A cross sectional study was carried out from October, 2007 to March, 2008 to determine the prevalence of bovine trypanosomiasis and tsetse apparent density using parasitological, entomological and questionnaire survey in Birbir valley Gawo-Dalle district. The overall prevalence of bovine trypanosomosis was 13.4%. Trypanosoma congolense was identified as the dominant species (71.8%) followed by Trypanosoma brucei (14.1%), Trypanosoma vivax (10.7%) and mixed species (2.5%). Statistically significant difference was observed in the prevalence of trypanosomosis among the study sites (p < 0.001) and seasons (p < 0.05) while there was no variation between sex of animals (p > 0.05). A mean PCV of 26.26% (95% CI = 25.87 to 26.65%) was recorded in aparasitaemic cattle while in parasitaemic animals, it was 22.82% (95% CI = 22.19 to 23.44%). The anemia was seen the trypanosome infected as compared to non-infected animals (t = 6.566, p < 0.001). PCV value was found to be negatively correlated with the prevalence of trypanosomosis (r = -0.1666). In conclusion, the trypanosomosis is the major constraint to cattle production and the most widely distributed tsetse flies species are T. congolense followed by T. vivax and T. brucei. Therefore, an appropriate control measures should be employed to save the animal population under treat due to trypanosomosis and emphasis should be given to the vector control in integrated disease control strategy.

Keywords: Cattle, Ethiopia, flies, Gawo-Dalle, trypanosomosis.