Tropical Diseases Lacking Adequate Control Measures: Dengue, Leishmaniasis, and African Trypanosomiasis

Abstract

Dengue, leishmaniasis, and African trypanosomiasis (sleeping sickness) are serious diseases that the World Health Organization (WHO) characterizes as lacking effective control measures. They are transmitted by insect vectors and can result in epidemic outbreaks. Specific treatment is unavailable for dengue, although good supportive treatment can drastically reduce mortality. For the leishmaniases and for sleeping sickness, treatment relies largely on antiquated drugs based on antimony and arsenic, respectively. Sustained control of the insect vectors is difficult for dengue and leishmaniasis because their high reproductive potential allows the vector populations to recover quickly after intervention wherever adequate breeding conditions exist. By contrast, tsetse flies, the vectors for sleeping sickness, have a much lower reproductive potential and could be eliminated over large areas, given adequate organization and surveillance. Through the African Union, African nations are developing a large-scale initiative for areawide elimination of tsetse flies, partly because of sleeping sickness, but also because of their importance as vectors of animal trypanosomiasis, which poses a serious constraint to livestock development and agriculture.