IMMUNOMAGNETIC SEPARATION OF CRYPTOSPORIDIUM-PARVUM FROM SOURCE WATERSAMPLES OF VARIOUS TURBIDITIES

Immunomagnetic separation (IMS) procedures which specifically capture Cryptosporidium oocysts and have the potential to isolate oocysts from debris have become commercially available. We compared two IMS kits ( kit DB [Dynabeads anti-Cryptosporidium; product no. 730.01; Dynal A.S. , Oslo, Norway] and kit IC1 [Crypto Scan IMS; product no. R10; Clearwa ter Diagnostics Company, LLC, Portland, Maine]) and a modification of kit IC1 (kit IC2 [Crypto Scan IMS; product no. R10; Clearwater Diagnos tics Company, LLC]) at three turbidity levels (50, 500, and 5,000 neph elometric turbidity units [ntu]) by using water matrices obtained from different geographical locations. In deionized water, kit DB yielded recoveries between 68 and 83%, whereas the recoveries obtained with ki ts IC1 and IC2 were more variable and ranged from 0.2 to 74.5%. In wat er matrices with turbidity levels up to 500 ntu, the oocyst recoveries were more variable with kit DB; however, the recoveries were similar to those obtained in deionized water. In contrast, there were notable reductions in oocyst recoveries in the turbid matrices with kits IC1 a nd IC2, and the highest recovery (8.3%) was obtained with a 50-ntu sam ple. An examination of the effects of age on oocyst recovery with kit DB revealed that oocysts up to 16 weeks old yielded recoveries similar to the recoveries observed,vith fresh oocysts, These data indicate th at all IMS kits do not perform equally well, and it is important to co nduct in-house quality assurance work before a commercially available IMS kit is selected to replace flotation procedures for recovery of Cr yptosporidium oocysts.