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Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Virol. May 12, 2016; 5(2): 68-72
Published online May 12, 2016. doi: 10.5501/wjv.v5.i2.68
Hepatitis C virus/human T lymphotropic virus 1/2 co-infection: Regional burden and virological outcomes in people who inject drugs
Erika Castro, Elena Roger
Erika Castro, Elena Roger, Addiction Medicine Centre, Service of Community Psychiatry, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois, CH-1003 Lausanne, Switzerland
Author contributions: Castro E and Roger E conceived and designed the study, and performed the literature review and analysis; Castro E wrote the manuscript.
Conflict-of-interest statement: Neither author has any conflict of interest related to the publication of this study.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Erika Castro, MD, PhD, Addiction Medicine Centre, Service of Community Psychiatry, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois, Rue St-Martin 7, CH-1003 Lausanne, Switzerland. erika.castro-bataenjer@chuv.ch
Telephone: +41-21-3148400 Fax: +41-21-3148735
Received: October 8, 2015
Peer-review started: October 8, 2015
First decision: December 4, 2015
Revised: January 9, 2016
Accepted: January 29, 2016
Article in press: January 31, 2016
Published online: May 12, 2016
Abstract

This review analyses current data concerning co-infection with hepatitis C virus (HCV) and human T lymphotropic virus (HTLV)-1/2 in people who inject drugs (PWID), with a particular focus on disease burden and global implications for virological outcome. In addition, the available treatment options for HTLV-1/2 are summarized and the ongoing and likely future research challenges are discussed. The data in this review was obtained from 34 articles on HCV/HTLV-1/2 co-infection in PWID retrieved from the PubMed literature database and published between 1997 and 2015. Despite unavailable estimates of the burden of HCV/HTLV-1/2 co-infection in general, the epidemiologic constellation of HTLV-1/2 shows high incidence in PWID with history of migration, incarceration, and other blood-borne infectious diseases such as HCV or human immunodeficiency virus. The most recent research data strongly suggest that HTLV-1 co-infection can influence HCV viral load, HCV sustained virological response to α-interferon treatment, and HCV-related liver disease progression. In short, outcome of HCV infection is worse in the context of HTLV-1 co-infection, yet more studies are needed to gain accurate estimations of the burden of HCV/HTLV-1/2 co-infections. Moreover, in the current era of new direct-acting antiviral treatments for HCV and proven HTLV-1/2 treatment options, prospective clinical and treatment studies should be carried out, with particular focus on the PWID patient population, with the aim of improving virological outcomes.

Keywords: Hepatitis C virus, Human T lymphotropic virus, Hepatitis C virus/human T lymphotropic virus-1/2 co-infection, People who inject drugs, Human T lymphotropic virus-1/2 screening among people who inject drugs, Co-infection treatment

Core tip: People who inject drugs (PWID) are at higher risk of infection with blood-borne viruses and even co-infections. Co-infections with human immunodeficiency virus and human T lymphotropic virus (HTLV)-1/2 are common, and well-studied, among PWID; however, the rise of HTLV-1/2 co-infections with hepatitis C virus (HCV) has gained much research attention and studies have shown that the former influences the chronic disease course of the latter. This review summarizes the data from 34 articles on HCV/HTLV-1/2 co-infection in the PWID patient population, including current treatment options and impact on virological outcome.