Determinants of human immunodeficiency virus (HIV) prevalence in homosexual and bisexual men screened for admission to a cohort study of HIV negatives in Belo Horizonte, Brazil: Project Horizonte.

Project Horizonte, an open cohort of homosexual and bisexual human immunodeficiency virus (HIV-1) negative men, is a component of the AIDS Vaccine Program, in Belo Horizonte, Minas Gerais, Brazil. The objective of this study was to compare volunteers testing HIV positive at cohort entry with a sample of those who tested HIV negative in order to identify risk factors for prevalent HIV infection, in a population being screened for enrollment at Project Horizonte. A nested case-control study was conducted.