"Conventional wisdom" in the scientific community has it that global warming of the last century raised temperatures in high-altitude African mountain villages sufficiently to extend the range of malaria-carrying mosquitoes and therefore be the cause of malaria increases being observed in these regions. The numbers of severe cases and deaths related to malaria have risen by 30 to 800 % over the last 15-25 years in portions of Uganda, Kenya, and nearby regions. However, Hay et al (2002) examine climate changes during this period and find no evidence that climatic factors favoring the spread of mosquitoes (increases in temperature and humidity) have changed in these regions.
Reference
Hay, S. I., J. Cox, D. J. Rogers, S. E. Randolph, D. I. Stern, G. D. Shanks, M. F. Meyer, and R. W. Snow, 2002: Climate change and the resurgence of malaria in East African highlands. Nature, 415, 905-909.