Molecular Characterization of Tropical Theileriosis among Local and Imported Dairy Cattle in Duhok Governorate–Kurdistan Region/Iraq

Bovine tropical theileriosis, caused by Theileria annulata, was surveyed in dairy cattle herds of Duhok Governorate, Kurdistan Region, Iraq. In a cross-sectional study of 212 cattle, Giemsa-stained microscopy was compared to nested PCR (n-PCR), and the determinant risk factors and phylogenetic relationships were investigated. The microscopic and PCR prevalence of infection was 12.7 and 21.7, respectively (P≤0.0001). Age increased prevalence by a significant margin (P≤0.032): cattle 5 years old were almost four times more likely to be infected as compared to calves. Poor body condition was a significant determinant as opposed to sex and breed effects, which were not significant (P≤0.0001). Risk was also predisposed by management variables, outdoor grazing, and infrequent use of acaricides (P≤0.0001). The phylogenetic analysis was done using 10 local 18S rRNA sequences (GenBank accessions OP435250-OP435259), and all Duhok isolates appeared in one clade, but some of them were extremely close to a strain present in the neighboring countries (99-100% identity). These results suggest regional genetic continuity and most likely cross-border spread. To sum up, T. annualata causes a significant epidemiological impact in dairy cattle in Duhok. The superior sensitivity of PCR, the strong influence of age, body condition, and management practice, and the evidence of regional strain circulation underscore the need for enhanced molecular surveillance, regimented acaricide programs, and targeted, risk-based control strategies to safeguard herd health and productivity.