title: Improved strategies for HIV diagnosis among men who have sex with men (MSM) in Buenos Aires, Argentina, a population with a high prevalence and incidence of HIV infection.
abstract: BACKGROUND
  In Argentina, HIV diagnosis in adults is made using one or two enzyme immunoassay tests and a confirmatory test. These strategies may fail to identify infected individuals during early primary infection, which represents an important public health problem among groups with a high HIV incidence, such as men who have sex with men (MSM) (6.3% persons/year). The general objective of this study was to contribute to reducing HIV transmission among MSM through the identification of antibody-negative, nucleic acid-positive individuals.
  
  
  RESULTS
  A total of 1549 MSM were recruited for an HIV seroprevalence study. A total of 161 (10.4%) MSM were HIV-positive and 14 (0.9%) were indeterminate. Among the 1374 negative individuals, 16 (1.2%) exhibited reactive results in the screening assay. Indeterminate Western blot (WB) samples and negative WB samples (with discordant results in the screening) were analysed to detect HIV nucleic acid by viral load testing. Up to 23.1% of HIV-indeterminate WB samples and 7.1% of HIV-negative WB samples with discordant results in the screening assays had detectable nucleic acid. Overall, 14.8% of the samples with discordant or indeterminate results were identified as HIV-positive using direct diagnosis. With the identification of four new cases using the nucleic acid detection test, the HIV prevalence in MSM increased by 0.3% (from 10.4 to 10.7%).
  
  
  CONCLUSIONS
  The results of this study suggest the importance of including nucleic acid detection in the HIV algorithm for MSM with HIV-indeterminate WB results and those with HIV-negative WB results and discordant results in screening assays, in order to decrease HIV transmission among this population with a high HIV prevalence and incidence.
authors.affiliation: Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina. mpando@fmed.uba.ar
authors.forename: M A
authors.initials: MA
authors.lastname: Pando
authors.forename: R S
authors.initials: RS
authors.lastname: Coloccini
authors.forename: N
authors.initials: N
authors.lastname: Schvachsa
authors.forename: M
authors.initials: M
authors.lastname: Pippo
authors.forename: L G
authors.initials: LG
authors.lastname: Alfie
authors.forename: R
authors.initials: R
authors.lastname: Marone
authors.forename: M
authors.initials: M
authors.lastname: Gomez-Carrillo
authors.forename: M M
authors.initials: MM
authors.lastname: Avila
authors.forename: H
authors.initials: H
authors.lastname: Salomón
mesh_terms: D000328:Adult; D000465:Algorithms; D001118:Argentina / Q000453:epidemiology; D003362:Cost-Benefit Analysis; D004279:DNA, Viral / Q000097:blood* / Q000235:genetics; D042241:Early Diagnosis; D015483:HIV Antibodies / Q000097:blood*; D006679:HIV Seropositivity / Q000175:diagnosis* / Q000453:epidemiology; D015497:HIV-1 / Q000235:genetics; D018451:Homosexuality, Male / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening; D021141:Nucleic Acid Amplification Techniques; D015995:Prevalence; D012367:RNA, Viral / Q000097:blood* / Q000235:genetics; D019562:Viral Load
chemical_list: D004279:DNA, Viral; D015483:HIV Antibodies; D012367:RNA, Viral