The appearance of isometamidium resistant Trypanosoma congolense in West Africa

The frequent reappearance of patent parasitemia, mainly Trypanosoma congolense, in cattle maintained under isometamidium prophylaxis in the Upper Volta indicated that drug-resistant forms might be appearing. To investigate this possibility, trypanosome stocks were isolated in mice, their isometamidium sensitivity estimated and compared to that of stocks isolated before drug use was widespread. Most T. congolense stocks isolated in 1982-1983 were 4-8 times less sensitive to isometamidium than those isolated in 1979-1980.