Drug resistance in African animal trypanosomes: A review

Animal African trypanosmiasis (AAT) is the most important factor contributing to the sub potential performance of livestock. AAT is caused by Trypanosoma congolense, Trypanosoma vivax and Trypanosoma brucei. Chemotherapy and chemoprophylaxis are the major means of combating the disease. An estimated 17 million cattle are treated with trypanocides annually. The emergence of drug-resistant trypanosome strains is considered a serious problem in trypanosomiasis control particularly for the resource-poor, at-risk populations and farmers in Africa. Trypanocidal drug resistance is the decreased or absence of sensitivity of trypanosome strains to standard quality trypanocidal drugs at the dose recommended in a good veterinary practice. Different resistance mechanisms are acquired independently through exposure to different drugs. A good example for this is cross resistance for diminazene and isometamidium. Trypanosomiasis drug resistance has been officially reported in 21 African countries. Moreover, certain African countries reported the presence of multi drug resistance. Safeguarding the available trypanocidal drugs is mandatory to reduce the devastating impact of the disease.