Changes in risk behavior and dynamics of hepatitis C virus infections among young drug users in Amsterdam, the Netherlands

Epidemiology and management of hepatitis B and C in primary care in the Netherlands: data from the Rijnmond Primary Care database

BACKGROUND

The Dutch guideline for general practitioners (GPs) advises biannual surveillance of hepatitis B (HBV) patients and referral of every hepatitis C (HCV) patient. We aimed to study the prevalence, incidence, and the management of hepatitis B and C in primary care.

METHODS

This is a retrospective cohort study using the Rijnmond Primary Care database (RPCD), including health care data of medical records of GPs of approximately 200,000 patients in the area of Rotterdam, the Netherlands. Patient records were selected based on laboratory results, International Classification of Primary Care (ICPC) codes, and free-text words.

RESULTS

In total, 977 patients were included: 717 HBV, 252 HCV, and 8 HBV/HCV coinfected patients. Between 2013 and 2019, the prevalence of HBV and HCV declined from 5.21 to 2.99/1,000 person-years (PYs) and 1.50 to 0.70/1,000 PYs, respectively. We observed that the majority of the patients had been referred to a medical specialist at least once (71% HBV and 89% HCV patients). However, among chronic patients, we observed that 36.2% of the HBV patients did not receive adequate surveillance by their GP (≥2 alanine aminotransferase checks within 3 years) or a medical specialist. In addition, 44.4% of the HCV patients had no record about successful antiviral treatment.

CONCLUSIONS

This study demonstrated a declining prevalence in viral hepatitis B and C in primary care in the Netherlands. However, a substantial part of the patients did not receive adequate surveillance or antiviral therapy. It is therefore crucial to involve GPs in case finding and in follow-up after treatment.

Lessons learned from the Amsterdam Cohort Studies among people who use drugs: a historical perspective

The Netherlands is well known for its early adoption of harm reduction (HR) programs at the height of its heroin crisis in the 1970s/1980s, including the implementation of the first needle and syringe program worldwide. In this manuscript, we describe how the Amsterdam Cohort Studies (ACS) among people who use drugs (PWUD) was conceived within the context of the Dutch HR approach, including the challenges scientists faced while establishing this cohort. This required striking a balance between public health and individual benefit, solving research dilemmas in the face of uncertainty, developing controversial innovative and cutting-edge interventions, which changed the prevention landscape for PWUD, and using longitudinal cohort data to provide unique insights. Studies from the ACS covering follow-up between 1985 and 2016 revealed that participation in both opioid agonist therapy and needle and syringe programs led to a major decrease in the risk of HIV and hepatitis B and C infection acquisition. ACS data have shown that the observed decrease in incidence also likely included shifts in drug markets and drug culture over time, selective mortality among those with the highest levels of risk behaviour, demographic changes of the PWUD population, and progression of the HIV and HCV epidemics. Moreover, HR programs in the Netherlands provided services beyond care for drug use, such as social support and welfare services, likely contributing to its success in curbing the HIV and viral hepatitis epidemics, increasing access and retention to HIV and HCV care and ultimately decreases in overdose mortality over time. Given the low coverage of HR programs in certain regions, it is unsurprising that continued HIV and HCV outbreaks occur and that transmission is ongoing in many countries worldwide. If we aim to reach the World Health Organization viral hepatitis and HIV elimination targets in 2030, as well as to improve the life of PWUD beyond infection risk, comprehensive HR programs need to be integrated as a part of prevention services, as in the Netherlands. We should use the evidence generated by longstanding cohorts, including the ACS, as a basis for which implementation and improved coverage of integrated HR services can be achieved for PWUD worldwide.

Ethical and Practical Issues Associated With the Possibility of Using Controlled Human Infection Trials in Developing a Hepatitis C Virus Vaccine

Despite the existence of established treatments for hepatitis C virus (HCV), more effective means of preventing infection, such as a vaccine, are arguably needed to help reduce substantial global morbidity and mortality. Given the expected challenges of developing such a vaccine among those at heightened risk of infection, controlled human infection studies seem to be a promising potential approach to HCV vaccine development, but they raise substantial ethical and practical concerns. In this article, we describe some of the challenges related to the possibility of using controlled human infection studies to accelerate HCV vaccine development. The related ethical and practical concerns require further deliberation before such studies are planned and implemented.

PROFILE OF HCV GENOTYPES AND HIV-SUBTYPES AMONG HIV-COINFECTED PATIENTS IN SOUTHERN BRAZIL

BACKGROUND

Hepatitis B and C virus (HBV and HCV) are the two most common infections among human immunodeficiency virus (HIV)-infected patients.

OBJECTIVE

To identify the frequency of HIV subtypes and HCV genotypes in HIV-coinfected patients.

METHODS

A cross-sectional and retrospective study was carried out into two reference centers in Southern Brazil between January 1, 2002 and June 30, 2016. The Abbott Real Time HCV Genotype II system was used for routine diagnostics to determine the HCV genotype based on dual-target real-time PCR. Proviral HIV-1 RNA was extracted from serum samples and fragments of the pol gene were generated by PCR. The HIV-1 PT and RT gene sequences were submitted to Maximum Likelihood Phylogenetic analysis by collecting reference sequences from the HIV-1 group M subtype of the Los Alamos database.

RESULTS

During the study period, 3340 patients with HIV were diagnosed at both referral centers, of which 4.97% (166/3340) had HBV and/or HCV coinfection. Seroprevalence of HIV-HBV, HIV-HCV and HIV-HBV-HCV was 37.4%, 58.4%, and 4.2%, respectively. HIV-HCV-coinfected patients had a lower median nadir CD4+ T-cell count when compared to HIV-HBV-coinfected patients (P=0.01). Among those coinfected with HCV, HCV-1 (HCV-1) and HCV-3 (HCV-3) genotypes were the most prevalent, being detected in 73.8% and 21.4%, respectively. Among the HCV-1 coinfected patients, 79.3% and 20.1% had subtypes 1a and 1b, respectively. HIV subtype B was the most prevalent in HIV-coinfected patients. There was no significant difference regarding nadir CD4+ T-cell count and HIV viral load when compared to coinfected with HCV-1 with HCV-3, as well as those co-infected with HCV-1a with HCV-1b.

CONCLUSION

In the present study, a higher frequency of subtype B of HIV and HCV-1 were found in HIV-coinfected patients. Further larger-scale and long-term studies are needed to better understand the effect of HCV genotypes in HIV-infected patients.

Introducing hepatitis C virus healthcare pathways in addiction care in the Netherlands with a Breakthrough project: a mixed method study

Background

People who inject drugs (PWID) are disproportionally affected by the hepatitis C virus (HCV) infection. In the Netherlands, active HCV transmission in PWID has practically been halted but uptake of HCV testing and linkage to care remains insufficient in this risk group. A national HCV in Addiction Care (HAC) quality improvement project based on the Breakthrough methodology (i.e. Breakthrough project) aimed to secure proper linkage to care in PWID by introducing local HCV healthcare screening and treatment pathways in addiction care units.

Aim

To qualitatively appraise the local HCV healthcare pathways; to evaluate the yield in terms of number of PWID screened, diagnosed, referred, and treated; and to identify best practices and barriers to successful participation in the HAC Breakthrough project.

Methods

Between 2013 and 2016, 12 units of addiction care centers throughout the Netherlands participated in two series of a HAC Breakthrough project. Local multidisciplinary teams created HCV healthcare pathways. Quality assessment of HCV healthcare pathways was performed retrospectively and data on screening results was collected. In-depth interviews were conducted to elucidate best practices and essential elements for successful participation.

