Comparison of molecular and microscopic technique for detection of Theileria spp. in carrier cattle.

In Iran, theileriosis is normally diagnosed with traditional Giemsa staining method. This is not applicable for identification of the carrier animals. The aim of this study was to compare conventional Giemsa staining method with the PCR technique in the detection of Theileria organisms. In this study, examinations were performed on 150 blood samples from cattle without clinical signs. Sensitivity and specificity of 50 microscopic fields were compared with Theileria specific PCR. The degree of agreement between PCR and microscopic test was determined by Kappa (κ) values with 95 % confidence intervals. PCR showed that 42 samples were Theileria spp. positive, while routine microscopy showed erythrocytes harboring Theileria like structures in 11 blood samples. Examination of 50 microscopic fields showed 57 % sensitivity and 99 % specificity compared to 100 % sensitivity and specificity for PCR. The κ coefficient between PCR and Microscopy (50 fields) techniques indicated no level of agreement. Our results showed that the microscopic examination remains the convenient technique for day-to-day diagnosis of clinical cases in the laboratory but for the detection of carrier animal containing low parasitemia. Therefore, molecular methods such as PCR can be used as a safe method for identifying cattle persistently infected with Theileria spp.