Detection of carrier cattle infected to Theileria annulata by molecular assay in northwest of Iran

Bovine theileriosis, caused by Theileria annulata, is one of the most important livestock diseases in the world. The disease is transmitted by Ixodidae ticks and characterized by fever, enlargement of lymphatic glands, cachexia, and death. theileriosis can be detected by staining the blood smear Giemsa dye. The technique is suited the detection of acute infection but not in carrier animals, where infection rate may be little. The aim of present study was to detect T. annulata carrier cattle by polymerase chain reaction (PCR) and to compare the results with staining method in the northwest of Iran. Materials and Methods: In this study, peripheral blood samples were obtained from 281 apparent healthy cattle (no clinical signs of disease) of different ages (1 to 8 years old). Samples were tested by two techniques of (1) Giemsa staining and microscopy and (2) PCR based on applying the specific primers from the major merozoite-piroplasm surface antigen sequence of T. annulata (Tams-1) gene. A chi-square test was performed to compare the prevalence related to breed and age categories. Results: In this study, 25 T. annulata positive samples (8.89%) were detected by microscopic method while PCR was able to detect 108 samples (38.43%) for. In positive samples of cattle, the highest prevalence was recorded for 2-5 years old cattle (22.4%). These differences in age results were significant (P 0.05). Out of 108 positive PCR samples, 45 (41.66%) were native and, 63 (58.33%) were crossbreed cattle, yet the difference was statistically insignificant. Conclusion: Our results showed that there is a high percentage of carrier cows in northwest of Iran and indicate a high potential risk for the infestation of healthy animals and vectors of the disease.