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 proximi ty of homestead to roads. METHODS HIV prevalence measured through anonymous surveillance among pregna nt women and stratified by local village clinic. Polygons were created arou nd each clinic, assuming women attend the clinic nearest their home. A geog raphical information system (GIS) calculated the mean distance from homeste ads in each clinic catchment to nearest primary (1 degrees) and to nearest primary or secondary (2 degrees) road. RESULTS We found marked HIV heterogeneity by clinic catchment (range 19-31% (P < 0.001). A polygon plot demonstrated lower HIV prevalence in catchment s remote from 1 degrees roads. Mean distance from homesteads to nearest 1 d egrees or 2 degrees road varied by clinic catchment from 1623 to 7569 m. Th e mean distance from homesteads to a 1 degrees or 2 degrees road for each c linic catchment was strongly correlated with HIV prevalence (r = 0.66; P = 0.002). CONCLUSIONS The substantial HIV heterogeneity in this district is closely c orrelated with proximity to a 1 degrees or 2 degrees road. GIS is a powerfu l tool to demonstrate and to start to analyse this observation. Further res earch is needed to better understand this relationship both at ecological a nd individual levels, and to develop interventions to reduce the spread of HIV infection.