Drug resistance in recent isolates of Trypanosoma brucei and Trypanosoma congolense

Abstract

Studies were carried out in mice to assess the drug sensitivity of recent isolates of Trypanosoma brucei and Trypanosoma congolense. Each of eleven stocks of T. congolense and five stocks of T. brucei all isolated from cattle was tested for sensitivity to normal therapeutic dose of isometamidium chloride, diminazene aceturate and homidium chloride. Contemporaneous control tests were carried out on authenticated laboratory stocks of T. brucei and T. congolense. Six stocks of T. congolense were resistant to diminazene aceturate at 3.5 mg/kg but only one stock was found resistant to 7 mg/kg. Ten isolates of the T. congolense group were resistant to homidium chloride at 1 mg/kg. All the T. congolense isolates were susceptible to isometamidium chloride at 0.5 mg/kg. Two of the T. brucei were resistant to diminazene aceturate at 7 mg/kg while all were resistant to homidium chloride at even 3 mg/kg. All T. brucei isolates were sensitive to isometamidium chloride at 0.5 mg/kg. The control trypanosomes were readily sensitive to the three drugs at normal therapeutic doses.