AWWA WQTC69504

This study focuses on recovery efficiencies of whole Cryptosporidium parvum oocysts using "off-the-slide" extraction techniques. The extraction approach was evaluated in two phases: removal of the coverslip and mounting media; and, transfer of the oocysts from the slide to the genotyping tube. C. parvum oocysts were counted by flow cytometry to contain 200, 20 or 0 oocysts per well. The coverslip was then removed and retained, and the well was washed. The coverslip and washed well were recounted. Results show that the number of oocysts remaining on the well was variable after removal of the coverslip and mounting media, ranging from nearly 50% to 95%. Less than 2% of the oocysts on average were attached to the coverslip, with the remaining oocysts removed with the mounting media. These results suggest that removal of the coverslip accounts for little oocyst loss; however, the mounting media retained on the slide must be transferred to the genotyping tube to accurately reflect the oocysts on the slide. Includes 8 references, abstract only.