DNA Probe Hybridization and PCR Detection of Cryptosporidium Compared to Immunofluorescence Assay

There is a need for the development of methods for the detection of Cryptosporidium in environmental samples. Two assays which detect the DNA of this parasite were developed and compared to the traditional method of detection, immunofluorescence assay (IFA). Oligonucleotide primers hybridizing to small subunit ribosomal RNA coding sequences were used in the polymerase chain reaction to develop highly specific detection of Cryptosporidium species. The PCR assay could detect about 20-100 oocyst equivalents in clean samples, but the sensitivity was reduced in some environmental samples. Detection based on direct hybridization of repetitive DNA probes from C. parvum was also accomplished, but the assay was not as sensitive as PCR or IFA and yielded false positive signals with environmental samples.