Preventive interventions at each visit include free condom distribution, HIV/Aids information, and participation in discussion fora addressing questions such as sexuality, HIV vaccine trials, and safe sexual practices.Results: From 1994 to 2010, 1187 volunteers were screened: 102 (8.6%) were ineligible (positive for HIV); 1085 were enrolled; 565 were lost of follow-up with 72% of the losses occurr