Highways and outposts: economic development and health threats in the central Brazilian Amazon region

BACKGROUND Economic development is often evoked as a driving force that has the capacity to improve the social and health conditions of remote areas. However, development projects produce uneven impacts on local communities, according to their different positions within society. This study examines the spatial distribution of three major health threats in the Brazilian Amazon region that may undergo changes through highway construction. Homicide mortality, AIDS incidence and malaria prevalence rates were calculated for 70 municipalities located within the areas of influence of the Cuiabá-Santarém highway (BR-163), i.e. in the western part of the state of Pará state and the northern part of Mato Grosso. RESULTS The municipalities were characterized using social and economic indicators such as gross domestic product (GDP), urban and indigenous populations, and recent migration. The municipalities' connections to the region's main transportation routes (BR-163 and Trans-Amazonian highways, along with the Amazon and Tapajós rivers) were identified by tagging the municipalities that have boundaries crossing these routes, using GIS overlay operations. Multiple regression was used to identify the major driving forces and constraints relating to the distribution of health threats. The main explanatory variables for higher malaria prevalence were: proximity to the Trans-Amazonian highway, high proportion of indigenous population and low proportion of migrants. High homicide rates were associated with high proportions of migrants, while connection to the Amazon River played a protective role. AIDS incidence was higher in municipalities with recent increases in GDP and high proportions of urban population. CONCLUSIONS Highways induce social and environmental changes and play different roles in spreading and maintaining diseases and health threats. The most remote areas are still protected against violence but are vulnerable to malaria. Rapid economic and demographic growth increases the risk of AIDS transmission and violence. Highways connect secluded localities and may threaten local populations. This region has been undergoing rapid localized development booms, thus creating outposts of rapid and temporary migration, which may introduce health risks to remote areas.