[Social networks and diffusion of AIDS in Brazil].

The HIV/AIDS epidemic has been simplistically interpreted as a phenomenon restricted to risk groups that are socially and spatially circumscribed. However, epidemic trends in recent years have demonstrated the need to employ open diffusion models that emphasize social interaction as a means of spread of HIV. This study is a spatial analysis of the AIDS epidemic in Brazil, which sought to incorporate variables reflecting economic and demographic events into a system for processing geographically referenced health information. Findings indicate that metropolises and regional urban centers, mainly those in the Southeast, play an important role in the spread of the epidemic, not only because of their population density but also because they are centers of trade and social interaction. In smaller cities located in the state of São Paulo, a large number of AIDS cases among injecting drug users are concentrated, revealing the routes and centers of cocaine use.