Tracing the Impact of Public Health Interventions on HIV-1 Transmission in Portugal Using Molecular Epidemiology

Tetyana I. Vasylyeva, Louis Du Plessis, AC Pineda-Peña, Denise Kühnert, Philippe Lemey, AM Vandamme, Perpétua Gomes, Ricardo Jorge Camacho, Oliver George Pybus, AB Abecasis, Nuno Rodrigues Faria

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13 Citations (Scopus)


BACKGROUND:Estimation of temporal changes in human immunodeficiency virus (HIV) transmission patterns can help to elucidate the impact of preventive strategies and public health policies.METHODS:Portuguese HIV-1 subtype B and G pol genetic sequences were appended to global reference data sets to identify country-specific transmission clades. Bayesian birth-death models were used to estimate subtype-specific effective reproductive numbers (Re). Discrete trait analysis (DTA) was used to quantify mixing among transmission groups.RESULTS:We identified 5 subtype B Portuguese clades (26-79 sequences) and a large monophyletic subtype G Portuguese clade (236 sequences). We estimated that major shifts in HIV-1 transmission occurred around 1999 (95% Bayesian credible interval [BCI], 1998-2000) and 2000 (95% BCI, 1998-2001) for subtypes B and G, respectively. For subtype B, Re dropped from 1.91 (95% BCI, 1.73-2.09) to 0.62 (95% BCI,.52-.72). For subtype G, Re decreased from 1.49 (95% BCI, 1.39-1.59) to 0.72 (95% BCI, .63-.8). The DTA suggests that people who inject drugs (PWID) and heterosexuals were the source of most (>80%) virus lineage transitions for subtypes G and B, respectively.CONCLUSIONS:The estimated declines in Re coincide with the introduction of highly active antiretroviral therapy and the scale-up of harm reduction for PWID. Inferred transmission events across transmission groups emphasize the importance of prevention efforts for bridging populations.
Original languageEnglish
Article numberjiz085
Pages (from-to)233-243
Number of pages10
JournalJournal of Infectious Diseases
Issue number2
Publication statusPublished - 19 Jun 2019


  • HIV
  • Phylodynamics
  • Epidemiology
  • Reproductive number
  • Transmission groups
  • Harm reduction
  • Portugal


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