With disease mapping there is a tendency to focus on high risk areas and to ignore a more detailed study of low risk areas. Plotted data in the next slide shows the low annual case incidence of 0.2% or less along the coast during the period 1980 - 1991. This is a marked change from 1938 when this same coastal area between lake St. Lucia and Kosi Bay was the high risk area. The efforts of the malaria control programme appear to have eradicated one of the two main vectors, Anopheles funestus during that time. The breeding sites in this area are those favoured by A. funestus (which was recorded as malaria vector in 1931). The remaining vector A. arabiensis does not favour these sites and is largely absent from the area.
Average Annual Malaria Incidence per Control Sector in Ingwavuma and Ubombo, 1980-1991