Scientist say climate change is the root of the problem (of increased numbers at risk of Malaria in Africa), because without higher temperatures, mosquitoes could not thrive. Mosquitoes are driven by temperature.
Anopheles mosquitoes live an average of only 21 days, and at a temperature of 65 degrees or lower it takes the malaria parasite 56 days to mature. In short, the bug dies before they can become contagious. But at 72 degrees or higher, the parasite's cycle is reduced to less than three weeks, increasing chances of transmission.
Los Angeles Times