African animal trypanosomosis is among the most serious livestock diseases constraining food sufficiency in Sub-Saharan Africa. This study aimed to generate base line data for implementing the trypanosomosis and tsetse fly control operations. The study was conducted from November 2014 to March 2015 in Asosa and Bambasi districts of Asosa Zone, Northwestern Ethiopia. Glossina morsitans submorsitans was the only tsetse fly species caught. The apparent density of tsetse fly was 5.77fly/trap/day (FTD). Among forty two flies dissected, five (11.90%) were found to harbor trypanosomes of T. congolense (9.52%) and T. vivax (2.38%) species. The prevalence of trypanosomosis was significantly higher in cattle (8.55%) than in donkeys (2.35%), goats (1.68%) and sheep (0.00%). In all infected study animals, T. congolense was the dominant trypanosome species (97.32%); while T. vivax accounts only 2.68% of the total infections. The mean PCV in trypanosome-infected animals was lower than in uninfected ones. African animal trypanosomosis is an important threat to animal health in the studied area and is not only a disease of concern in cattle but also in goats and donkeys. To this end, sustained interventions of trypanosomosis and its vectors, considering the epidemiological importance of cattle, small ruminants and donkeys is a prerequisite for the enhancement of livestock production in the areas where tsetse fly and trypanosomosis is prevalent.

Keywords: Asosa, Bambasi, domestic ruminants, donkeys, trypanosomosis, vectors