HIV SeropositivityHIV SeroprevalenceHIV InfectionsSubstance Abuse, IntravenousSexual BehaviorRisk FactorsSeroepidemiologic StudiesAntibodies, ViralAcute DiseaseChlamydophila pneumoniaeImmunoglobulin GAntibodies, BacterialSerologic TestsToxoplasmosisChlamydophila InfectionsEnzyme-Linked Immunosorbent AssayToxoplasmaHIV-1Antibodies, ProtozoanPrevalenceHIV SeronegativityCytomegalovirus InfectionsHepatitis CImmunoglobulin MHerpesviridae InfectionsHelicobacter pyloriHelicobacter InfectionsChagas DiseaseViral LoadToxocariasisAcquired Immunodeficiency SyndromeTrypanosoma cruziCross-Sectional StudiesCytomegalovirusToxoplasmosis, AnimalCD8-Positive T-LymphocytesCase-Control StudiesToxocaraInfectionImmunoglobulin AHerpesvirus 2, HumanAIDS SerodiagnosisVirus LatencyChronic DiseaseBlood DonorsViremiaVirus ActivationCD4 Lymphocyte CountBrazilVirus ReplicationRNA, ViralCD4-Positive T-LymphocytesNeosporaQ FeverHepatitis BPapillomavirus InfectionsChlamydia InfectionsSimian Acquired Immunodeficiency SyndromeRural PopulationAnti-HIV AgentsAge FactorsSyphilisHerpes GenitalisLymphocytic choriomeningitis virusHepatitis C AntibodiesAntigens, BacterialDNA, ViralCohort StudiesSimian immunodeficiency virusParvoviridae InfectionsTime FactorsHomosexualityCoxiella burnetiiHerpes SimplexProspective StudiesParvovirus B19, HumanLymphocytic Choriomeningitis