AN EVALUATION OF METHODS FOR THE SIMULTANEOUS DETECTION OF CRYPTOSPORIDIUM OOCYSTS AND GIARDIA CYSTS FROM WATER

Methods for the simultaneous detection of Cryptosporidium parvum oocys ts and Giardia cysts from water are described and their relative recov ery efficiencies are assessed for seeded samples of both tap and river water, Cartridge filtration, membrane filtration, and calcium carbona te flocculation were evaluated, and steps to optimize the concentratio n procedures were undertaken, Increasing centrifugation to 5,000 x g, coupled with staining in suspension, was found to increase the overall efficiency of recovery of both cysts and oocysts, Cartridge filtratio n for both cysts and oocysts was examined by use of 100-liter volumes of both tap and river water, Improvements in recovery were observed fo r Cryptosporidium oocysts after extra washes of the filters, Calcium c arbonate flocculation gave the maximum recovery for both Cryptosporidi um oocysts and Giardia cysts and for both water types, A variety of 14 2-mm membranes was examined by use of 10-liter seeded samples of tap a nd river water, Cellulose acetate with a 1.2-mu m pore size provided t he best results for Cryptosporidium oocysts, and cellulose nitrate wit h a 3.0-mu m pore size did so for Giardia cysts.