Malaria early-warning system shows promise in tackling epidemics

Climate forecasting systems help predict malaria risk in Africa

The Earth Institute at Columbia University—Malaria is one of the world’s biggest killers, taking the lives of more than 1 million people every year, as well as infecting a staggering 500 million worldwide. Although endemic in several regions of the world, malaria is most acute in Africa, home to an estimated 90 percent of all cases. Early warning systems can assist health programs and services in preventing and controlling the disease in epidemic-prone areas. A recent study shows that climate predictions can help provide health professionals and program managers with warnings of epidemics many months in advance. The study appears in the February 2 issue of Nature.

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 (http://www.ecmwf.int/research/demeter/) 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. In epidemic prone regions it is a much more indiscriminate cause of death,” said Dr Charles Delacollette, WHO Global Malaria Programme. “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. For a copy of the paper or for further information, please contact Ruth Francis, Senior Press Officer at Nature, at +44-20-7843-4562 or r.francis@nature.com.