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Malaria is a very temperature- and rainfall-sensitive disease. This means itâs one whose distribution and severity could change a lot in a warming climate. This is particularly worrying because the global burden of malaria is so high: it kills more than 600,000 people a year. Almost half a million of those are children. What effect has climate change already had on malaria, and what impact could it have in the future? In this article, we draw on a recent paper by Colin Carlson and colleagues, published in Nature, which attempts to answer this question. They find that, over the last century, climate change has likely increased the prevalence of malaria in children across Africa by a rate of 1 case per 1,000 children. To put this into context, there were around 240 cases in every 1,000 children in this region at the time. So, the impact has been relatively small and is uncertain. The bigger impact has been the change in distribution. Malaria rates have likely decreased in West Africa due to climate change. This is because warming has pushed temperatures in this subregion beyond malariaâs optimum temperature of around 25°C. In other parts of Africa, higher temperatures have pushed it towards the optimum, increasing the prevalence. Overall, the impacts of interventions to reduce malaria â bed nets, antimalarials, and improved healthcare â have far outweighed the impacts of climate change. These dynamics are expected to stay the same in the future. With more warming, the prevalence in West Africa will decrease. In other subregions, whether it increases or decreases will depend on the extent of warming. But overall, the authors expect a decline in malaria prevalence in Africa due to climate change, with an increase in certain areas that have not experienced the disease for a long time. Whatâs most uncertain about these projections is the impact of extreme weather events. When these are modeled, some project an increase in malaria cases and deaths, due to the shocks on healthcare and malaria control systems.
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