Climate change and future populations at risk of malaria

Global estimates of the potential impact of climate change on malaria trans mission were calculated based on future climate scenarios produced by the H adCM2 and the more recent HadCM3 global climate models developed by the UK Hadley Centre. This assessment uses an improved version of the MIASMA malar ia model, which incorporates knowledge about the current distributions and characteristics of the main mosquito species of malaria. The greatest proportional changes in potential transmission are forecast to occur in temperate zones, in areas where vectors are present but it is cur rently too cold for transmission. Within the current vector distribution li mits, only a limited expansion of areas suitable for malaria transmission i s forecast, such areas include: central Asia, North America and northern Eu rope. On a global level, the numbers of additional people at risk of malari a in 2080 due to climate change is estimated to be 300 and 150 million for P. falciparum and P. vivax types of malaria, respectively, under the HadCM3 climate change scenario. Under the HadCM2 ensemble projections, estimates of additional people at risk in 2080 range from 260 to 320 million for P. f alciparum and from 100 to 200 million for P. vivax. Climate change will hav e an important impact on the length of the transmission season in many area s, and this has implications for the burden of disease. Possible decreases in rainfall indicate some areas that currently experience year-round transm ission may experience only seasonal transmission in the future. Estimates o f future populations at risk of malaria differ significantly between region s and between climate scenarios. (C) 1999 Elsevier Science Ltd. All rights reserved.