Malaria remains the single largest threat to child survival in sub-Snhnmn A
frica and warrants long-term investment for control. Previous malaria distr
ibution maps have been vague and arbitrary. Marlies Craig, Bob Snow and Dav
id le Sueur here describe a simple numerical approach to defining distribut
ion of malaria transmission, based upon biological constraints of climate o
n parasite and vector development. The model compared well with contemporar
y field data and historical 'expert opinion' maps, excepting small-scale ec
ological anomalies. The model provides a numerical basis for further refine
ment and prediction of the impact of climate change on transmission. Togeth
er with population, morbidity and mortality data, the model provides a fund
amental tool for strategic control of malaria.