Abstract / Summary
Cattle in Ethiopia face a significant threat from trypanosomosis, a parasitic disease caused by Trypanosoma protozoa and transmitted through the bite of tsetse flies. However, control efforts face challenges due to misuse of trypanocidal drugs, which contribute to treatment failures and economic losses. A two-phase study was conducted from March 2023 to March 2024 in selected hotspot villages of the Bench-Sheko and Sheka zones, Southwest Ethiopia. The first phase involved a cross-sectional survey to determine the prevalence and distribution of bovine trypanosomosis, while the second phase consisted of a longitudinal field drug-efficacy trial to evaluate the efficacy of diminazene aceturate (DA) and isometamidium chloride (ISM) against bovine trypanosomosis.Villages with the highest trypanosome infection prevalence, ranging from 21.05% to 32.00%, were identified based on the findings of the cross-sectional study. Subsequently, a 28-day field protocol study was employed to estimate treatment failure to 1 mg/kg body weight ISM and 7.0 mg/kg body weight DA. In this study, 100 trypanosome-positive cattle were purposively selected, ear-tagged, and randomly allocated to two treatment groups. Group I was treated with a 2% solution of ISM, while Group II received a 7% solution of DA. The treatment day was designated as day 0. The treated cattle were monitored for trypanosomes and packed cell volume (PCV) levels on days 14 (for both DA and ISM) and 28 (for ISM) post-treatment. A treatment failure rate of ≥ 25% among cattle in the ISM-treated group on days 14 and 28 was considered indicative of treatment failure. In the DA-treated group, the response was assessed only on day 14 post-treatment. High rates of DA treatment failure were observed, with 66.67% in Koyi and 60.00% in Selam Bari, while ISM treatment failures reached 75.00% in Charbay and 66.67% in Koyi at 14- and 28-days post-treatment, respectively. T. congolense was the most prevalent species among treatment failures, accounting for 52.24% in DA-treated cattle and 50.00% in ISM-treated cattle at 14 days post-treatment. Overall, among the 50 cattle that tested positive for trypanosomes and were treated with ISM, 30% remained infected on day 28 post-treatment. However, among the 50 cattle treated with DA, 42% of the positive cattle had detectable trypanosomes on day 14 post-treatment. Trypanocidal drug failure is severe in study areas, and its impact on livestock health is significant. These results underscore the need for further study to explore more deeply the causes of treatment failure and to safeguard livestock health and production in endemic areas.