Phylogenetic analysis of the Belgian HIV-1 epidemic reveals that local transmission is almost exclusively driven by men having sex with men despite presence of large African migrant communities

Chris Verhofstede, Kenny Dauwe, Katrien Fransen, Kristel Van Laethem, Sigi Van den Wijngaert, Jean Ruelle, Marie-Luce Delforge, Ellen Vancutsem, Dolores Vaira, Karolien Stoffels, Sergio Garcia Ribas, Geraldine Dessilly, Laurent Debaisieux, Denis Pierard, Marc Van Ranst, Marie-Pierre Hayette, Jessica Deblonde, Andre Sasse, Dominique Van Beckhoven, Virginie Mortier

    Research output: Contribution to journalA1: Web of Science-articlepeer-review


    To improve insight in the drivers of local HIV-1 transmission in Belgium, phylogenetic, demographic, epidemiological and laboratory data from patients newly diagnosed between 2013 and 2015 were combined and analyzed. Characteristics of clustered patients, paired patients and patients on isolated branches in the phylogenetic tree were compared. The results revealed an overall high level of clustering despite the short time frame of sampling, with 47.6% of all patients having at least one close genetic counterpart and 36.6% belonging to a cluster of 3 or more individuals. Compared to patients on isolated branches, patients in clusters more frequently reported being infected in Belgium (95.1% vs. 47.6%; p <0.001), were more frequently men having sex with men (MSM) (77.9% vs. 42.8%; p <0.001), of Belgian origin (68.2% vs. 32.9%; p <0.001), male gender (92.6% vs. 65.8%; p <0.001), infected with subtype B or F (87.8% vs. 43.4%; p <0.001) and diagnosed early after infection (55.4% vs. 29.0%; p <0.001). Strikingly, Sub-Saharan Africans (SSA), overall representing 27.1% of the population were significantly less frequently found in clusters than on individual branches (6.0% vs. 41.8%; p <0.001). Of the SSA that participated in clustered transmission, 66.7% were MSM and this contrasts sharply with the overall 12.0% of SSA reporting MSM. Transmission clusters with SSA were more frequently non-B clusters than transmission clusters without SSA (44.4% versus 18.2%). MSM-driven clusters with patients of mixed origin may account, at least in part, for the increasing spread of non-B subtypes to the native MSM population, a cross-over that has been particularly successful for subtype F and CRF02-AG.

    The main conclusions from this study are that clustered transmission in Belgium remains almost exclusively MSM-driven with very limited contribution of SSA. There were no indications for local ongoing clustered transmission of HIV-1 among SSA.

    Original languageEnglish
    JournalInfection, Genetics and Evolution
    Pages (from-to)36-44
    Number of pages9
    Publication statusPublished - 2018


    • HIV-1 transmission
    • HIV-1 in Belgium
    • Men who have sex with men
    • Phylogenetic clustering
    • HIV-1 in Sub-Saharan African migrants
    • TYPE-1

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