AWWA ACE58303

Waterborne transmission of the protozoan parasite Cryptosporidium parvum remains asignificant source of disease with severe consequences for immunocompromised people. Overthe past decade much progress has been made in addressing the issue of Cryptosporidium inwater. Both the Interim Enhanced Surface Water Treatment Rule (IESWTR) and the Long Term1 Enhanced Surface Water Treatment Rule (LT1ESWTR) were promulgated by the US Environmental Protection Agency (USEPA) toreduce the risk of cryptosporidiosis. The pending Long Term 2 Enhanced Surface WaterTreatment Rule (LT2ESWTR) will require additional treatment for utilities with poor sourcewater quality. In addition, many utilities, including all of the utility subsidiaries of AmericanWater, have joined a voluntary Partnership for Safe Drinking Water to further tighten operatingstandards to improve the treatment of Cryptosporidium oocysts.The immunofluorescent antibody (IFA) test has been used to detect Cryptosporidium oocysts infiltered drinking water but the assay has a number of limitations. The IFA assaycannot determine the public health significance of oocysts detected in drinking water. As aresult, American researchers developed a patented test for detecting live, infectiousCryptosporidium oocysts in water. The method called the "cell culture, polymerase chainreaction" (CC-PCR) test is accurate and precise because it measures the DNA ofCryptosporidium that are able to grow in human intestinal cells after the isolation of infectiousoocysts from water samples.Application of the CC-PCR assay to filtered drinking water samples can help determine thecentral question facing water utilities: do current water treatment techniques adequatelycontrol the risks of Cryptosporidium in water? The current study was initiated to answer thisquestion and provide a strategy for control of Cryptosporidium in water. Monthly finished plant effluent samples were collected from 82 conventional surface watertreatment plants, located in 14 states, for a total of 1690 100-L finished water samples analyzedby the CC-PCR technique. Finished water samples were neutralized with a solution of 2%sodium thiosulfate (Sigma, St. Louis, MO) using an inline DEMA injector (DEMA, St. Louis,MO) at a flow rate of 10.0 ml/min. Cryptosporidium samples were collected according toMethod 1622 (USEPA, 1998) using the Envirochek(TM) sampling capsule (Pall Life Sciences,Ann Harbor, MI) and filtration of 100 L of finished water at a flow rate of 2.0 L/minute.Infectious Cryptosporidium oocysts were detected using the cell culture PCR (CC-PCR) assay(Di Giovanni et al. 1999). For positive controls, live Cryptosporidium parvum oocysts from theHarley-Moon strain (NADC-USDA, Ames, IA), bovine genotype; no older than four weeks werepurchased from the Sterling Parasitology Laboratory, University of Arizona, I(Tucson, AZ). Todetermine the genotype of the Cryptosporidium isolates, the hsp70 amplicon was cloned usingthe TOPO TA Cloning Kit (Invitrogen; Carlsbad, CA) in accordance with the manufacturer'sinstructions. To rule out the possibility that laboratory positive control samples (Harley-Moonstrain oocysts) could have contaminated finished drinking water samples during processing,original hsp70 PCR reactions, which had been kept frozen (at -80C or -20C) for two to twenty-fourmonths were reexamined for the gp60 marker as described by Strong et al. (2000). Includes 27 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/15/2003

Number of Pages:

15

File Size:

1 file , 390 KB