Drug Resistant Trypanosomes: a Threat to Cattle Production in the Southwest of Ethiopia

Abstract

Trypanosomosis is an important disease of cattle in the southwest of Ethiopia. At present chemotherapy and chemoprophylaxis are the only practical methods available for the control of animal trypanosomosis, but their effectiveness is being eroded by the emergence of drug resistant trypanosomes. Of the drugs available for the treatment of animal trypanosomosis, Berenil^® (diminazene aceturate) and Trypamidium^® (isometamidium chloride) have been used the most because of their availability and relatively low toxicity to cattle. In this study, four stocks of Trypanosoma congolense, originally isolated from cattle in the southwest of Ethiopia (Ghibe, Bedelle, Sodo and Arbaminch), were tested for their Berenil and Trypamidium sensitivity using Swiss white mice and indigenous zebu cattle. The results on the limited number of stocks indicated the existence of drug resistant strains of T. congolense. Isolates from Ghibe, Bedelle and Sodo were resistant to a therapeutic dose of diminazene aceturate (3.5 mg/kg) and to standard therapeutic and prophylactic doses of isometamidium chloride (0.5 and 1 mg/kg). However, all three stocks were found to be sensitive to 7 mg/kg diminazene aceturate. The fourth, the Arbaminch stock, was found to be resistant to the manufacturers’ recommended doses of diminazene aceturate and isometamidium chloride.