Figure 1

A diagram of human infection dynamics in the Ross-Macdonald model, which was used for planning during the GMEP. Changes in the fraction of infected humans, denoted X, were described by two simple rules. The incidence rate of new infections or "force of infection", denoted h, describes the per capita rate that uninfected humans would become infected. Clearance of existing infections, the per capita rate that infected humans lose infections, was denoted r. Human infection dynamics are described by an equation: = h(1 - X) - rX, where the superdot represents the derivative with respect to time.