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Malaria Rates Defy Global Warming Fears

By Stephen Luntz

Malaria rates are falling even though warming trends are more extending the range of mosquitoes.

Malaria rates in East Africa are dropping even though climate change is making conditions more suitable for mosquitoes, according to a study published in PLoS One.

Prof David Stern of the Australian National University’s Crawford School of Economics and Government says that malaria rates rose in the area during the 1990s but have fallen since. “In research we published in 2002 in Nature we could not find a statistically significant trend in temperatures in the region, sparking heated debate about what caused the increase in malaria in the area at the time,” Stern says.

“This new research applies recently developed statistical tests to a quality controlled temperature series from Kericho in East Africa, and when the last 15 years of data are included we can see a statistically significant trend.” While the warming trend is now clear, malaria rates are falling.

Stern is a statistician but he says that his co-authors who conducted the research in Kenya attribute the previous rise in frequency to the development of parasitic resistance to the drugs used to treat infection. In recent years a range of new anti-malarial drugs have become available. Besides saving lives, these drugs reduce parasite load, making it less likely that a mosquito will pick up the disease when biting someone who has been infected.

“This research suggests that, while climate change is expected to have many serious impacts, other factors including medical interventions appear to be more important in determining the incidence of malaria,” Stern says.