Field studies of drug-resistant cattle trypanosomes in Kénédougou Province, Burkina Faso.

Field studies were conducted to assess the occurrence of resistance to isometamidium chloride and diminazene aceturate in trypanosomes infecting cattle in Kénédougou Province of Burkina Faso. Forty-five of the 166 villages in Kénédougou were randomly sampled and visited to assess livestock numbers, trypanosomosis risk, and tsetse challenge. The proportion of cattle infections associated with drug-resistant trypanosomes was assessed in the nine villages with the highest trypanosome infection prevalence and one village with a confirmed history of drug-resistant infections. These studies showed that resistance to both isometamidium and diminazene was widespread. However, there was considerable variation between villages in drug-resistance parameters, with the proportion of treated cattle with trypanosome infections 3 months after isometamidium prophylaxis varying from 6.9 to 63.8% and the proportion of cattle having infections 2 weeks after treatment with diminazene varying from 0 to 36.8%. The demonstration of widespread resistance to both isometamidium and diminazene has important implications, as administration of trypanocides is the most commonly employed method to control trypanosomosis in this area.