In Africa, there are 250–450 million cases of malaria per year, and the annual economic losses associated with this are estimated to be ~ $US 2 billion. Some 10 million km2 of the malaria-affected regions of sub-Saharan Africa are also infested with tsetse flies which transmit trypanosomiasis, a complex of diseases affecting the health and productivity of humans and livestock, which has been estimated to cost Africa $US 4.5 billion a year. The use of insecticide-treated cattle to control tsetse is an increasingly important means of controlling trypanosomiasis, especially for poorer livestock owners. In the more arid, tsetse-affected regions of east and southern Africa, the main vector of malaria is Anopheles arabiensis, which obtains a significant proportion of its bloodmeals from cattle. Theoretical evidence suggests that in areas where malaria is transmitted by this vector, the insecticidal treatment of cattle could reduce malaria incidence.
