Detection of tropical bovine theileriosis by polymerase chain reaction in cattle

Abstract

Tropical bovine theileriosis, a tick borne disease, caused by, Theileria annulata with marked clinical signs of pyrexia (102-105°F), enlargement of lymphnodes etc., causes heavy economic losses in terms of high mortality and morbidity rates. Diagnosis of theileriosis is mainly based on clinical symptoms and microscopic examination of stained blood smears and lymph node biopsy smears but limitations of these methods against Theileria sp. limits the specificity. Hence, to overcome the limitations, the present study reports the detection of T. annulata in blood samples of cattle by polymerase chain reaction. The study was conducted on 155 cattle having typical clinical symptoms and blood smear after staining with Giemsa stain was examined for the presence of T. annulata in RBC. The Primer sequences were used as per d'Oliveira et al. The assay employs primers specific for the gene encoding the 30-kDa major merozoite surface antigen of T. annulata and the amplification of 721bp was done. Out of the total 155 animals, 34 were positive for T. annulata by blood smear method whereas 134 samples were positive by PCR. So diagnosis of blood samples by PCR is found to be the most sensitive and specific methodology as compared to cytological blood smear examination. The sensitivity was 23.88% and specificity was 90.47% of blood smear method considering PCR as gold standard and it was found that PCR is more sensitive than the conventional method of examination.