Malaria and other vector borne diseases will increase in frequency with higher (nocturnal) temperatures. Malaria climbs up high altitude areas where it has not previously been a serious threat. In recent years it has become clear that climate change will have direct and indirect impacts on diseases that are endemic in Africa. Following the 1997-1998 El Niño event, malaria, Rift Valley fever, and choler a outbreaks were recorded in many countries in East Africa.
The meningitis belt in the drier parts of West and Central Africa is expanding to the eastern region of the continent. These factors are superimposed upon existing weak infrastructure, land-use change, and drug resistance by pathogens such as Plasmodium falciparum and Vibrio cholerae. Although the principal causes of malaria epidemics in the African highlands still are a subject of debate in the literature (Mouchet et al., 1998), there is increasing evidence that climate change has a significant role (WHO, 1998). In a highland area of Rwanda, for example, malaria incidence increased by 337% in 1987, and 80% of this variation could be explained by rainfall and temperature (Loevinsohn, 1994). A similar association has been reported in Zimbabwe (Freeman and Bradley, 1996). Other epidemics in East Africa have been associated largely with El Niño.
It can be expected that small changes in temperature and precipitation will support malaria epidemics at current altitudinal and latitudinal limits of transmission (Lindsay and Martens, 1998). Furthermore, flooding could facilitate breeding of malaria vectors and consequently malaria transmission in arid areas (Warsame et al., 1995). The Sahel region, which has suffered from drought in the past 30 years, has experienced a reduction in malaria transmission following the disappearance of suitable breeding habitats. Yet, there are risks of epidemics if flooding occurs (Faye et al., 1995 ) .