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In tropical Africa, livestock plays a critical role in the ‘development triangle’ of food security, poverty alleviation and environmental protection (Vosti, 1995; Kitalyi et al., 2006). In traditional livestock systems, cattle provide meat, milk, draught power and manure for crop production and hence contribute to a nutritious and diverse diet. Moreover, the value of cattle includes benefits in finance, through ‘cashing’ part of the herd at a desired point in time, and the ability to cope with shock situations. On the other hand, animal diseases impair cattle productivity. To minimize disease losses, to ensure efficacy of disease management and to avoid negative externalities, adequate supply of veterinary inputs and appropriate advice on their use are required (Steinfeld, 1988). Hence,

sustainable resource management in grazing and feeding, in breeding, as well as in animal health care, reduces the risk of food insecurity and poverty and, at the same time, contributes to the preservation of natural resources also for future generations. African animal trypanosomosis (AAT) is one of the

most severe cattle health problems in sub-Saharan Africa and imposes a serious constraint on the fragile triangle described above. Costs of AAT are estimated at 4.5 billion US$ annually, considering direct and indirect losses (Budd, 1999). Strategies to control trypanosomosis comprise the following:

† keeping trypanotolerant breeds such as N’Dama or Baoule´ that are indigenous to Africa and able to limit the multiplication of trypanosomes (pathogen) and hence can ward off the infection;

† control of the tsetse fly by insecticides in the form of ground and aerial spraying, or pour-ons, or by screens and fly traps that are more environmentally friendly;

† control of pathogens (trypanosomes) by treatment with prophylactic or curative drugs.