Through the alteration of temperatures and rainfall patterns, climate change is expected to affect the distribution of environmental suitability for malaria transmission. However, local and global impacts are very much uncertain. In order to contribute to a better understanding of these issues, this study, conducted by the Massachusetts Institute of Technology, assesses the effect of climate change on malaria transmission in a West African context.
The methodology consisted of the coupling of a detailed mechanistic hydrology and entomology model with climate projections from general circulation models (GCMs). This was then used to predict changes in vectorial capacity resulting from changes in the availability of mosquito breeding sites and temperature-dependent development rates. To mitigate the fact that different GCMs disagree on climate projection figures, the best- and worst-case scenarios for malaria transmissions were selected for each zone of the study area.
Results of the analysis concluded that: Under a worst-case scenario, vectorial capacity would increase along the edge of the Sahara, but not sufficient to sustain transmission.
A decrease is predicted in vectorial capacity in the transitional zone of the Sahel
In the wetter, southern regions, all scenarios point toward an increase in vectorial capacity. Despite this, increased rates of malarial infection are likely to be small in the southern regions, given the already highly endemic situation among human populations.
The study concludes that rainfall is an important factor shaping the impact of climate change on malaria transmission in the future. Yet even in the GCM scenarios most conducive to malaria transmission, the authors do not expect to see a significant increase in malaria prevalence in the region.