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Background: The present study was carried out to investigate the accurate status of ovine Theileria infection in sheep from Ahvaz and surrounding region, a tropical area southwest Iran., Methods: A PCR-RFLP method based on 18S ribosomal RNA gene was designed which could detect and differentiate Theileria and Babesia spp. and also differentiate main Theileria species in sheep at the same time. 119 sheep blood samples were collected from Ahvaz and surroundings., Results: Microscopic examination of blood smears revealed 69.7% (83/119) infection with Theileria spp. Of the total samples subjected to PCR, 89% (106/119) were found to be positive, all of which were identified as Theileria by RFLP analysis using enzyme Hind II. In enzymatic digestion of PCR products by Vsp I, 91.5% (97/106) of Theileria positive samples were identified as T. ovis while mixed Theileria infections were found in 9 samples. The samples with mixed infections were analyzed with an additional nested PCR-RFLP method, by HpaII enzyme digestion. 3 samples with T. lestoquardi infection, 1 sample with T. ovis and T. annulata, 1 sample with T. lestoquardi and T. annulata, and 4 samples with T. ovis, T. lestoquardi and T. annulata mixed infections were detected., Conclusion: Ovine theileriosis caused by T. ovis is highly prevalent in southwest Iran while T. lestoquardi and T. annulata infection can be detected in a lesser propor-tion of sheep in this region. The new PCR-RFLP method that was designed in this study, can serve as a beneficial diagnostic tool, especially in T. ovis prevalent re-gions.

Background: Anaplasma ovis infections can cause clinical symptoms in acute phase and lead to huge economic losses in flocks. The aim of the present study was to investigate the hematological and parasitological changes in experimental anaplasmosis in sheep with Iranian strain of A. ovis., Method: Five male sheep without any blood parasite infection were selected. One hundred ml heparinized blood was collected from splenectomised sheep that showed 6% A. ovis parasitemia. Inoculums of 20 ml blood were administered intravenously to each test animal. Hematological, parasitological and clinical changes of experimental anaplasmosis were studied in 0-38 days post infection., Result: Parasitemia was detected 3 days post infection and reached its maximum level on the day 12 of experiment in test animals. Then the parasitemia was declined, but the organism could be found persistently until the last day of study. The red cell counts, packed cell volume and hemoglobin concentration were decreased and mean corpuscular volume was increased significantly during the infection period. Reticulocytosis and basophilic stippling were also detected. No significant changes were observed in total and differential leukocyte count and animal body temperature., Conclusion: Experimental A. ovis infection in sheep resulted in marked normocytic normochromic anemia at the beginning of the infection which became macrocytic normochromic by the development of the disease. There were negative correlations between parasitemia and RBC, PCV and Hb values, therefore hematological assessment can be considered as a practical diagnostic tool in ovine anaplasmosis.