Theileria lestoquardi and Theileria ovis are the main causes of ovine theileriosis in Iran. The epidemiological aspects of ovine theileriosis in Iran are poorly understood. In our new study we used a sensitive and specific PCR-RFLP method for identification of theileria spp. In sheep.to determine the prevalence of different theileria spp. 10 different regions of Iran were selected: zabol, lar, ferdows, semnan, gorgan, sari, rasht, urmia, ilam and ahwaz. AROUND 40-50 SHEEP BLOOD SAMPLES WERE taken randomly from each area. blood samples were collected in EDTA from apparently healthy sheep. from a total 470 blood samples, 45.5 % were positive for theileria spp. by nested-pcr compared with 15.3% by microscopic examination.using RFLP of PCR products, out of 214 positive blood samples, 55.1% were positive for theileria lestoquardi and 42.9 % were positive for theileria ovis. the prevalence of these two theileria spp was compared in 10 different areas. the results showed the prevalence of T.ovis ranged from 100% in north and north west to 0 in south and south west in iran and vice versa for theileria lestoquardi. these findings helps us to understand why the endemic areas for ovine theileriosis are restricted to some local foci in Iran. this question was raised by authors for many years.

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