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Malaria areas are shifting more rapidly than expected
A Cologne study projects the future spread of malaria in Africa
The emergence and spread of malaria in Africa will have shifted drastically by the year 2050. Especially the more densely populated areas of West Africa, such as the south of Niger and the East African highlands of over 2000 meters in altitude (approx. 6500 ft.) will become increasingly more affected. It is especially there that the risk to die from malaria will increase, according to simulations by Dr. Volker Ermert and Professor Dr. Andreas H. Fink from the Institute for Geophysics and Meteorology who are working with an integrated weather-disease model. The study “The Impact of Regional Climate Change on Malaria Risk due to Greenhouse Forcing and Land-Use Changes in Tropical Africa" was published in the journal “Environmental Health Perspectives”.
The study was the first to use a regional climate model with a high spatial resolution, which factored in the impact of man-made changes on the earth's surface on the climate. Especially clearing forests in order to gain arable land drastically changes the water cycle of evaporation and precipitation, and results in less rain. The changes in environmental conditions actually slow the spread of malaria in part of West Africa. There is less stagnant water, the breeding grounds for the mosquitoes that transmit the malaria parasites to humans, and consequently, their reproduction goes down.
“Our model predicts that by 2050, there will be considerably less precipitation in most of tropical Africa. In East Africa, however, precipitation rates as well as temperatures will rise,” Dr. Volker Ermert explains. The spread of malaria will thus decrease in the Sahel region. This will cause large parts of the population to lose their immunity against malaria and make them vulnerable against emerging epidemics. This danger zone will move southwards and approach the more densely populated regions of the continent such as the south of Niger. In East Africa, Malaria will spread in the highlands and the danger of epidemics upwards of 2000 m (approx. 6500 ft.) in altitude will rise. Below this altitude, malaria will occur more stable and so be less dangerous.
The Cologne scientists based their model on the so-called Liverpool Malaria Model, developed among others by Andrew Morse. The climate data was supplied by Heiko Paeth of the University of Würzburg. Emert had to readjust the parameters for the model and in order to do so, he collected all available observational data for malaria in West Africa, such as the bite rate of infected mosquitos. The meteorologist used these measurements to calibrate the malaria model so that it would simulate realistic results.
So far, human land use was not integrated into pertinent models. Wrongly so, as Volker Ermert believes: “The effect on the precipitation is very strong. Compared to current precipitation rates, we are expecting a decrease of up to 20% for large parts of Africa. Without this effect, you cannot show a clear trend in precipitation.” This also means that the shifts in the spread of malaria will occur sooner than expected. Due to the shorter time-frame, these malaria projections will be relevant to policy makers in Africa.
Contact:
Dr. Volker Ermert,
Tel.: 0221/470-6490
email: vermert(at)meteo.uni-koeln.de
