was indeed a human pathoge and was responsible for waterborne gastroenteritis. Unlike bacteria, there are no simple culture methods for enteric protozoan parasites, so detection and identification were limited to microscopic observations. Because the densities of cysts and oocysts in water often can be less than one per liter, volumes between 10 and 1,000 liters must be examined. The initial sampling approach of the Centers for Disease Control and Prevention was to use a sand filter on a flatbed truck, while that of the U.S.EPA was to use a fiber wound cartridge filter which became the standard. Buoyant density flotation protocols employing zinc sulfate, sucrose, Percoll, and Percoll-sucrose have been used to purify and further concentrate the cysts and oocysts. Percoll-sucrose eventually became the standard flotation medium.
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Citation:Schaefer, F. W. A Historical Perspective of Detection Methods for Giardia Cysts and Cryptosporidium Oocysts in Water. Presented at USGS Workshop "Building Capabilities for Monitoring & Assessment of Public Health Microbiology", Columbus, OH, March 13-14, 2000.
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Contact: Mary P. O'Bryant - (919)-541-4871 or obriant.mary@epa.gov
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Division: Microbiological & Chemical Exposure Assessment Division
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Branch: Biohazard Assessment Research Branch
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Product Type: Abstrct/Oral
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Presented: 03/14/2000
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Related Entries:
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Bullet Item Detecting Ccl-Related, Emerging and Regulated Waterborne Human Protozoa for Exposure Assessment
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Last Updated on Monday, October 22, 2007
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