Abstract
Theileria annulata, a protozoan parasite of cattle is causes tropical theileriosis. Polymerase chain reaction (PCR) was used to assess the presence and the frequency of T. annulata infection in blood samples obtained from carrier cattle in Kerman, Southeast of Iran. Blood samples were collected in citrate solution from 150 native cattle with mean age of 1 year which selected randomly. Primarily, a thin layer smear was prepared from their ear sublime vein blood and was fixed with methanol and stained with Giemsa dye. Blood smears were examined for the presence of parasites, and blood samples were analyzed by PCR. Piroplasmic forms of T. annulata were seen in 16 of 150 (10.66 %) by examination the blood smears with light microscope, whereas 68 of 150 (45.33 %) cattle were positive by PCR method. All animals that were positive by blood smears were also positive by PCR. Difference between these methods was significant (P < 0.05). Our results demonstrate that this PCR assay in diagnosing T. annulata parasites in carrier cattle is more sensitive than method of smear preparation and can be used in epidemiological studies.