Molecular study and DNA sequence analysis of Theileria annulata in cattle in Al-Hilla, Iraq

The current work was conducted to unveil the current situation for the infection by Theileria annulata in cattle in Al-Hilla City, Iraq. A total of 225 blood samples (200 from suspected infected animals and 25 from clinically healthy animals as a control group) were collected. These samples were subjected to a direct slide-smearing for detection using a microscope and DNA sequencing, targeting the cytochrome b (Cyt b) gene of 10 polymerase chain reaction (PCR) products. The thin smear findings of the 200 suspected cases revealed that 63 (31.5%) were infected with Theileria spp., while 115 (57.5%) cases had no Theileria but other blood parasites; however, only 22 (11%) suspected cases showed no presence of any parasites. Unsurprisingly, the 25 blood samples from the control group demonstrated no presence of any blood parasite. Moreover, the DNA sequencing demonstrated that the Theileria spp. belonged to T. annulata species, and these sequences were nucleotide-based similar to Gene-Bank isolates from Tunisia (ON035604, ON035605, ON035606, ON035607, ON035608, ON035609, ON035610, ON035611, ON035612, and ON035613). The present study outcomes indicate that theileriosis is the dominant parasitic infection in cattle in Al-Hilla City and is highly caused by Theileria annulata.