Molecular prevalence and phylogenetic analysis of theileria ovis and theileria lestoquardi in small ruminants in Siirt province, Türkiye

Theileriosis is a haemoparasitic disease of domestic and wild ruminants, caused by Theileria species, transmitted by Ixodid tick species, particularly prevalent in tropical and subtropical regions. This study aimed to investigate the prevalence of Theileria ovis and Theileria lestoquardi in sheep and goats in Siirt province using molecular methods and to analyse their evolutionary relationships with published sequences. Materials and Methods: The animal material of the study consisted of 350 sheep and 350 goats in Siirt province and its districts. Blood samples were collected from the jugular veins of the animals and put into EDTA tubes. DNA extraction, PCR amplification and sequence analyses were performed on the collected samples. Results: According to the analysis results, the prevalence of T. ovis was found to be 5.43% (19/350, 95% confidence interval [CI] = 3.50%–8.32%) in sheep, 4.57% (16/350, 95% CI = 2.83%–7.30%) in goats and 5% (35/700) in total. A higher prevalence was determined in females (5.20%) and in the 2–3 age group (5.52%). Among sheep breeds, the highest prevalence was detected in Hamdani sheep (8.26%), while in goats, it was detected in Aleppo goats (7.27%). Among locations, the highest prevalence was determined in the Tillo district (10.34%). As a result of the research, Theileria lestoquardi was not found in either sheep or goats. Conclusion: This research confirmed the presence of T. ovis in sheep and goats in Siirt province, but T. lestoquardi was not detected. In future studies, a more detailed investigation of the presence of vector ticks and the development of regional control strategies is recommended.