Minimal Transmission of HIV Despite Persistently High Transmission of Hepatitis C Virus in a Swedish Needle Exchange Program

M. Alanko Blomé; P. Björkman; L. Flamholc; H. Jacobsson; V. Molnegren; A. Widell

Disclosures

J Viral Hepat. 2011;18(12):831-839. 

In This Article

Abstract and Introduction

Abstract

The aim of this study was to examine the prevalence and incidence of HIV and hepatitis B and C (HBV and HCV) among injecting drug users in a Swedish needle exchange programme (NEP) and to identify risk factors for blood-borne transmission. A series of serum samples from NEP participants enrolled from 1997 to 2005 were tested for markers of HIV, HBV and HCV (including retrospective testing for HCV RNA in the last anti-HCV-negative sample from each anti-HCV seroconverter). Prevalence and incidence were correlated with self-reported baseline characteristics. Among 831 participants available for follow-up, one was HIV positive at baseline and two seroconverted to anti-HIV during the follow-up of 2433 HIV-negative person-years [incidence 0.08 per 100 person-years at risk (pyr); compared to 0.0 in a previous assessment of the same NEP covering 1990–1993]. The corresponding values for HBV were 3.4/100 pyr (1990–1993: 11.7) and for HCV 38.3/100 pyr (1990–1993: 27.3). HCV seroconversions occurred mostly during the first year after NEP enrolment. Of the 332 cases testing anti-HCV negative at enrolment, 37 were positive for HCV RNA in the same baseline sample (adjusted HCV incidence 31.5/100 pyr). HCV seroconversion during follow-up was significantly associated with mixed injection use of amphetamine and heroin, and a history of incarceration at baseline. In this NEP setting, HIV prevalence and incidence remained low and HBV incidence declined because of vaccination, but transmission of HCV was persistently high. HCV RNA testing in anti-HCV-negative NEP participants led to more accurate identification of timepoints for transmission.

Introduction

Injecting drug use is an important route of HIV transmission worldwide,[1,2] and hence targeting injecting drug users (IDUs) is a priority in HIV prevention. IDUs are also at risk of infection with other blood-borne pathogens, especially hepatitis B virus (HBV) and hepatitis C virus (HCV). Because these viruses share transmission routes, measures taken to prevent HIV might also be expected to reduce the spread of HBV and HCV. A wide range of strategies have been attempted to decrease blood-borne transmission among IDUs, as exemplified by harm reduction interventions such as methadone maintenance therapy (MMT) and needle exchange programmes (NEPs). Although NEPs are recommended by the World Health Organization (WHO), there is no unequivocal evidence from controlled studies demonstrating the protective efficacy of such schemes.[3,4] Most evaluations of the effectiveness of NEPs regarding HIV compare populations or assess injection-related risk behaviour,[5–7] and most studies of virological markers have been cross-sectional.[8,9] HIV incidence studies among NEP participants have in general revealed low rates of seroconversion, especially when NEPs had been initiated before significant spread of HIV occurred in the target population.[10–13] Such results agree with our earlier observations regarding NEP participants in Malmö, Sweden, in 1990–1993.[14] However, a major concern in our Malmö NEP was ongoing transmission of HBV and HCV, which indicated blood-borne transmission despite access to clean injection equipment. We subsequently added HBV immunization to the program, as well as targeted health education concerning the risks of HCV transmission for both HCV-infected and HCV-uninfected participants.

The objective of the present study was to further investigate the recent epidemiology of HIV, HBV and HCV among new participants in the Malmö NEP, which is one of only two such programs in Sweden, and also to determine whether incident HCV infection was linked to baseline drug use–related risk factors.

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