Results

In total, six HCV healthcare pathways were submitted by ten teams of which 83% was judged to be of “good” or “sufficient” quality. Uptake of HCV-antibody screening was 40% (N = 487/1219) and uptake of HCV-RNA in HCV-antibody positives was 59% (N = 107/181). The project resulted in 76 (6%) newly detected cases of persistent HCV viremia. Of all HCV-RNA positives, 92% was referred to a hepatitis treatment center. In 39% (N = 27/70) of those referred, treatment initiation was documented and 82% (N = 22/27) achieved a sustained virological response. Teams identified several best practices including motivational counseling training, oral swabs for anti-HCV testing, facilitating complementary HCV RNA testing, and supervised hospital visits.

Conclusion

The HAC Breakthrough project has brought about good quality HCV healthcare pathways in the majority of participating addiction care centers and has successfully linked PWID with ongoing HCV viremia to care. Uptake of HCV screening and treatment after referral were identified as the main gaps to be closed in the HCV cascade of care to achieve final HCV elimination in Dutch PWID (i.e. micro-elimination).

Strategies for achieving viral hepatitis C micro-elimination in the Netherlands

The Netherlands is striving to achieve national elimination of the hepatitis C virus (HCV) as one of the first countries worldwide. The favorable HCV epidemiology with both low prevalence and incidence, together with access to care and treatment, present excellent conditions to further build on towards this objective. The Dutch national plan on viral hepatitis, introduced in 2016, defines targets in the HCV healthcare cascade and provides a structural framework for the development of elimination activities. Since many different stakeholders are involved in HCV care in the Netherlands, focus has been placed on micro-elimination initiatives as a pragmatic and efficient approach. These numerous micro-eliminations projects have brought the Netherlands closer to HCV elimination. In the near future, efforts specifically have to be made in order to optimize case-finding strategies and to successfully accomplish the nationwide implementation of the registration and monitoring system of viral hepatitis mono-infections, before this final goal can be reached. The upcoming years will then elucidate if the Dutch' hands on approach has resulted in sufficient progress against HCV and if the Netherlands will lead the way towards nationwide HCV elimination.

Drug consumption rooms (DCRs) as a setting to address hepatitis C - findings from an international online survey

BACKGROUND

Prevalence of Hepatitis C Virus (HCV) among people who inject drugs (PWID) is high. Risky injecting behaviours have been found to decrease in drug consumption rooms (DCRs) and supervised injecting facilities (SIFs), yet HCV prevention and treatment in these settings have not been extensively explored.

METHODS

To determine the range and scope of HCV prevention and treatment options in these services, we assessed DCR/SIF operational features, their clients' characteristics and the HCV-related services they provide. A comprehensive online survey was sent to the managers of the 91 DCRs/SIFs that were operating globally as of September 2016. A descriptive cross-country analysis of the main DCR/SIF characteristics was conducted and bivariate logistic models were used to assess factors associated with enhanced HCV service provision.

RESULTS

Forty-nine valid responses were retrieved from DCRs/SIFs in all countries where they were established at the time of the survey (Australia, Canada, Denmark, France, Germany, Luxembourg, Netherlands, Norway, Spain and Switzerland). Internationally, the operational capacities of DCRs/SIFs varied in terms of funding, location, size and staffing, but their clients all shared common features of vulnerability and marginalisation. Estimated HCV prevalence rates were around 60%. Among a range of health and social services and referrals to other programs, most DCRs/SIFs provided HCV testing onsite (65%) and/or offered liver monitoring or disease management (54%). HCV treatment onsite was offered or was planned to be offered by 21% of DCRs/SIFs. HCV testing onsite was associated with provision of other services addressing blood-borne diseases and HCV treatment was linked to the provision of OST. HCV disease management was associated with employing a nurse at a DCR/SIF and HCV treatment was associated with employing a medical doctor.

CONCLUSIONS

DCRs/SIFs offer easy-to-access HCV-related services for PWID. The availability of onsite medical professionals and provision of support and education to non-medical staff are key to enhanced provision of HCV-related services in DCRs/SIFs. Funding and support for HCV treatment at the community level, via low-threshold services such as DCRs/SIFs, are worthy of action.

Phylogenetic analysis of an epidemic outbreak of acute hepatitis C in HIV-infected patients by ultra-deep pyrosequencing

BACKGROUND

The incidence of acute hepatitis C (AHC) among HIV-infected men who have sex with men (MSM) has increased significantly in the last 10 years. Several studies point to a social and sexual network of HIV-positive MSM that extends internationally.

OBJECTIVES

The aim of our study was to investigate the dynamics of HCV transmission in an outbreak of AHC in HIV-infected MSM in Barcelona by ultra-deep pyrosequencing.

STUDY DESIGN

Between 2008 and 2013, 113 cases of AHC in HIV-infected MSM were diagnosed in the Infectious Diseases Unit, Hospital Clínic, Barcelona. Massive sequencing was performed using the Roche 454 GS Junior platform. To define possible transmission networks, maximum likelihood phylogenetic trees were constructed, and levels of genetic diversity within and among patients were compared.

RESULTS

Among the 70 cases analyzed, we have identified 16 potential clusters of transmission: 8 for genotype 1a (23 cases involved), 1 for genotype 1b (3 cases) and 7 for genotype 4d (27 cases). Although the initial phylogenetic reconstruction suggested a local transmission cluster of HCV gt4d, our approach based on low genetic differentiation did not corroborate it. Indeed, gt4d strains formed 4 independent groups related to patients from other countries.

CONCLUSIONS

Frequent clustering of HIV-positive MSM shows that HCV infection has spread through a local network in Barcelona. This outbreak is related to a large international HCV transmission network among MSM. Public health efforts are needed to reduce HCV transmission among this high-risk group.

Cost-Effectiveness of Hepatitis C Treatment for People Who Inject Drugs and the Impact of the Type of Epidemic; Extrapolating from Amsterdam, the Netherlands

BACKGROUND

People who inject drugs (PWID) are disproportionally affected by the hepatitis C virus (HCV) infection. The efficacy of HCV treatment has significantly improved in recent years with the introduction of direct-acting antivirals (DAAs). However, DAAs are more costly than pegylated-interferon and ribavirin (PegIFN/RBV). We aimed to assess the cost-effectiveness of four HCV treatment strategies among PWID and treatment scale-up.

METHODS

An individual-based model was used describing HIV and HCV transmission and disease progression among PWID. We considered two epidemiological situations. A declining epidemic, based on the situation in Amsterdam, the Netherlands, and a stable HCV epidemic, as observed in other settings. Data on HCV incidence, prevalence, treatment setting and uptake were derived from observed data among PWID in Amsterdam. We assessed the incremental cost-effectiveness ratio (ICER, costs in €/quality-adjusted life year (QALY)) of four treatment strategies: 1) PegIFN/RBV; 2) sofosbuvir/RBV for genotype 2-3 and dual DAA for genotype 1-4; 3) Dual DAA for all genotypes; 4) Dual DAA with 3x treatment uptake.

RESULTS

In both types of epidemic, dual DAA therapy was most cost-effective strategy. In the declining epidemic, dual DAA yielded an ICER of 344 €/QALY while in the stable epidemic dual DAA led to cost-savings. Scaling-up treatment was also highly cost-effective. Our results were robust over a range of sensitivity analyses.

