Review on Diagnostic Techniques of Bovine Theileriosis

Bovine Theileriosis is one of the neglected tick-borne hemoprotozoan diseases of cattle, with significant economic impacts, particularly in East African countries. The disease caused by several Theileria species.  Among them, T. parva and T. annulata cause East Coast fever and tropical theileriosis, respectively. The geographical distribution of tropical theileriosis is mainly determined by the location and biology of its vector, with T. parva occurring in east African countries like Kenya and Somalia and T. annulata occurring from southern Europe to Asia. The former causes East Cost Fever (ECF) and is one of the economical important vector borne diseases in east Africa. The two major tick species discriminated to serve as vectors of the pathogen are Rhipicephalus appendiculatus and Hyalomma anatolicum which transmit T. parva and T. annulata, respectively. Despite its importance, the development of new diagnostic tools has been stagnant, and existing ones are poorly documented and fragmented. Therefore, this paper aims to review the overall diagnostic techniques of bovine theileriosis, with specific objectives of reviewing existing diagnostic techniques and assessing their advantages and disadvantages. The review highlights the complexity of Theileria life cycles, involving both vertebrate and invertebrate hosts, making diagnosis possible in both hosts and vectors. Diagnosis of theileriosis is performed using both clinical and laboratory techniques. Generally, diagnostic approaches in the host include microscopic examination of Giemsa-stained thin/thick blood films for detection of piroplasms and lymph node biopsy smears for detection of schizonts. Serological tests (Immunofluorescent Antibody Test, Enzyme-linked Immunosorbent Assay, and Indirect Hemagglutination Assay) and molecular techniques like Polymerase Chain Reaction. While xenodiagnosis is used to diagnose parasite stages in vector ticks. The review concludes that PCR is currently the most accepted diagnostic tool due to its high sensitivity (100%) and specificity (100%). However, its use is limited to large laboratories and research institutions. Overall, this review emphasizes the need for improved diagnostic tools and increased access to existing ones to effectively manage bovine theileriosis, a neglected disease with significant economic impacts in East Africa.