ABSTRACT
Cattle in tropical and Mediterranean regions are susceptible to theileriosis, a serious tick-borne disease that impairs animal health and productivity and causes significant financial losses. This study aimed to determine the prevalence of Theileria spp. infection among crossbred cattle in Assiut Province, Upper Egypt, using microscopic examination and molecular PCR confirmation. A total of 200 blood samples were collected from crossbred cattle, including 84 apparently healthy animals and 116 animals presenting clinical signs suggestive of theileriosis. Microscopic examination of Giemsa-stained blood smears revealed an overall prevalence of Theileria spp. infection of 38.5% (77/200). Infected animals were more frequently observed among the clinically suspected group, with a significantly higher prevalence of 54.31%, compared to the apparently healthy group. Analysis of epidemiological factors revealed that age-related analysis showed that cattle older than one year had a higher infection rate (47.5%), and females exhibited greater prevalence than males. Seasonal variation was evident; infection rates peaked during the hot season at 44.23% and declined to 32.29% in the cold season, although these factors (age, sex and season) were not statistically significant (P> 0.05). Tick infestation was significantly associated with Theileria spp. infection (P< 0.05), indicating its crucial role in disease transmission. Molecular confirmation of selected heavily infected samples was performed using PCR targeting the Tams1 gene, successfully amplifying a 721 bp fragment, confirming the presence of T. annulata. This study concludes a moderate prevalence of Theileria spp. infection in crossbred cattle in Assiut Province, highlighting the critical need for integrated tick management and diagnostic surveillance to mitigate health and economic impacts.
Key words: Cattle, Epidemiology, Molecular identification, PCR, Theileria annulata, Ticks, Assiut, Egypt.