The map on the left shows the geographic variation in prevalence of malaria. Areas in red have widespread malaria, while green shading illustrates areas in which malaria does not occur. Yellow shading indicates malaria in some locations.

Several factors contribute to high prevalence in Africa. These include an efficient vector, i.e., the Anopheles mosquito, the high prevalence of Plasmodium falciparum (the parasite that causes the most severe cases of malaria), weather conditions that encourage year-round transmission, and inadequate malarial control and prevention measures due to inadequate resources and socio-economic structures in many African nations. Malaria is also a significant problem in Southeast Asia and parts of Central and South America.

[Map source: CDC]

The female anopheles mosquito is the sole transmitter of the plasmodium parasite, since they require blood meals for egg development, and males do not. Transmission of plasmodium depends on the anopheles mosquito's ability to bite, and therefore inject the plasmodium parasite into a human, as well as its lifespan. The longer a mosquito can live, the more developed the parasite can become before it is transmitted. In many parts of Africa, anopheles mosquitos live longer than elsewhere, due in large part to inadequate mosquito control mechanisms in rural areas, making them more deadly and more likely to pass on a mature parasite in the late stages of development (as a sporozoite).   Complete maturity of the parasite at transmission requires an adult mosquito lifespan of at least 10-18 days.  

Anopheles mosquitoes are active at night, and tend to bite most between dusk and dawn.

 Click here for more information on the Anopheles mosquito.