Selective detection of viable Cryptosporidium oocysts by PCR

Although the diagnosis of cryptosporidiosis in diarrheic patients is relatively simple, as large amounts of oocysts are usually shed, environmental samples can contain only few oocysts which have a comparatively high epidemiological relevance. Very sensitive detection methods are therefore requested in environmental hygiene. Additionally these methods should allow a statement about the viability of the detected organisms. The combination of a DNA-digest and a viability assay followed by a PCR might reveal a very promising method. A DNA-digest destroys free DNA in the sample. In the following excystation protocol only viable sporozoites excyst. A PCR carried out now gives definitive proof of viable oocysts. Dead sporozoites within intact oocyst-walls are not detected.