CONCLUSION

HCV treatment with DAA-containing regimens is a highly cost-effective intervention among PWID. Based on the economic and population benefits of scaling-up treatment, stronger efforts are needed to achieve higher uptake rates among PWID.

Hepatitis C Virus Reinfection and Spontaneous Clearance of Reinfection--the InC3 Study

BACKGROUND

We aimed to characterize the natural history of hepatitis C virus (HCV) reinfection and spontaneous clearance following reinfection (reclearance), including predictors of HCV reclearance.

METHODS

Data were synthesized from the 9 prospective cohorts of the International Collaboration of Incident Human Immunodeficiency Virus and HCV in Injecting Cohorts study, which evaluated HCV infection outcomes among people who inject drugs. Participants with primary HCV infection were classified as having achieved viral suppression if they had negative results of at least 1 subsequent HCV RNA test. Those with positive results of an HCV RNA test following viral suppression were investigated for reinfection. Viral sequence analysis was used to identify reinfection (defined as detection of heterologous virus with no subsequent detection of the original viral strain).

RESULTS

Among 591 participants with acute primary HCV infection, 118 were investigated for reinfection. Twenty-eight participants were reinfected (12.3 cases/100 person-years; 95% confidence interval [CI], 8.5-17.8). Peak HCV RNA level was lower during reinfection than primary infection (P = .011). The proportion of individuals with reclearance 6 months after reinfection was 52% (95% CI, 33%-73%). After adjustment for study site, females with the IFNL4 (formerly IFNL3 and IL28B) rs12979860 CC genotype detected were more likely to have reclearance (hazard ratio, 4.16; 95% CI, 1.24-13.94; P = .021).

CONCLUSIONS

Sex and IFNL4 genotype are associated with spontaneous clearance after reinfection.

Exploration of genetically determined resistance against hepatitis C infection in high-risk injecting drug users

Genetic resistance to specific infections is well recognized. In hepatitis C virus (HCV) infection, genetic polymorphisms in IL-28B and the killer cell immunoglobulin-like receptors (KIR) and their HLA class I ligands have been shown to affect clearance of the virus following infection. There are limited data regarding resistance to established HCV infection. Reliable quantification of repeated exposure in high-risk populations, such as injecting drug users (IDU), is a key limitation of previous studies of resistance. Behavioural data and DNA from IDU (n = 210) in the Hepatitis C Incidence and Transmission Study in prisons (HITS-p) cohort were genotyped for polymorphisms in: IL-28B, peptidyl-prolyl isomerase A (PPIA), HLA-C and KIR2. To quantify risk, a composite risk index based on factors predictive of incident HCV infection was derived. Logistic regression analysis revealed the risk index was strongly associated with incident HCV infection (P < 0.0001). The upper tertile of the uninfected individuals had risk indices comparable to the incident cases, but remained uninfected. There were no significant differences in the frequencies of IL-28B or PPIA polymorphisms between these exposed-uninfected cases, or in the frequencies of KIR2-DL3, HLA-C1, or their combination. A framework for the investigation of genetic determinants of resistance to HCV infection has been developed. Several candidate gene associations were investigated and excluded. Further investigation of genetic determinants of resistance to HCV infection is warranted.

Hepatitis C virus infection epidemiology among people who inject drugs in Europe: a systematic review of data for scaling up treatment and prevention

BACKGROUND

People who inject drugs (PWID) are a key population affected by hepatitis C virus (HCV). Treatment options are improving and may enhance prevention; however access for PWID may be poor. The availability in the literature of information on seven main topic areas (incidence, chronicity, genotypes, HIV co-infection, diagnosis and treatment uptake, and burden of disease) to guide HCV treatment and prevention scale-up for PWID in the 27 countries of the European Union is systematically reviewed.

METHODS AND FINDINGS

We searched MEDLINE, EMBASE and Cochrane Library for publications between 1 January 2000 and 31 December 2012, with a search strategy of general keywords regarding viral hepatitis, substance abuse and geographic scope, as well as topic-specific keywords. Additional articles were found through structured email consultations with a large European expert network. Data availability was highly variable and important limitations existed in comparability and representativeness. Nine of 27 countries had data on HCV incidence among PWID, which was often high (2.7-66/100 person-years, median 13, Interquartile range (IQR) 8.7-28). Most common HCV genotypes were G1 and G3; however, G4 may be increasing, while the proportion of traditionally 'difficult to treat' genotypes (G1+G4) showed large variation (median 53, IQR 43-62). Twelve countries reported on HCV chronicity (median 72, IQR 64-81) and 22 on HIV prevalence in HCV-infected PWID (median 3.9%, IQR 0.2-28). Undiagnosed infection, assessed in five countries, was high (median 49%, IQR 38-64), while of those diagnosed, the proportion entering treatment was low (median 9.5%, IQR 3.5-15). Burden of disease, where assessed, was high and will rise in the next decade.

CONCLUSION

Key data on HCV epidemiology, care and disease burden among PWID in Europe are sparse but suggest many undiagnosed infections and poor treatment uptake. Stronger efforts are needed to improve data availability to guide an increase in HCV treatment among PWID.

Trends in hepatitis C virus infections among MSM attending a sexually transmitted infection clinic; 1995-2010

BACKGROUND

Since 2000, there is growing evidence that hepatitis C virus (HCV) infection has emerged as a sexually transmitted infection (STI) among HIV-positive MSM. Here, we present a 15-year overview of the HCV epidemic among MSM visiting a large STI-clinic in the Netherlands.

METHODS

During biannual cross-sectional anonymous surveys (1995-2010), participants were interviewed and tested for HIV and HCV-antibodies. Additional HCV RNA tests were performed in all HIV-positives. Determinants of HCV infection were analysed using logistic regression. Phylogenetic analysis provided evidence for sexual transmission.

RESULTS

HCV prevalence among HIV-positive MSM increased from 1995 onwards (5.6%) and peaked in 2008 (20.9%). Prevalent HCV infection was more strongly associated with fisting in 2007-2008 [adjusted odds ratio (aOR) 2.85, 95% confidence interval (CI) 1.19-6.82] than in 2009-2010 (aOR 0.92, 95% CI0.42-2.02). In addition, HCV infection was independently associated with Chlamydia, injecting drug use, unprotected anal intercourse and older age. Phylogenetic analysis revealed a high degree of MSM-specific clustering from 2000 onwards. Identification of a new MSM-specific HCV lineage and the finding of recent HCV infections (0-4%) in established HCV clusters during recent years argue for ongoing transmission of HCV among HIV-positive MSM. HCV prevalence among HIV-negative MSM remained low (2007-2010: 0.5%).

CONCLUSION

HCV prevalence among HIV-positive MSM significantly increased over calendar time but appears to level off in recent years, possibly due to increased awareness, saturation in the population, decreased risk behaviour and earlier HCV screening and treatment. The association with fisting became less strong over time, but our analyses continue to support sexual transmission. Monitoring HIV-positive and HIV-negative MSM for HCV infection remains needed to guide prevention efforts.

Drug users in Amsterdam: are they still at risk for HIV?

Background and Aims

To examine whether drug users (DU) in the Amsterdam Cohort Study (ACS) are still at risk for HIV, we studied trends in HIV incidence and injecting and sexual risk behaviour from 1986 to 2011.

Methods

The ACS is an open, prospective cohort study on HIV. Calendar time trends in HIV incidence were modelled using Poisson regression. Trends in risk behaviour were modelled via generalized estimating equations. In 2010, a screening for STI (chlamydia, gonorrhoea and syphilis) was performed. Determinants of unprotected sex were studied using logistic regression analysis.

