DETECTION OF CRYPTOSPORIDIUM-PARVUM AND CRYPTOSPORIDIUM-MURIS OOCYSTSIN SPIKED BACKWASH WATER USING 3 PCR-BASED PROTOCOLS

Cryptosporidium parvum is an important protozoan that was shown in rec ent years to be responsible for a number of water-borne outbreaks of d iarrhoea. In this study, ways to improve the extraction of DNA from pu rified C. parvum oocysts and from backwash water (a heavily contaminat ed by-product of sand filtration), for use in the polymerase chain rea ction (PCR) were Investigated. The use of a commercial DNA purificatio n kit reduced overall assay time as dib the inclusion of an excystatio n step. In addition, a comparison was made between the detection limit s of three PCR based protocols (standard, nested and arbitrary primed (AP)-PCR) for the detection of C. parvum and C. muris, The three PCR p rotocols were assayed using serially diluted DNA extracted from purifi ed C. parvum and C. muris oocysts, and from backwash water spiked with known numbers of C. parvum oocysts. Nested PCR was the most sensitive PGR-based method tested for detecting C. parvum DNA followed by AP-PC R and standard PCR, Therefore, a system based on nested PCR for the ro utine monitoring of backwash water may act as a first-line detection t est for the presence of C. parvum oocysts in raw water treated for hum an consumption.