Background: Tick-borne diseases caused by Anaplasma, Babesia, and Theileria species cause significant economic losses and are common in tropical and subtropical regions of the world. The aim of this study was to investigate the presence and genetic diversity of Anaplasma ovis, Babesia ovis, and Theileria spp. in blood sheep with clinical signs in Ilam province. Methods: A total of 73 blood samples were collected from early June to late September 2023 and 2024 from sheep in different areas of Ilam province. After using the method of Giemsa-stained smears of peripheral blood and identified by a compound microscope, 1 ml blood samples were collected from the jugular vein of each sheep in EDTA tubes for polymerase chain reaction (PCR). The genomic DNA of blood was extracted 549-bp and 778-bp fragment of 18S-rRNA gene and 347-bp fragment of MSP4 was amplified by PCR. Results: Piroplasm infections were microscopically observed in the blood smears. PCR amplification of whole-blood DNA detected Theileria spp. 61/73 (56.83%), and A. ovis 20/73 (39.27%). No Babesia ovis was detected in whole-blood samples. Theileria ovis was the only Theileria species identified following the sequencing of all PCR-positive Theileria spp. and A.ovis Conclusion: Our results showed that Anaplasma ovis is present in sheep in Ilam province. Although it was not properly detected and recognized in microscopic observations, it is recommended to use molecular tests to detect parasitic infections due to their high sensitivity and accuracy.l
