HIV SeropositivityHIV SeroprevalenceHIV InfectionsSubstance Abuse, IntravenousSexual BehaviorRisk FactorsDisease ProgressionSeroepidemiologic StudiesAntibodies, ViralAntibodies, BacterialChlamydophila pneumoniaeImmunoglobulin GChlamydophila InfectionsEnzyme-Linked Immunosorbent AssaySerologic TestsHIV SeronegativityPrevalenceHematologic NeoplasmsHelicobacter pyloriHelicobacter InfectionsAcquired Immunodeficiency SyndromeNeoplasmsToxocariasisCase-Control StudiesHIV-1Cytomegalovirus InfectionsAntibodies, ProtozoanCohort StudiesCross-Sectional StudiesProspective StudiesRetrospective StudiesTime FactorsToxoplasmosisCell Line, TumorHepatitis CFollow-Up StudiesHerpesvirus 2, HumanToxocaraPapillomavirus InfectionsBlood DonorsAge FactorsAIDS SerodiagnosisTreatment OutcomeIncidencePrognosisCell CycleCD4 Lymphocyte CountNeosporaCytomegalovirusRural PopulationHuman papillomavirus 16Odds RatioImmunoglobulin AGene Expression Regulation, NeoplasticHerpes GenitalisBrazilSyphilisToxoplasmaHomosexualityImmunoglobulin MMultivariate AnalysisSensitivity and SpecificityHomosexuality, Male