HIV SeropositivityHIV SeroprevalenceHIV InfectionsDisease ProgressionAcquired Immunodeficiency SyndromeSubstance Abuse, IntravenousSexual BehaviorHIV-1Risk FactorsSeroepidemiologic StudiesViral LoadSimian Acquired Immunodeficiency SyndromeSimian immunodeficiency virusnef Gene Products, Human Immunodeficiency VirusMacaca mulattaCohort StudiesCD4-Positive T-LymphocytesAntibodies, ViralAntibodies, BacterialChlamydophila pneumoniaeImmunoglobulin GChlamydophila InfectionsEnzyme-Linked Immunosorbent AssaySerologic TestsHIV SeronegativityPrevalenceHelicobacter pyloriHelicobacter InfectionsToxocariasisCytomegalovirus InfectionsAntibodies, ProtozoanAIDS SerodiagnosisCross-Sectional StudiesCase-Control StudiesToxoplasmosisHepatitis CHerpesvirus 2, HumanToxocaraCD4 Lymphocyte CountBlood DonorsProspective StudiesPapillomavirus InfectionsHomosexualityTime FactorsAge FactorsRural PopulationNeosporaAIDS-Related Opportunistic InfectionsCytomegalovirusBrazilAnti-HIV AgentsSyphilisHerpes GenitalisImmunoglobulin AToxoplasmaHuman papillomavirus 16Cell CycleOdds RatioFollow-Up StudiesImmunoglobulin MRisk-TakingHIV AntigensSexual PartnersHomosexuality, Male