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The Effect of Climate Change on Malaria in Western Africa
Reference
Jackson, M.C., Johansen, L., Furlong, C., Colson, A. and Sellers, K.F. 2010. Modelling the effect of climate change on prevalence of malaria in western Africa. Statistica Neerlandica 64: 388-400.

Background
The authors write that "malaria is one of the most devastating vector-borne parasitic diseases in the tropical and subtropical regions of the world," where they say it affects over 100 countries. Thus, it should come as no surprise that according to the World Health Organization, Africa carries the highest infection burden of any continent, with nearly 200 million cases reported in 2006; and the Centers for Disease Control and Prevention estimate that between 700,000 and 2.7 million people die annually from the dreaded disease (Suh et al., 2004). In addition, Jackson et al. report that "the African region bears 90% of these estimated worldwide deaths," and that "three-quarters of all malaria related deaths are among African children," citing Breman (2001) in this regard. As a result, they -- as well as many others -- opine that "malaria could be greatly affected by the influence of climate change," such as that associated with global warming. But is this really the case?

What was done
In an effort designed to shed some light on this important question, the five U.S. researchers linked reported malaria cases and deaths from the years 1996 to 2006 that they obtained from the World Malaria Report (2008) for ten countries in western Africa (Benin, Burkina Faso, Cote d'Ivoire, Gambia, Ghana, Liberia, Mali, Senegal, Sierra Leone and Togo) with corresponding climate data they obtained from the U.S. National Oceanic and Atmospheric Administration's National Climatic Data Center, after which they searched for transitive relationships between the weather variables and malaria rates via spatial regression analysis and tests for correlation.

What was learned
Jackson et al. report that their analyses showed that "very little correlation exists between rates of malaria prevalence and climate indicators in western Africa."

What it means
This result, as they describe it, "contradicts the prevailing theory that climate and malaria prevalence are closely linked and also negates the idea that climate change will increase malaria transmission in the region."

References
Breman, J.G. 2001. The ears of the hippopotamus: manifestations, determinants, and estimates of the malaria burden. American Journal of Tropical Medicine and Hygiene 64: 1-11.

Sun, K.N., Kain, K.C. and Keystone, J.S. 2004. Malaria. Canadian Medical Association Journal 170: 1693-1702.

Reviewed 26 January 2011