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

Abstract

Objective: To perform a comparative diagnosis of Cryptosporidium infection in fresh and old stool specimens. Methods: A 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. Results: Auramine 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). Conclusions: The 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.

Keywords

• Cryptosporidium
• PCR
• ELISA