Determine the Prevalence of Theileria spp. Infection and Associated Biochemical Changes in Naturally Infected Sheep in Al-Kharj City, Saudi Arabia

Theileriosis is a tick-borne hemoparasitic disease affecting both domestic and wild small ruminants and is widely distributed in tropical and subtropical regions. It is primarily transmitted by ticks of the genera Hyalomma and Haemaphysalis, leading to considerable economic burdens due to reduced productivity, increased treatment costs and mortality.

This study aimed to determine the prevalence of Theileria spp. infection and its associated biochemical alterations in sheep in Al-Kharj, Saudi Arabia. The study was conducted from July to October 2025 and included 280 sheep (92 males and 188 females) from 26 randomly selected herds. Blood samples were aseptically collected via jugular venipuncture for serum separation and biochemical analysis. Detection of Theileria infection was performed microscopically using Giemsa-stained blood smears.

The overall prevalence of Theileria spp. infection was 13.9%. Infected sheep showed clinical signs such as pale mucous membranes, anorexia and tick infestation, with slightly higher infection rates observed in younger sheep (≤2 years) and females. Biochemical findings revealed significantly elevated liver enzymes (ALT, AST and ALP) (independent samples t-test, p<0.001) and decreased total protein levels, indicating hepatic dysfunction and impaired protein metabolism. Additionally, significant mineral imbalances were observed, including reduced calcium and increased phosphorus levels (p<0.001), while significantly elevated creatinine and urea concentrations (p<0.001) suggested renal involvement. These results demonstrate the systemic effects of Theileria infection on sheep health in the study area.