Results

The HIV incidence among 1298 participants of the ACS with a total follow-up of 12,921 person-years (PY) declined from 6.0/100 PY (95% confidence interval [CI] 3.2–11.1) in 1986 to less than 1/100 PY from 1997 onwards. Both injection and sexual risk behaviour declined significantly over time. Out of 197 participants screened for STI in 2010–2011, median age 49 years (IQR 43–59), only 5 (2.5%) were diagnosed with an STI. In multivariable analysis, having a steady partner (aOR 4.1, 95% CI 1.6–10.5) was associated with unprotected sex. HIV-infected participants were less likely to report unprotected sex (aOR 0.07, 95% CI 0.02–0.37).

Conclusions

HIV incidence and injection risk behaviour declined from 1986 onwards. STI prevalence is low; unprotected sex is associated with steady partners and is less common among HIV-infected participants. These findings indicate a low transmission risk of HIV and STI, which suggests that DU do not play a significant role in the current spread of HIV in Amsterdam.

Hepatitis C virus prevalence in The Netherlands: migrants account for most infections

A population-based anti-hepatitis C virus (HCV) prevalence is important for surveillance purposes and it provides insight into the burden of disease. The outcomes of recent studies in the general Dutch population as well as recent HCV data from specific risk groups including migrants, men who have sex with men (MSM) and injecting drug users (IDUs), were implemented in a modified version of the Workbook Method (a spreadsheet originally designed for HIV estimations), to estimate Dutch HCV seroprevalence. The estimated national seroprevalence of HCV was 0·22% (min 0·07%, max 0·37%), corresponding to 28 100 (min n = 9600, max n = 48 000) HCV-infected individuals in The Netherlands. Of these, first-generation migrants from HCV-endemic countries (HCV prevalence ≥2%) accounted for the largest HCV-infected group, followed by IDUs and HIV-positive MSM.

Colonial history and contemporary transmission shape the genetic diversity of hepatitis C virus genotype 2 in Amsterdam

Evolutionary analysis of hepatitis C virus (HCV) genome sequences has provided insights into the epidemic history and transmission of this widespread human pathogen. Here we report an exceptionally diverse set of 178 HCV genotype 2 (HCV-2) isolates from 189 patients in Amsterdam, comprising 8 distinct HCV subtypes and 10 previously not recognized, unclassified lineages. By combining study subjects' demographic information with phylogeographic and molecular clock analyses, we demonstrate for the first time that the trans-Atlantic slave trade and colonial history were the driving forces behind the global dissemination of HCV-2. We detect multiple HCV-2 movements from present-day Ghana/Benin to the Caribbean during the peak years of the slave trade (1700 to 1850) and extensive transfer of HCV-2 among the Netherlands and its former colonies Indonesia and Surinam over the last 150 years. The latter coincides with the bidirectional migration of Javanese workers between Indonesia and Surinam and subsequent immigration to the Netherlands. In addition, our study sheds light on contemporary trends in HCV transmission within the Netherlands. We observe multiple lineages of the epidemic subtypes 2a, 2b, and 2c (together 67% of HCV-2 infections in Amsterdam), which cluster according to their suspected routes of transmission, specifically, injecting drug use (IDU) and contaminated blood/blood products. Understanding the epidemiological processes that generated the global pattern of HCV diversity seen today is critical for exposing associations between populations, risk factors, and specific HCV subtypes and might help HCV screening and prevention campaigns to minimize the future burden of HCV-related liver disease.

Case report: risk of virus infection after accidental blood inoculation from a multi-infected AIDS patient

Infections caused by blood-borne viruses such as hepatitis B and C and the human immunodeficiency virus (HIV) are associated commonly with needlestick injuries, especially in a hospital setting. A prospective investigation was conducted on a medical doctor who suffered an accidental needlestick injury during blood collection from a patient with AIDS. The patient's blood contained 195,000 copies of HIV RNA, 1 × 10(6) IU hepatitis C virus (HCV) RNA, and >10(7) copies of parvovirus B19 DNA per 1 ml plasma. It was positive for cytomegalovirus virus and evidence of a resolved hepatitis B virus (HBV) infection was found. HCV viremia was detected in the physician 15 days later and was not resolved by seroconversion after 57 days. HIV infection was not transmitted, possibly because of the immediate use of anti-HIV prophylactic drugs after exposure. Parvovirus B19 infection was presumably prevented by pre-existing specific antibodies in the patient. Considering that many HIV carriers are coinfected with hepatitis B and C viruses, this case report support the knowledge that the risk of HCV transmission from a patient with AIDS is greater than that of HIV.

Hepatitis C virus seroprevalence in the Netherlands

A population-based anti-hepatitis C virus (HCV) prevalence is important for surveillance purposes and it provides an insight into the burden of disease. In The Netherlands, a recent HCV seroprevalence estimate is not available. This national population-based cross-sectional serosurvey (PIENTER-2) resulted in a weighted national HCV seroprevalence of 0.30% (95% confidence interval 0.05-0.55%). About 70% of the HCV positive individuals found were born in an HCV-endemic country.

Hepatitis C in the general population of various ethnic origins living in the Netherlands: should non-Western migrants be screened?

BACKGROUND & AIMS

Little is known about the HCV prevalence in non-Western migrant populations. To determine whether targeted HCV screening and prevention programs for migrants are needed, we examined HCV prevalence and determinants among non-Western, Western migrants, and the native Dutch population in the Netherlands.

METHODS

Data were obtained from four surveys: (1) 3895 heterosexual visitors recruited during biannual surveys at the STI-clinic Amsterdam, 2007-2009; (2) random sample of 4563 pregnant women in Amsterdam, 2003; (3) population-based random sample of 1309 inhabitants of Amsterdam, 2004; (4) population-based random sample of 4428 people living in the Netherlands, 2006-2007. Characteristics associated with HCV-positivity were examined and phylogenetic analysis was used to obtain insight in the geographical origin of HCV strains.

RESULTS

HCV seroprevalence in the four surveys was low (0.3-0.6%). In total 4860/14,195 (34%) were non-Western and 9329/14,195 (66%) Western participants (including Dutch). First-generation non-Western migrants were more likely to be HCV-positive (0.7-2.3%) than Western participants (0.1-0.4%). Except for survey 3, second-generation non-Western migrants had a lower HCV prevalence than first-generation migrants, comparable to Western migrants and the Dutch population. Phylogenetic analysis showed that the majority of the HCV-positive, first-generation non-Western non-European migrants were infected with endemic strains which are rarely observed in Europe.

CONCLUSIONS

First-generation non-Western migrants are at increased risk for HCV. Phylogenetic analysis suggests that transmission likely took place in the country of origin, causing introduction but no further transmission of endemic HCV strains in the Netherlands. HCV screening and prevention programs should target first-generation, but not second-generation, non-Western migrants.

Estimating the force of infection for HCV in injecting drug users using interval-censored data

Injecting drug users (IDUs) account for most new HCV infections. The objectives of this study were: to estimate the force of infection for hepatitis C virus in IDUs within the interval-censoring framework and to determine the impact of risk factors such as frequency of injection, drug injected, sharing of syringes and time of first injection on the time to HCV infection. We used data from the Amsterdam Cohort Study collected in The Netherlands and focused on those individuals who were HCV negative upon entry into the study. Based on the results, the force of infection was found to vary with time of first injection. The risk of infection was higher in the first 3 years of an IDU's career, implying estimates based on single cross-sectional studies could be biased. Frequency of injection and type of drug injected were found to be highly significant predictors, whereas sharing syringes was not.

