The spatial limit of Plasmodium falciparum malaria risk defined by P. falciparum annual parasite incidence ( Pf API) with temperature and aridity masks. Areas were defined as stable (dark grey areas, where PfAPI ≥ 0.1‰ pa), unstable (middle grey areas, where PfAPI < 0.1‰ pa) or no risk (light grey) [17–19]. The borders of the 87 countries defined as P. falciparum endemic are shown. The community surveys of P. falciparum prevalence conducted between 1985 and 01 March 2008 are plotted. Of the 4,887 surveys that could be geo-positioned, 4,077 fell within the predicted limits of P. falciparum malaria risk. The data shown are age-standardized (Pf PR2–10) and shown as a continuum from 0–100%. The dashed lines indicate the separation between the area defined as 'Africa+' (Africa, Yemen and Saudi Arabia) and the rest of the world used in the analyses.