Abstract

Study on sensitivity to diminazene aceturate 3.5 mg/kg and isometamidium chloride 0.5 mg/kg in tenzebu calves experimentally infected with two field isolates of Trypanosoma congolense (ET/07/Konso 59 and ET/07/Konso 114) was undertaken in Konso district, Southern Ethiopia. Calves were monitored for clinical and parasitological parameters during three months. At day 15 post-infection, corresponding to peak parasitaemia, they were treated with Diminasan^® 3.5 mg/kg body weight via deep intramuscular route. Out of ten calves, only two remained parasitologically negative for 12 and 15 days after treatment with Diminasan^®. Once relapse/breakthrough infection was detected in two calves, parasitemia persisted until they get second treatment with Veridium^® 0.5 mg/kg body weight. However, linear regression analysis of the effects of persistent trypanosomal infections on mean packed cell volume (PCV) and loss of body condition in relation to the initial recordings in the relapsed calves was not statistically significant. Results of the trypanocidal drug sensitivity study revealed the presence of T. congolense populations exhibiting resistance to diminazene aceturate. It is strongly recommended that legislations be devised and implemented to ensure that only quality and effective trypanocidal drugs should get access to the market.

Key words: Trypanosoma congolense, trypanocidal drugs, sensitivity test, Southern Ethiopia, calves.