Article Text

Download PDFPDF
Original research
Contribution of transgender sex workers to the complexity of the HIV-1 epidemic in the metropolitan area of Milan
  1. Alessia Lai1,
  2. Annalisa Bergna1,
  3. Francesco Roberto Simonetti2,
  4. Marco Franzetti3,
  5. Giorgio Bozzi4,
  6. Valeria Micheli5,
  7. Chiara Atzori6,
  8. Annalisa Ridolfo7,
  9. Gianguglielmo Zehender1,
  10. Massimo Ciccozzi8,
  11. Massimo Galli1,
  12. Claudia Balotta1
  1. 1 Department of Biomedical and Clinical Sciences ‘L. Sacco’, University of Milan, Milano, Lombardia, Italy
  2. 2 Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
  3. 3 Infectious Diseases Unit, Alessandro Manzoni Hospital, Lecco, Lombardia, Italy
  4. 4 Department of Pathophysiology and Transplantation, La Fondazione IRCCS Ca' Granda Ospedale Maggiore di Milano Policlinico, Milano, Lombardia, Italy
  5. 5 Department of Clinical Microbiology Virology and Diagnosis of Bioemergency, Luigi Sacco University Hospital, Milano, Lombardia, Italy
  6. 6 1st Division of Infectious Diseases, Luigi Sacco University Hospital, Milano, Lombardia, Italy
  7. 7 Department of Infectious Diseases, Luigi Sacco University Hospital, Milano, Lombardia, Italy
  8. 8 Unit of Clinical Pathology and Microbiology, University Campus Bio-Medico University of Rome Faculty of Medicine and Surgery, Roma, Lazio, Italy
  1. Correspondence to Dr Alessia Lai, Department of Biomedical and Clinical Sciences L.Sacco, University of Milan, Milano 20157, Italy; alessia.lai{at}


Objectives Transgender people are disproportionately affected by the HIV-1 epidemic. We evaluated the origin of HIV-1 variants carried by South American transgenders living in Milan by combining accurate phylogenetic methods and epidemiological data.

Methods We collected 156 HIV-1 pol sequences obtained from transgender patients engaged in sex work (TSWs) followed between 1999 and 2015 at L. Sacco Hospital, Milan, Italy. Phylogenetic analyses were conducted by HIV-TRACE, MrBayes, MacClade and Beast programs. Reference sequences were retrieved from Los Alamos and local databases. Last negative testing or proxy data from clinical records of infected individuals were used to investigate the country of infection.

Results Among South American TSWs, the most represented HIV-1 subtypes were B (70.5%), F1 (12.8%) and C (4.4%). Gene flow migrations of B subtype indicated significant fluxes from TSWs to Italians (21.3%) belonging to all risk groups (26.4% to heterosexuals (HEs), 18.9% to men who have sex with men (MSM), 15.1% to injecting drug users). The largest proportion of bidirectional fluxes were observed between Italians and TSWs (24.6%). For F1 subtype, bidirectional viral fluxes involved TSWs and Italians (7.1% and 14.3%), and a similar proportion of fluxes linked TSWs and Italian HEs or MSM (both 15.8%). Significant fluxes were detected from Italians to TSWs for subtype C involving both MSM (30%) and HEs (40%). Country of HIV-1 acquisition was identified for 72 subjects; overall, the largest proportion of patients with B subtype (73.5%) acquired HIV-1 infection in South America.

Conclusions Our results indicated that South American transgenders largely contribute to the heterogeneity of HIV-1 variants in our country. The high number of clusters based on all subtypes indicated numerous transmission chains in which TSWs were constantly intermixed with HEs and MSM. Our results strongly advocate interventions to facilitate prevention, diagnosis and HIV-1 care continuum among transgender people.

  • transgender
  • molecular epidemiology
  • HIV

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Handling editor Francesca Ceccherini Silberstein

  • Contributors AL, AB and FRS conceived and designed the study. GB, MF, VM, CA and AR collected and analysed the epidemiological and viral data of patients. GZ and MC participated to phylogenetic analyses. AL, AB, FRS, MG and CB wrote the first draft of the manuscript. All authors contributed to manuscript revision, read and approved the submitted version.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was conducted in accordance with the 1964 Declaration of Helsinki and the ethical standards of the Italian Ministry of Health.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information.