Suspected resistance of Trypanosoma species to diminazene aceturate on a cattle farm in Nigeria

African animal trypanosomiasis is a major cause of mortality and economic losses for the livestock industry in Nigeria. Chemotherapy has been the most reliable option for cattle herders, and the most commonly found drug on the market is diminazene aceturate. To ascertain the long-term efficacy of this compound, we sampled a cattle herd in Ogun State, Nigeria, 2 months after they were treated with diminazene aceturate. The ITS-PCR results revealed 19 positives for trypanosome DNA out of the 79 samples tested (24.1%, 95% CI 16.0-34.5). Seventeen out of the total 19 positives were Trypanosoma congolense (21.5%, 95% CI 13.9-31.8). Mixed infections were also observed. Therefore, the persistence of bovine trypanosomiasis at this Nigerian cattle farm despite treatment could be due to diminazene aceturate resistant trypanosomes being present in the herd.