Assessment of the Resistance of Cattle Trypanosomes to Diminazene Aceturate and Isometamidium Chloride on the Adamawa Plateau in Cameroon Using a Field Test and a Test in Mice

Abstract

Based on a survey in a few villages of the department of Faro et Deo, the village of Kontcha, where the highest trypanosomosis prevalence (32.5%) was observed, was selected to evaluate the resistance of trypanosomes to diminazene and isometamidium. Two groups of 40 head of cattle each were treated on day 0 either with diminazene or with isometamidium. The animals were monitored every other week for a period of two months using the buffy coat technique to assess the level of parasitemia. The percentages of trypanosome infected animals in the groups treated with diminazene and isometamidium were 32.5 and 27.5%, respectively. The survival analysis and mean hazard ratio (1.38) suggested resistance to isometamidium and a reduced protective activity of this drug. Several animals treated with diminazene at 7 mg/kg tested positive two weeks after treatment, indicating a strong suspicion of resistance to this trypanocidal compound. These field results were corroborated by the standard mouse test using six Trypanosoma congolense isolates. Sensitivity tests using 1 mg/kg isometamidium chloride and 20 mg/kg diminazene aceturate showed that all isolates were resistant at least to one of the drugs, whereas four isolates were resistant to both drugs. This study shows for the first time the presence in Cameroon of drug-resistant trypanosome strains.

Keywords

• Bovin
• Trypanosoma
• Antiprotozoaire
• Résistance aux produits chimiques
• Cameroun