A systematic review and meta-analysis of interventions to prevent hepatitis C virus infection in people who inject drugs

INTRODUCTION

High rates of hepatitis C virus (HCV) transmission are found in samples of people who inject drugs (PWID) throughout the world. The objective of this paper was to meta-analyze the effects of risk-reduction interventions on HCV seroconversion and identify the most effective intervention types.

METHODS

We performed a systematic review and meta-analysis of published and unpublished studies. Eligible studies reported on the association between participation in interventions intended to reduce unsafe drug injection and HCV seroconversion in samples of PWID.

RESULTS

The meta-analysis included 26 eligible studies of behavioral interventions, substance-use treatment, syringe access, syringe disinfection, and multicomponent interventions. Interventions using multiple combined strategies reduced risk of seroconversion by 75% (pooled relative risk, .25; 95% confidence interval, .07-.83). Effects of single-method interventions ranged from .6 to 1.6.

CONCLUSIONS

Interventions using strategies that combined substance-use treatment and support for safe injection were most effective at reducing HCV seroconversion. Determining the effective dose and combination of interventions for specific subgroups of PWID is a research priority. However, our meta-analysis shows that HCV infection can be prevented in PWID.

Hepatitis C virus subtypes circulating among intravenous drug users in Lisbon, Portugal

Hepatitis C virus (HCV) infects 2-3% of the world population and intravenous drug consumption is the leading cause of transmission in industrialized countries. The unavailability of data on the molecular epidemiology of HCV infection in Portugal prompted the study of HCV subtypes circulating among intravenous drug users residing in the Lisbon metropolitan area and sampled about 10 years apart (1998-2000 and 2008-2009). Partial coding sequences for E1 and/or NS5B were obtained from 124 individuals with HCV viremia, both mono-infected and co-infected with HIV. Phylogenetic analysis showed that, for both time periods, the most prevalent subtypes were 1a and 3a, found, altogether, in 64.9% and 71.6% of the individuals, respectively for the first and the second sampling periods. However, genotype 4 viruses (subtypes 4a and 4d), introduced later, as inferred by comparison of intra-subtype genetic distances, were also relatively frequent even one decade ago (24.6%). This HCV subtype profile for Portuguese intravenous drug users is in agreement with those described for other southern European countries when in association with drug consumption. With the exception of subtype 1b, phylogenetic trees did not show clustering of the Portuguese sequences, but rather phylogenetic mixing of HCV sequences from different geographic origins, as described previously in other Western countries and suggestive of a large international transmission network. Consistent with the low recombination rates reported for HCV, only one sample revealed discordant subtypes for the two regions analyzed (4d in E1 and 4a in NS5B), representing a potential new recombinant that deserves further analysis.

Hepatic and extra-hepatic sequelae, and prevalence of viral hepatitis C infection estimated from routine data in at-risk groups

Background

Concerns about the hepatitis C virus (HCV) are due to the high risk of chronic liver disease and poor treatment efficacy. Synthesizing evidence from multiple data sources is becoming widely used to estimate HCV-infection prevalence. This paper aims to estimate the prevalence of HCV infection, and the hepatic and extrahepatic sequelae in at-risk groups, using routinely collected data in the Lazio region, Italy.

Methods

HCV laboratory surveillance and dialysis, hospital discharge, and drug-user registers were used as information sources to identify at-risk groups and to estimate HCV prevalence and sequelae.

Full name and birth date were used as linkage keys for the various health registries. Prevalence was estimated as the percentage of cases within the general population and the at-risk groups, with 95% confidence intervals (95% CI) from 1997 to 2001. The risk of sequelae was estimated through a follow-up of hospital discharges up to December 31, 2004 and calculated as the prevalence ratio in HCV-positive and HCV-negative people, within each at-risk group, with 95% CI.

Results

There were 65,127 HCV-infected people in the study period; the prevalence was 1.24% (95%CI = 1.23%-1.25%) in the whole population, higher in males and older adults. Drug users (35.1%; 95%CI = 34.6-35.7) and dialysis patients (21.1%; 95%CI = 20.2%-22.0%) showed the highest values. Medical procedures with little exposure to blood resulted in higher estimates, ranging between 1.3% and 3.4%, which was not conclusively attributable to the surgical procedures. Cirrhosis, hepatocellular carcinoma and encephalopathy were the most frequent hepatic sequelae; cryoglobulinaemia and non-Hodgkin's lymphoma were the most frequent extrahepatic sequelae.

Conclusions

Synthesising data from multiple routine sources improved estimates of HCV prevalence and sequelae in dialysis patients and drug users, although prevalence validity should be assessed in survey and sequelae need a well-defined longitudinal approach.

Hepatitis C infection among intravenous drug users attending therapy programs in Cyprus

The most high-risk population for HCV transmission worldwide today are intravenous drug users. HCV genotypes in the general population in Cyprus demonstrate a polyphyletic infection and include subtypes associated with intravenous drug users. The prevalence of HCV, HBV, and HIV infection, HCV genotypes and risk factors among intravenous drug users in Cyprus were investigated here for the first time. Blood samples and interviews were obtained from 40 consenting users in treatment centers, and were tested for HCV, HBV, and HIV antibodies. On the HCV-positive samples, viral RNA extraction, RT-PCR and sequencing were performed. Phylogenetic analysis determined subtype and any relationships with database sequences and statistical analysis determined any correlation of risk factors with HCV infection. The prevalence of HCV infection was 50%, but no HBV or HIV infections were found. Of the PCR-positive samples, eight (57%) were genotype 3a, and six (43%) were 1b. No other subtypes, recombinant strains or mixed infections were observed. The phylogenetic analysis of the injecting drug users' strains against database sequences observed no clustering, which does not allow determination of transmission route, possibly due to a limitation of sequences in the database. However, three clusters were discovered among the drug users' sequences, revealing small groups who possibly share injecting equipment. Statistical analysis showed the risk factor associated with HCV infection is drug use duration. Overall, the polyphyletic nature of HCV infection in Cyprus is confirmed, but the transmission route remains unknown. These findings highlight the need for harm-reduction strategies to reduce HCV transmission.

Serosorting for hepatitis C status in the sharing of injection equipment among Seattle area injection drug users

BACKGROUND

Hepatitis C virus (HCV) is a major health problem among injection drug users (IDU). One potential means of reducing risk of HCV transmission among IDU is serosorting, whereby IDU preferentially share injection equipment with persons of like HCV status.

METHODS

We surveyed Seattle area IDU recruited by respondent-driven sampling as part of the National HIV/AIDS Behavioral Surveillance system in 2005.

RESULTS

Of 337 participants, 91% reported ever having been tested for HCV. Fifty-three percent of participants who shared any injection equipment in the last 12 months reported knowing the HCV status of the last person with whom they shared injection equipment. Thirty-seven percent of self-reported HCV-positive participants reported that their last injection equipment sharing partner was also HCV-positive and 7% reported a HCV-negative partner. Among self-reported HCV-negative participants, 11% reported a HCV-positive partner and 23% a negative partner. The disproportionate tendency to share injection equipment with a partner of like HCV status persisted after control for characteristics associated with HCV positivity in stratified and logistic regression analyses. Among participants sharing injection equipment, 39% reported that they had intentionally shared injection equipment with a partner based on knowledge of their concordant HCV status.

