Author(s): Vasylyeva, Tetyana I. ; Plessis, Louis du ; Pineda-Peña, Andrea C. ; Kühnert, Denise ; Lemey, Philippe ; Vandamme, Anne-Mieke ; Gomes, Perpétua ; Camacho, Ricardo J. ; Pybus, Oliver G. ; Abecasis, Ana B. ; Faria, Nuno R.
Date: 2019
Persistent ID: http://hdl.handle.net/10400.26/58099
Origin: Egas Moniz - Cooperativa de Ensino Superior, CRL
Subject(s): HIV; Portugal; phylodynamics; epidemiology; reproductive number; transmission groups; harm reduction
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.
