Recognition of Cryptosporidium oocysts in fresh and old stool samples: comparison of four techniques

ABSTRACTObjectiveTo perform a comparative diagnosis of Cryptosporidium infection in fresh and old stool specimens.MethodsA total of 518 stool samples including 464 diarrheic human samples, 53 samples from calves with or without diarrhea and one sample from a sheep were screened. Initially, the auramine phenol, modified Ziehl-Neelsen and ELISA techniques, were preformed. Subsequently, PCR of the 18S rRNA gene of Cryptosporidium was carried out on all positive samples obtained by microscopy and ELISA.ResultsAuramine phenol and Ziehl-Neelsen identified Cryptosporidium oocysts in 49 (9.5%) and 56 (10.8%) out of 518 samples, respectively. Cryptosporidium specific antigen was found in 97/518 (18.7%) of the samples by the ELISA test. The 18S rRNA gene of the parasite was amplified in 79 out of 119 (66.4%) samples by PCR. Comparison of the detection rates between the diagnostic methods, i.e. PCR and ELISA, showed that there was a moderate level of agreement between these tests (Kappa=0.55).ConclusionsThe current study suggested that PCR or ELISA methods with one of microscopy technique should be used for screening of Cryptosporidium infection in a stool sample collection.