CONCLUSIONS

We conclude that a measurable degree of serosorting by HCV status is occurring among Seattle area IDU. Promotion of serosorting among HCV-positive IDU may be a useful harm reduction strategy for IDU who continue to practice sharing injection equipment. If judged efficacious, serosorting would provide a further rationale to encourage and support HCV testing among IDU.

Frequent HCV reinfection and superinfection in a cohort of injecting drug users in Amsterdam

BACKGROUND/AIMS

This study investigates the occurrence of HCV reinfection and superinfection among HCV seroconverters participating in the Amsterdam Cohort Studies among drug users from 1985 through 2005.

METHODS

HCV seroconverters (n=59) were tested for HCV RNA at five different time points: the last visit before seroconversion (t=-1), the first visit after seroconversion (t=1), six months after (t=2) and one year after (t=3) seroconversion, and the last visit prior to November 2005 (t=4). If HCV RNA was present, part of the NS5B region was amplified and sequenced. Additional phylogenetic analysis and cloning was performed to establish HCV reinfection and superinfection.

RESULTS

Multiple HCV infections were detected in 23/59 (39%) seroconverters; 7 had HCV reinfections, 14 were superinfected, and 2 had reinfection followed by superinfection. At the moment of HCV reinfection, 7/9 seroconverters were HIV-negative: persistent HCV reinfection developed in both HIV-positive cases but also in 4/7 HIV-negative cases. In total, we identified 93 different HCV infections, varying from 1 to 4 infections per seroconverter. Multiple HCV infections were observed in 10/24 seroconverters with spontaneous HCV clearance (11 reinfections, 3 superinfections) and in 13/35 seroconverters without viral clearance (20 superinfections).

CONCLUSIONS

HCV reinfection and superinfection are common among actively injecting drug users. This might further complicate the development of an effective HCV vaccine.

Emergence of hepatitis C virus genotype 4: phylogenetic analysis reveals three distinct epidemiological profiles

Hepatitis C virus (HCV) genotype 4 (HCV-4) infection is considered to be difficult to treat and has become increasingly prevalent in European countries, including The Netherlands. Using a molecular epidemiological approach, the present study investigates the genetic diversity and evolutionary origin of HCV-4 in Amsterdam, The Netherlands. Phylogenetic analysis of the NS5B sequences (668 bp) obtained from 133 patients newly diagnosed with HCV-4 infection over the period from 1999 to 2008 revealed eight distinct HCV-4 subtypes; the majority of HCV-4 isolates were of subtypes 4d (57%) and 4a (37%). Three distinct monophyletic clusters were identified, with each one having a specific epidemiological profile: (i) Egyptian immigrants infected with HCV-4a (n = 46), (ii) Dutch patients with a history of injecting drug use infected with HCV-4d (n = 44), and (iii) Dutch human immunodeficiency virus (HIV)-positive men who have sex with men (MSM) infected with HCV-4d (n = 26). Subsequent molecular clock analyses confirmed that the emergence of HCV-4 within these three risk groups coincided with (i) the parenteral antischistosomal therapy campaigns in Egypt (1920 to 1960), (ii) the popularity of injecting drug use in The Netherlands (1960 to 1990), and (iii) the rise in high-risk sexual behavior among MSM after the introduction of highly active antiretroviral therapy (1996 onwards). Our data show that in addition to the influx of HCV-4 strains from countries where HCV-4 is endemic, the local spread of HCV-4d affecting injecting drug users and, in recent years, especially HIV-positive MSM will further increase the relative proportion of HCV-4-infected patients in The Netherlands. HCV-4-specific agents are drastically needed to improve treatment response rates and decrease the future burden of HCV-4-related disease.

Never injected, but hepatitis C virus-infected: a study among self-declared never-injecting drug users from the Amsterdam Cohort Studies

The aim of this study was to gain insight in transmission routes of hepatitis C virus (HCV) infection among never-injecting drug users (DU) by studying, incidence, prevalence, determinants and molecular epidemiology of HCV infection. From the Amsterdam Cohort Studies among DU, 352 never-injecting DU were longitudinally tested for HCV antibodies. Logistic regression was used to identify factors associated with antibody prevalence. Part of HCV NS5B was sequenced to determine HCV genotype and for phylogenetic analyses, in which sequences were compared with those from injecting DU. HCV antibody prevalence was 6.3% and HCV incidence was 0.49/1000 PY. HIV-positive status, female sex and starting injection drug use during follow-up (a putative marker of past injection drug use), were independently associated with HCV prevalence. The main genotypes found were genotype 3a (50%) and 1a (30%). Phylogenetic analysis revealed that HCV strains in never-injecting DU did not cluster together and did not differ from HCV strains circulating in injecting DU. We found a higher HCV prevalence in never-injecting DU than in the general population. Phylogenetic analysis shows a strong link with the injecting DU population. The increased risk could be related to underreporting of injecting drug use or to household or sexual transmission from injectors to noninjectors. Our findings stress the need for HCV testing of DU who report never injecting, especially given the potential to treat HCV infection effectively.

Hepatitis C virus infections among HIV-infected men who have sex with men: an expanding epidemic

BACKGROUND

Since 2000 outbreaks of sexually transmitted hepatitis C Virus (HCV) infections have been reported among HIV-infected men who have sex with men (MSM). We studied the prevalence and determinants of HCV-infection among MSM attending a large sexually transmitted infection (STI) clinic in the Netherlands.

METHODS

In 2007-2008, 3125 attendees of the STI clinic Amsterdam, including 689 MSM, participated in an anonymous biannual crosssectional survey. Participants were interviewed and screened for HIV and HCV antibodies. Additionally, all anti-HCV positive and HIV-infected individuals were tested for HCV RNA. Using phylogenetic analysis, HCV strains of the STI clinic attendees were compared with those isolated from MSM with acute HCV in 2000-2007. Determinants of HCV-infection were analysed using logistic regression.

RESULTS

Two of 532 (0.4%) HIV-negative MSM and 28 of 157 (17.8%) HIV-positive MSM were infected with HCV. Over the study period, HCV prevalence among HIV-infected MSM increased (14.6%-20.9%). Seven of 28 (25.0%) HIV/HCV coinfected MSM had acute HCV infection. Only five of 28 (17.9%) HIV/HCV coinfected MSM ever injected drugs (IDU). HIV-infection, IDU, fisting and gamma hydroxy butyrate (GHB)-use were significantly associated with HCV-infection. Phylogenetic analyses revealed a high degree of MSM-specific clustering.

CONCLUSION

We found a high and increasing HCV prevalence in HIV-infected MSM. Though not statistically significant, this trend, and the relatively large proportion of acute infections suggest ongoing transmission of HCV in HIV-positive MSM. Regardless of IDU, rough sexual techniques and use of recreational drugs were associated with HCV-infection; phylogenetic analysis supported sexual transmission. Targeted prevention, like raising awareness and routine testing, is needed to stop the further spread among HIV-infected MSM, and to prevent possible spillover to HIV-negative MSM.

Evidence of a large, international network of HCV transmission in HIV-positive men who have sex with men

BACKGROUND & AIMS

Since 2000, there has been a marked rise in acute hepatitis C virus (HCV) in human immunodeficiency virus (HIV)-positive men who have sex with men (MSM). We conducted an international phylogenetic study to investigate the existence of an HCV transmission network among MSM.

