Prevalence of Babesia bigemina and Theileria orientalis in Domestic Cattle (Bos taurus) Across the Three Geo-Climatic Zones of Sri Lanka

Abstract

Theileria orientalis and Babesia bigemina are hemoprotozoan parasites that adversely affect domestic cattle (Bos taurus) productivity and health worldwide. Rapid climatic changes in different geo-climatic zones observed over the past few years may have altered the distribution and transmission of tick-borne pathogens and vectors. Though these parasites are reported in Sri Lanka in surveillance records, there is a limited understanding of their current distribution pattern. The present study aimed to determine the prevalence and genetic characterization of B. bigemina and T. orientalis in cattle from three geo-climatic zones of Sri Lanka during the period from January 2025 to March 2026. Out of 384 samples collected from animals (wet, n = 124; dry, n = 208; and intermediate, n = 52 zones) in Sri Lanka, the overall prevalence of 60.2% for T. orientalis and 7.6% for B. bigemina was revealed using PCR-based detection methods. The highest prevalence of T. orientalis was observed in the wet zone (86.3%), while the highest prevalence of B. bigemina was 17.3% in the intermediate zone. Co-infections were detected in 5.7% of cattle across all three zones. These results indicate the dominance of T. orientalis compared with B. bigemina in cattle in Sri Lanka. The observation of co-infections highlights the importance of vector control against vector-borne diseases in Sri Lanka.