HIV SeropositivityHIV SeroprevalenceHIV InfectionsSubstance Abuse, IntravenousSexual BehaviorRisk FactorsSeroepidemiologic StudiesChronic DiseaseChlamydophila pneumoniaeAntibodies, ViralChlamydophila InfectionsAntibodies, BacterialImmunoglobulin GSerologic TestsEnzyme-Linked Immunosorbent AssayToxoplasmosisHelicobacter pyloriHelicobacter InfectionsToxoplasmaPrevalenceHIV SeronegativityHepatitis CAntibodies, ProtozoanHIV-1Cytomegalovirus InfectionsHepatitis BToxocariasisViral LoadAcquired Immunodeficiency SyndromePseudomonas InfectionsCase-Control StudiesHepacivirusCross-Sectional StudiesCytomegalovirusCD8-Positive T-LymphocytesPseudomonas aeruginosaImmunoglobulin AToxoplasmosis, AnimalToxocaraHerpesvirus 2, HumanAntibodies, HelminthAIDS SerodiagnosisImmunoglobulin MBlood DonorsChlamydia InfectionsCystic FibrosisHerpesviridae InfectionsAntigens, BacterialHepatitis C AntibodiesNeosporaHepatitis C, ChronicCD4 Lymphocyte CountPapillomavirus InfectionsCohort StudiesHIV AntigensAcute DiseaseRural PopulationQ FeverSyphilisHerpes GenitalisOdds RatioCD4-Positive T-LymphocytesHepatitis B Surface AntigensLymphocytic choriomeningitis virusTrichuriasisAge FactorsBrazilAnti-HIV AgentsHepatitis B virusLymphocytic ChoriomeningitisCoxiella burnetiiHomosexualityBacterial ProteinsChagas Disease