METHODS

HIV-positive MSM diagnosed with recent HCV (n = 226) in England (107), The Netherlands (58), France (12), Germany (25), and Australia (24) between 2000 and 2006 were enrolled into a molecular phylogenetic study. Using real-time polymerase chain reaction (PCR), the NS5B region of the HCV genome (436 base pair) was amplified, sequenced, and compared with unrelated NS5B sequences.

RESULTS

NS5B sequences were obtained from 200 (89%) cases. Circulating HCV genotypes were 1a (59%), 4d (23%), 3a (11%), 1b (5%), and 2b/c (3%). Phylogenetic analysis revealed 156 (78%) sequences that formed 11 clusters (bootstrap value > 70%) containing between 4 and 37 individual sequences. Country mixing was associated with larger cluster size (17 vs 4.5 sequences; P = .03). "Molecular clock" analysis indicated that the majority (85%) of transmissions occurred since 1996.

CONCLUSIONS

Phylogenetic analysis revealed a large international network of HCV transmission among HIV-positive MSM. The rapid spread of HCV among neighboring countries is supported by the large proportion (74%) of European MSM infected with an HCV strain co-circulating in multiple European countries, the low evolutionary distances among HCV isolates from different countries, and the trend toward increased country mixing with increasing cluster size. Temporally, this epidemic coincides with the introduction of highly active antiretroviral therapy and associated increases in sexual risk behaviors. International collaborative public health efforts are needed to mitigate HCV transmission among this population.

Potential impact of vaccination on the hepatitis C virus epidemic in injection drug users

BACKGROUND

Hepatitis C virus (HCV) causes significant morbidity and mortality in injecting drug users (IDU) worldwide. HCV vaccine candidates have shown promise for reducing the infectivity of acute infection and averting chronic infection, yet the impact of varying levels of vaccine efficacy and vaccine delivery strategies on the HCV epidemic in IDU have not been explored.

METHODS

We utilized extensive data on injecting behavior collected in the UFO Study of young IDU in San Francisco to construct a stochastic individual-based model that reflects heterogeneous injecting risk behavior, historical HCV trends, and existing information on viral dynamics and vaccine characteristics.

RESULTS

Our modeled HCV rate closely paralleled observed HCV incidence in San Francisco, with estimated incidence of 59% per person year (ppy) early in the epidemic, and 27% ppy after risk reduction was introduced. Chronic HCV infection, the clinically relevant state of HCV infection that leads to liver disease and hepatocellular cancer, was estimated at 22% ppy (± 3%) early in the epidemic and 14% ppy (± 2%) after risk reduction was introduced. We considered several scenarios, and highlight that a vaccine with 50% to 80% efficacy targeted to high-risk or sero-negative IDU at a high vaccination rate could further reduce chronic HCV incidence in IDU to 2-7% ppy 30 years after its introduction.

CONCLUSIONS

Our results underscore the importance of further efforts to develop both HCV vaccines and optimal systems of delivery to IDU populations.

FibroScan used in street-based outreach for drug users is useful for hepatitis C virus screening and management: a prospective study

Although hepatitis C virus (HCV) infection prevalence is high among drug users, they do not commonly receive regular care in academic centres. The aim of this prospective study was to assess the influence of FibroScan use on HCV screening and management in street-based outreach. From January 2006 to January 2007, all consecutive drug users were offered noninvasive evaluation of liver fibrosis with FibroScan. After FibroScan, parameters were recorded with a structured, face-to-face questionnaire by outreach workers. All 298 subjects accepted FibroScan evaluation drug use was--ever injected heroin (69%), ever snorted or injected cocaine (89%), current chronic alcohol abuse (44%). The median FibroScan score was 5.3 kPa. Before blood sampling, 34% of subjects reported HCV positivity. HCV positivity was found in 83 cases. All these subjects had positive HCV-RNA. Forty-five subjects agreed to meet a hepatologist. By multivariate analysis, never snorted cocaine, consumed alcohol < 21 drinks per week, duration of injected heroin > 7 years, and FibroScan > 7.1 kPa were significantly associated with HCV positivity. Thus in a street-based outreach service for drug users, the acceptance of FibroScan is excellent. FibroScan with a hospital-based physician may facilitate screening and management of drug users for HCV infection.

A meta-analysis of the hepatitis C virus distribution in diverse racial/ethnic drug injector groups

Hepatitis C virus (HCV) is mostly transmitted through blood-to-blood contact during injection drug use via shared contaminated syringes/needles or injection paraphernalia. This paper used meta-analytic methods to assess whether HCV prevalence and incidence varied across different racial/ethnic groups of injection drug users (IDUs) sampled internationally. The 29 prevalence and 11 incidence studies identified as part of the HCV Synthesis Project were categorized into subgroups based on similar racial/ethnic comparisons. The effect estimate used was the odds or risk ratio comparing HCV prevalence or incidence rates in racial/ethnic minority groups versus those of majority status. For prevalence studies, the clearest disparity in HCV status was observed in the Canadian and Australian Aboriginal versus White comparison, followed by the US non-White versus White categories. Overall, Hispanic IDUs had greater HCV prevalence, and HCV prevalence in African-Americans was not significantly greater than that of Whites in the US. Aboriginal groups showed higher HCV seroconversion rates when compared to others, and African-Americans had lower seroconversion rates compared to other IDUs in the US. The findings suggest that certain minority groups have elevated HCV rates in comparison to other IDUs, which may be a consequence of stigma, discrimination, different risk behaviors or decreased access to health care, services and preventive education. Future research should seek to explicitly explore and explain racial/ethnic variations in HCV prevalence and incidence, and define the groups more precisely to allow for more accurate detection of possible racial/ethnic differences in HCV rates.

Meta-regression of hepatitis C virus infection in relation to time since onset of illicit drug injection: the influence of time and place

The authors examined the relation between time since onset of illicit drug injection (time at risk) and rates of hepatitis C virus (HCV) infection by using meta-regression. In 72 prevalence studies, median time since onset of injection was 7.24 years and median prevalence was 66.02%. The model showed statistically significant linear and quadratic effects of time at risk on HCV prevalence and significantly higher prevalence in developing and transitional countries and in earlier samples (1985-1995). In developed countries post-1995, mean fitted prevalence was 32.02% (95% confidence interval: 25.31, 39.58) at 1 year of injection and 53.01% (95% confidence interval: 40.69, 65.09) at 5 years. In developing/transitional countries post-1995, mean fitted HCV prevalence was 59.13% (95% confidence interval: 30.39, 82.74) at 1 year of injection. In 10 incidence studies, median time at risk was 5.29 years and median cumulative HCV incidence was 20.69%. Mean fitted cumulative incidence was 27.63% (95% confidence interval: 16.92, 41.70) at 1 year of drug injection. The authors concluded that time to HCV infection in developed countries has lengthened. More rapid onset of HCV infection in drug injectors in developing/transitional countries resembles an earlier era of the HCV epidemic in other regions.

