Detection of Native Carrier Cattle Infected with Theileria annulata by Semi-Nested PCR and Smear Method in Golestan Province of Iran

Theileria annulata, as a pathogenic agent of tropical theileriosis, gives rise annually to serious economic losses in cattle industry of Iran. The carrier cattle, harbouring the latent forms of Theileria annulata, play a major role in infecting tick vectors and in disseminating the infection. The aim of this study was determining the carrier cattle, infected with Theileria annulata in Golestan province of Iran by semi-nested PCR method in comparison with Smear method. In this study 160 blood samples, collected from apparently healthy native cattle, were examined. The Tbs-S/Tbs-A primer set was used for PCR amplification of Theileria sp. and the Ta-S/Tbs-A specific primer set was used in semi-nested PCR technique for detection of Theileria annulata. Blood smears of each case were examined by Giemsa staining method, too. The semi-nested PCR accurately revealed 12 (7.5%) positive samples; whereas Giemsa staining method could detect 6 (3.75%) out of 160 blood samples. The results indicated that Giemsa staining method, having 50% sensitivity, is not suitable for determination of Theileria annulata carrier cattle, while semi-nested PCR technique can be used as a Gold standard method for the mentioned aim and also can be used for screening of Theileria annulata carrier cattle in all regions.