The public health burden of Plasmodium falciparum malaria in Africa: deriving the numbers

In the present analysis we have modified our Pan-African malaria risk criteria and used the fuzzy membership model to delineate four areas of Africa: Class 1 (white: areas) where either there is no human settlement or zero fuzzy climate values for malaria transmission. Class 2 (yellow areas) where populations are exposed to marginal risks of malaria transmission and these risks are uncommon on an average year (fuzzy suitability greater than zero but less than 0.25). Class 3 (orange areas) where populations are exposed to a fuzzy suitability value greater than or equal to 0.25 but less than 0.75 corresponding approximately to acute seasonal transmission with a tendency toward epidemics. Finally Class 4 (brown areas) represent populations exposed to stable endemic malaria transmission which may still vary seasonaly (fuzzy suitability greater than 0.75). (excerpt)