At the beginning of the twenty-first century, Brazil ranked second only to the United States in the number of reported cases of AIDS. Because Brazil's extensive poverty and inequality, its fragile economic situation, and its limited network of health services, the scarce prevention/intervention resources targeted only the most visible at risk populations -- gay men, sailors, prostitutes, and street children. Virtually forgotten were Brazil's hidden drug users, as well as the tens of millions of individuals living in the country's thousands of favelas, or shantytowns, which are a...