Climate change is one reason malaria is on the rise in some parts of the world, new research finds, but other factors such as migration and land-use changes are likely also at play. The research, published in The Quarterly Review of Biology, aims to sort out contradictions that have emerged as scientists try to understand why malaria has been spreading into highland areas of East Africa, Indonesia, Afghanistan and elsewhere.
"We assessed conclusions from both sides and found that evidence for a role of climate in the dynamics is robust," write study authors Luis Fernando Chaves from Emory University and Constantianus Koenraadt of Wageningen University in the Netherlands. "However, we also argue that over-emphasizing a role for climate is misleading for setting a research agenda, even one which attempts to understand climate change impacts on emerging malaria patterns."
Malaria, a parasitic disease spread to humans by mosquitoes, is common in warm climates of Africa, South America and South Asia. The development and survival, both of the mosquito and the malaria parasite are highly sensitive to daily and seasonal temperature patterns and the disease has traditionally been rare in the cooler highland areas. Over the last 40 years, however, the disease has been spreading to the highlands, and many studies link the spread to global warming. But that conclusion is far from unanimous. Other studies have found no evidence of warming in highland regions, thus ruling out climate change as a driver for highland malaria.
Chaves and Koenraadt re-examined more than 70 of these studies. They found that the studies ruling out a role for climate change in highland malaria often use inappropriate statistical tools, casting doubt on their conclusions.
For example, an oft-cited 2002 study of the Kericho highlands of western Kenya found no warming trend in the area. But when Chaves and Koenraadt ran the same temperature data from that st
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