New challenges for mathematical and statistical modeling of HIV and hepatitis C virus in injecting drug users

Injecting drug users are not only driving blood-borne transmission of HIV and hepatitis C virus but also likely drive sexual transmission of HIV in large parts of the world. Mathematical and statistical modeling can provide important insights in these epidemiological processes and on the potential impact of interventions but have been little used to date. This review aims to discuss the potential areas of application of modeling in the field of viral infections in injecting drug users. After reviewing key examples of published modeling work on HIV and hepatitis C virus in injecting drug users, we discuss recent developments in the epidemiology, diagnosis, treatment and prevention of these infections. In particular, new methods for the diagnosis of early HIV infection, new antivirals for a more effective treatment of HIV, hepatitis B and hepatitis C virus infections, new concepts in design and surveillance of interventions for drug users and increasing possibilities of molecular typing of pathogens are changing the questions and decisions for public health policy makers who deal with drug-related infectious diseases. Research including mathematical modeling is needed to understand the impact of new diagnostic tools, new treatment options and combined intervention strategies on the epidemiology of viral infections in injecting drug users. Methodological advances in mathematical modeling are required to adequately approach some of the ensuing research questions. Modeling has much to offer for solving urgent policy questions, but current levels of funding in modeling research are insufficient and need to be scaled up to make better use of these possibilities.

Critical issues in the treatment of hepatitis C virus infection in methadone maintenance patients

AIMS

Hepatitis C virus (HCV) infection is a common chronic complication of injection drug use. Methadone maintenance programs contain large numbers of patients infected with HCV. This paper reviews HCV infection with emphasis on the medical care of HCV-infected, or HCV and human immunodeficiency virus co-infected, patients on methadone or buprenorphine maintenance.

METHODS

Literature searches using PubMed, PsycINFO and SocINDEX were used to identify papers from 1990-present on antiviral therapy for HCV in methadone maintenance patients and on liver transplantation in methadone maintenance patients.

RESULTS

Injection drug use is the most significant risk factor for HCV infection in most western countries. The prevalence of HCV antibody is high in injection drug users (53-96%) and in patients enrolled in methadone maintenance programs (67-96%). Studies of antiviral therapy for HCV in methadone maintenance patients show rates of sustained virological response (SVR), defined as negative HCV-RNA 24 weeks after the end of treatment, of 28-94%. In studies with contrast groups, no significant differences in SVR between methadone and contrast groups were found. Excellent completion rates of antiviral therapy (72-100%) were found in five of six studies. There are many barriers to methadone maintenance patients' receiving antiviral therapy, and research on overcoming barriers is discussed. Liver transplantation has been successful in methadone maintenance patients but has not been utilized widely.

CONCLUSION

High quality medical care for all aspects of HCV infection can be provided to methadone maintenance patients. The literature supports the effectiveness of such services, but the reality is that most patients do not receive them.

The changing epidemiology of hepatitis C virus infection in Europe

The epidemic of hepatitis C virus (HCV) infection in Europe is continuously evolving and epidemiological parameters (prevalence, incidence, disease transmission patterns and genotype distribution) have changed substantially during the last 15 years. Four main factors contribute to such changes: increased blood transfusion safety, improvement of healthcare conditions, continuous expansion of intravenous drug use and immigration to Europe from endemic areas. As a result, intravenous drug use has become the main risk factor for HCV transmission, prevalent infections have increased and genotype distribution has changed and diversified. Hence, prevalence data from studies conducted a decade ago may not be useful to estimate the current and future burden of HCV infection and additional epidemiological studies should be conducted, as well as new preventive strategies implemented to control the silent epidemic. This review summarizes recently published data on the epidemiology of HCV infection in Europe focusing on the factors currently shaping the epidemic.

Estimating past hepatitis C infection risk from reported risk factor histories: implications for imputing age of infection and modeling fibrosis progression

Background

Chronic hepatitis C virus infection is prevalent and often causes hepatic fibrosis, which can progress to cirrhosis and cause liver cancer or liver failure. Study of fibrosis progression often relies on imputing the time of infection, often as the reported age of first injection drug use. We sought to examine the accuracy of such imputation and implications for modeling factors that influence progression rates.

Methods

We analyzed cross-sectional data on hepatitis C antibody status and reported risk factor histories from two large studies, the Women's Interagency HIV Study and the Urban Health Study, using modern survival analysis methods for current status data to model past infection risk year by year. We compared fitted distributions of past infection risk to reported age of first injection drug use.

Results

Although injection drug use appeared to be a very strong risk factor, models for both studies showed that many subjects had considerable probability of having been infected substantially before or after their reported age of first injection drug use. Persons reporting younger age of first injection drug use were more likely to have been infected after, and persons reporting older age of first injection drug use were more likely to have been infected before.

Conclusion

In cross-sectional studies of fibrosis progression where date of HCV infection is estimated from risk factor histories, modern methods such as multiple imputation should be used to account for the substantial uncertainty about when infection occurred. The models presented here can provide the inputs needed by such methods. Using reported age of first injection drug use as the time of infection in studies of fibrosis progression is likely to produce a spuriously strong association of younger age of infection with slower rate of progression.

Major decline of hepatitis C virus incidence rate over two decades in a cohort of drug users

Injecting drug users (DU) are at high risk for hepatitis C virus (HCV) and HIV infections. To examine the prevalence and incidence of these infections over a 20-year period (1985-2005), the authors evaluated 1276 DU from the Amsterdam Cohort Studies who had been tested prospectively for HIV infection and retrospectively for HCV infection. To compare HCV and HIV incidences, a smooth trend was assumed for both curves over calendar time. Risk factors for HCV seroconversion were determined using Poisson regression. Among ever-injecting DU, the prevalence of HCV antibodies was 84.5% at study entry, and 30.9% were co-infected with HIV. Their yearly HCV incidence dropped from 27.5/100 person years (PY) in the 1980s to 2/100 PY in recent years. In multivariate analyses, ever-injecting DU who currently injected and borrowed needles were at increased risk of HCV seroconversion (incidence rate ratio 29.9, 95% CI 12.6, 70.9) compared to ever-injecting DU who did not currently inject. The risk of HCV seroconversion decreased over calendar time. The HCV incidence in ever-injecting DU was on average 4.4 times the HIV incidence, a pattern seen over the entire study period. The simultaneous decline of both HCV and HIV incidence probably results from reduced risk behavior at the population level.

Modelling the impact on Hepatitis C transmission of reducing syringe sharing: London case study

BACKGROUND

Hepatitis C virus (HCV) prevalence and incidence among injecting drug users (IDUs) has increased in London and rest of UK. To inform public health action, mathematical modelling is used to explore the possible impact of strategies to decrease syringe sharing.

METHODS

A mathematical model was developed to simulate HCV transmission amongst IDUs in London. Because of parameter uncertainty, numerical search algorithms were used to obtain different model fits to HCV seroprevalence data from London for 2002-03. These simulations were used to explore the likely impact of HCV prevention activities that reduce syringe sharing amongst all IDUs, IDUs that have injected for greater than one year, or IDUs with lower or higher frequencies of syringe sharing.

RESULTS

Key differences between model fits centred on how they simulated the high HCV incidence amongst new injectors, either through assuming increased HCV infectivity during acute infection, a large sub-group of high frequency syringe sharers, or increased sharing among new IDUs. Despite parameter uncertainty, the model projections suggest that modest reductions in syringe sharing frequency (<25%) will reduce the HCV seroprevalence in newly initiated IDUs (injecting less than four years) but much larger and sustained reductions (>50%) are required to reduce the HCV seroprevalence in long-term IDUs (injecting more than 8 years). Critically the model also suggested that large reductions in HCV seroprevalence will be achieved only if interventions target all IDUs and reach IDUs within 12 months of injecting.

DISCUSSION

Public health interventions must reduce syringe sharing amongst all IDUs, including newly initiated IDUs, and be sustained for many years to reduce HCV infection. More accurate data on key behavioural (sharing frequency) and biological (percentage of infected IDUs that clear infection) parameters is required to improve model projections.