Hepatitis C virus (HCV) infection is widespread among injection drug users. Young women seem to be at higher risk of acquiring HCV. To optimize future intervention and prevention measures, we studied the epidemiology of human immunodeficiency virus (HIV), hepatitis B (HBV), and HCV infection among men and women. Inclusion criteria for this cross-sectional multicentre study were: history of ever injecting drugs, age > 18 y, and no previous HIV diagnosis. In 310 participants, plasma/serum samples were analysed for HBV, HIV and HCV (anti-HCV, HCV-RNA, and HCV genotype). HCV antibodies were noted in 268 (86.5%) participants, of whom 207 (77.0%) also had detectable HCV-RNA. Genotypes 1 and 3 dominated, at 35.9% and 33.0%, respectively. Women acquired HCV (but not HBV) to a significantly higher degree (RR 2.97, 95% confidence interval 1.11-7.93) during the first y of injecting drugs. They also recovered spontaneously from HCV infection more frequently (RR 2.49, 95% CI 1.28-4.53). The HCV prevalence of about 50% within 2 y after initiation of injection drug use underlines the need for early intervention efforts. Possible causes for higher HCV prevalence and the implications of favourable spontaneous recovery rates among women should be considered when designing intervention and prevention measures.

This was a multicentre study with risk perception as the theoretical framework, investigating if risk behaviours change when injecting drug users (IDUs) are aware of their hepatitis C virus (HCV) status and had assessed the health consequences with HCV infection. Two hundred and thirteen participants aged 15-40 y were analysed. Sharing of needles and of other injecting equipment were common both among participants who reported HCV-positive status (74%, 95% confidence interval (CI) 65.3-80.1%) and among those who reported HCV status unknown (68%, 95% CI 56.0-78.4%). Participants associating very severe health consequences with HCV infection and those who did not know of any health consequences with HCV infection shared needles at almost the same rate (78%, 95% CI 62.5-87.7 vs 69%, 95% CI 8.0-78.9, respectively). Sharing of other injecting equipment was most common among participants with verified HCV-positive status (adjusted risk ratio 5.64, 95% CI 2.64-12.07). Knowledge of HCV status and assessment of health consequences with HCV infection were not enough to change injecting risk behaviours. Sharing of other injecting equipment was a more important risk factor than sharing needles for participants with verified HCV-positive status. It is suggested that professionals engage IDUs in risk analysis and open a dialogue about assessment in order to identify, quantify and characterize risks.

Monitoring injecting drug users' (IDUs) health is challenging because IDUs form a difficult to reach population. We examined the impact of recruitment setting on hepatitis C prevalence. Individual datasets from 12 studies were merged. Predictors of HCV positivity were sought through a multilevel analysis using a mixed-effects logistic model, with study identifier as random intercept. HCV prevalence ranged from 21% to 86% across the studies. Overall, HCV prevalence was higher in IDUs recruited in drug treatment centres compared to those recruited in low-threshold settings (74% and 42%, respectively, P < 0·001). Recruitment setting remained significantly associated with HCV prevalence after adjustment for duration of injecting and recent injection (adjusted odds ratio 0·7, 95% confidence interval 0·6-0·8, P = 0·05). Recruitment setting may have an impact on HCV prevalence estimates of IDUs in Europe. Assessing the impact of mixed recruitment strategies, including respondent-driven sampling, on HCV prevalence estimates, would be valuable.

Needle sharing is a risk factor for contracting blood-borne infections among injecting drug users (IDUs). We explored the relation of socio-financial, physical and mental health factors (ASI) to risk behaviour (Qr23) for contracting blood-borne infections among IDUs (Addiction Severity Index and Questionnaire for risk behaviour). 42 HIV negative IDUs were studied prospectively. The median age was 42.5 (range 18-61) y, 28 of 42 (67%) were males and median duration of injecting was 19.0 (range 0-43) y. HCV and HBV antibodies were found in 37 (88%) and 31 (71%) participants, respectively. Poly drug use was reported by 23 (55%) participants; amphetamine by 10 (24%) and heroin by 9 (21%). From the ASI data we were unable to find any statistically significant factor that was associated with needle sharing (n = 26/42, 61%) or sharing drug mixture/filter (n = 25/42, 59%). 19 (73%) of 26 participants who shared needles also shared drug mixture/filter. Of these 26 IDUs, 7 shared needles with partners, 11 with acquaintances, 3 with strangers and 5 with all categories. In conclusion, the study group showed differentiated risk behaviours for blood-borne infections with regard to various persons and to whom they were exposed. This suggests that IDUs may benefit from individualized counselling regarding risks for infections with HIV, HCV and HBV.

This study assessed risk behavior and preventive measures for hepatitis C among injecting drug users in Rotterdam, the Netherlands (452 participants, 2002-2003) and Stockholm, Sweden (310 participants, 2004-2006), two cities with contrasting drug policies. Uni- and multivariate logistic regression models were used. We found that the prevalence of hepatitis C was almost two times higher in participants from Stockholm than in participants from Rotterdam, even after adjustment for sex sharing paraphernalia (adjusted relative risk: 1.92, 95% confidence interval: 1.60-2.29). Follow-up comparative studies are needed to determine if policies with structured health programs can decrease transmission of hepatitis C.

The annual number of reported cases of human immunodeficiency virus (HIV) infection among injecting drug users (IDUs) in Sweden has been about 20 for more than 5 y, but in 2001 36 new cases were reported. Risk behaviour for contracting HIV infection was studied in 21 of 24 identified and evaluable IDUs with diagnosed HIV infection in the metropolitan area of Stockholm in 2001 and in 23 of 30 evaluable consecutive controls. HIV status was associated with general needle sharing (p = 0.04) and needle sharing with an HIV-positive individual (p = 0.0001), despite extensive information on possible transmission routes for HIV. These results indicate that efforts for reducing transmission of HIV should focus on HIV-negative and HIV-positive individuals with risk behaviour.