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posted 01/31/06

Climate Forecasting Systems Help Predict Malaria Risk in Africa


The Center for National Health Development in Ethiopia leads a demonstration on the proper use of a mosquito net, which can greatly reduce incidences of malaria.

A recent study published in Nature shows that climate forecasts can help predict malaria epidemics many months in advance. These predictions can alert health service managers to changes in epidemic risk five months before the peak malaria season and four months earlier than predictions based on actual rainfall.

The study appears in the February 2 issue of Nature.

Malaria is one of the world's biggest killers, taking the lives of more than one million people and infecting an estimated 500 million every year. Africa is home to 90 percent of all cases.

Climate variability has an important effect on malaria in epidemic-prone areas in Africa, where temperatures and rainfall drive both mosquito and parasite dynamics. In semi-arid Botswana, the National Malaria Control Programme has developed an early-warning system based on population vulnerability, rainfall, and health surveillance to predict and detect unusual changes in the seasonal pattern of disease. The risk of an epidemic in Botswana increases dramatically shortly after a season of good rainfall. Systems developed by the DEMETER project make forecasts of seasonal rainfall for much of southern Africa more reliable.

An important influence on rainfall in this region is the El Niño/Southern Oscillation (ENSO) which impacts the occurrence of epidemic and non-epidemic years.

By using a number of climate models the researchers were able to consider the uncertainties in the predictions which could then be expressed reliably as probabilities. Overall, the researchers' findings show that these probabilistic climate forecasts can be combined and used effectively in malaria forecasting.

According to the study, these forecasts can provide health service managers with warnings of changes in epidemic risk five months before the peak malaria season and four months earlier than predictions based on actual rainfall. Following Botswana's lead, integrated early warning systems are now being developed in conjunction with epidemic prevention and response planning activities, in a number of Southern African countries.

"What we have demonstrated in this project, which makes it unique, is the speed at which cutting-edge climate research can be translated into operational activity in Africa," said Madeleine Thomson, research scientist at the International Research Institute for Climate and Society, part of The Earth Institute at Columbia University. "This happened because research activities were linked directly to the operational needs and policy objectives of both the climate and health institutions in the region."

"In Africa malaria causes over a million deaths each year — mostly in young children," said Dr. Charles Delacollette, WHO Global Malaria Programme. "In epidemic prone regions it is a much more indiscriminate cause of death. This study demonstrates that judicious use of climate information is an important factor in reducing the impact of this devastating disease."

The study involved researchers at the International Research Institute for Climate and Society, part of The Earth Institute at Columbia University; the European Centre for Medium-Range Weather Forecasts, the National Malaria Control Programme in Botswana, and the University of Liverpool.

The International Research Institute for Climate and Society assists countries in their ability to understand, anticipate and manage climate risks, particularly in the developing world. From environmental monitoring and forecasting to climate-related risk management tools and practices in water resources, public health, agriculture, and food security, IRI and its partners focus on opportunities to build capacity for bringing climate information into regional planning and decision-making. The IRI was established and is supported under a joint cooperative agreement between U.S. NOAA Office of Global Programs (U.S. NOAA Climate Office) and Columbia University, and is part of The Earth Institute.

The Earth Institute at Columbia University is the world's leading academic center for the integrated study of Earth, its environment and society. The Earth Institute builds upon excellence in the core disciplines — earth sciences, biological sciences, engineering sciences, social sciences and health sciences — and stresses cross-disciplinary approaches to complex problems. Through research, training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world's poor. For more information, visit