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CONCENTRATION AND DETECTION OF CRYPTOSPORIDIUM OOCYSTS IN SURFACE WATER SAMPLES BY METHOD 1622 USING ULTRAFILTRATION AND CAPSULE FILTRATION
Citation:
Simmons, O. D., M. D. Sobsey, C. D. Heaney, F W. Schaefer, AND D. S. Francy. CONCENTRATION AND DETECTION OF CRYPTOSPORIDIUM OOCYSTS IN SURFACE WATER SAMPLES BY METHOD 1622 USING ULTRAFILTRATION AND CAPSULE FILTRATION. 2001, APPLIED AND ENVIRONMENTAL MICROBIOLOGY 67(3):1123-1127, (2001).
Impact/Purpose:
1) Refine new molecular and antibody labeling method for the detection of Giardia and Cryptosporidium in water.
2) Determine the occurrence and distribution of Giardia and Cryptosporidium in water supplies
Description:
The protozoan parasite cryptosporidium parvum is known to occur widely in both source and drinking water and has caused waterborne outbreaks of gastroenteritis. To improve monitoring, the USEPA developed Method 1622 for isolation and detection of cryptosporidim oocysts in water. Method 1622 is performance-based and involves filtration, concentration, immunomagnetic separation, fluorescent antibody and 4',6-diamidino-2-penylindole (DAPI) counter staining and microscopic evaluation. The capsule filter system currently recommended for Method 1622 was compared to a hollow fiber ultrafilter system for primary concentration of C. parvum oocysts in seeded reagent water and untreated surface waters. Samples were otherwise processed acccording to Method 1622. Cryptosporidium parvum oocyst recoveries from seeded 10-liter volumes of reagent water in precision and recovery experiments with filter pairs were 42% (S.D.=24%) and 46% (S.D.=18%) for hollow fiber ultrafilters and capsule filters, respectively. Mean oocyst recoveries in experiments testing both filters on seeded surface water samples were 42% (S.D.=27%) and 15% (S.D.=12%) for hollow fiber ultrafilters and capsule filters, respectively. Although C. parvum oocysts were recovered from surface waters using the approved filter of Method 1622, recoveries were significantly lower and more variable than from reagent grade water. In contrast, the disposable hollow fiber ultrafilter system was compatible with subsequent Method 1622 processing steps and recovered C. parvum oocysts from seeded surface waters with significantly greater efficiency and reliability than the currently approved filter.