Malaria forecast

Meteorology can predict incidence five months in advance

By Kirtiman Awasthi
Published: Wednesday 15 March 2006

climate forecasting systems can help predict malarial outbreaks, particularly in Africa where the disease is acute, five months in advance, says a recent study. Conducted by researchers at Botswana's National Malaria Control Programme (nmcp), Columbia University, usa, University of Liverpool and the European Centre for Medium-Range Weather Forecasts (ecmwf) in the uk, the study was published in Nature (Vol. 439, No 7076, February 2, 2006).

The early warning system (ews) for malaria is based on a climate forecast model called demeter. ews takes into account the changes in rainfall patterns and temperature. Although extreme temperatures kill mosquitoes, temperatures between 15 c and 30 c increase the rate of development, the researchers say. Increased rainfall provides mosquitoes more breeding sites . Besides, an earlier research (published in American Journal of Tropical Medicine and Hygiene; Vol 73, No 1, July 2005) had reported how climate variables (rainfall and sea surface temperature) influence the incidence of malaria in Botswana.

The research focused on variation in temperature and rainfall during the months when malaria transmission occurred. Using data on confirmed malaria incidence in Botswana from 1982-2002, the study revealed that variability in rainfall (in December-February) was directly related to variability in malaria incidence (in January-May). The relationships of variability in rainfall and sea surface temperatures to malaria incidence are assessed after removing the impact of non-climatic trends," says T N Palmer of ecmwf .

The ensemble of climate models used give probabilistic predictions of high rainfall for Botswana ahead of the rainy season and using the malaria-rainfall relationship, risk assessment of malaria incidence can be made," claimed the study. Though the current predictions (based on a different climate model) are slightly more accurate, they can be made only a month in advance.

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