HIV heterogeneity and proximity of homestead to roads in rural South Africa: an exploration using a geographical information system

OBJECTIVE To describe heterogeneity of HIV prevalence among pregnant women in Hlabisa health district, South Africa and to correlate this with proximity of homestead to roads. METHODS: HIV prevalence measured through anonymous surveillance among pregnant women find stratified by local village clinic. Polygons were created around each clinic, assuming women attend the clinic nearest their home. A geographical information system (GIS) calculated the mean distance from homesteads in each clinic catchment to nearest primary (1°) and to nearest primary or secondary (2°) road. RESULTS: We found marked HIV heterogeneity by clinic catchment (range 19-31% (P < 0.001). A polygon plot demonstrated lower HIV prevalence in catchments remote from 1°roads. Mean distance from homesteads to nearest 1°or 2°road varied by clinic catchment from 1623 to 7569 m. The mean distance from homesteads to a 1°or 2°road for each clinic catchment was strongly correlated with HIV prevalence (r = 0.66; P = 0.002). CONCLUSIONS: The substantial HIV heterogeneity in this district is closely correlated with proximity to a 1°or 2°road. GIS is a powerful tool to demonstrate and to start to analyse this observation. Further research is needed to better understand this relationship both at ecological and individual levels, and to develop interventions to reduce the spread of HIV infection.