Development of a nested-PCR assay for the detection of Cryptosporidium parvum in finished water

A nested-PCR assay, incorporating an internal positive control, was develop ed for Cryptosporidium monitoring in finished water. This assay was capable of reproducibly detecting 8 oocysts in spiked-filtered water samples colle cted from 5 South Australian water treatment plants. The RT-PCR assay of Ka ucner and Stinear (Appl. Environ. Microbiol. 64(5) (1998) 1743) was also ev aluated for the detection of Cryptosporidium parvum. initially, under our e xperimental conditions, a detection level of 27 oocysts was achieved for sp iked reagent water samples. This level was improved to 5 oocysts by modific ation of the method. Untreated South Australian source waters concentrated by calcium carbonate flocculation were found to be highly inhibitory to the RT-PCR assay. Concentration of similar samples using Envirochek filters ap peared to eliminate PCR inhibition. While both methods possessed similar se nsitivities the nested-PCR assay was more reproducible, more cost effective , simpler to perform and could detect both viable and non-viable intact Cry ptosporidium parvum oocysts, which is an important consideration for plant operators. These factors make the nested-PCR assay the method of choice for screening large numbers of potable water samples, where a reliable low lev el of detection is essential. (C) 2001 Elsevier Science Ltd. All rights res erved.