Injecting drug use is often associated with deep-seated infection. In Lothian in Scotland there has been a recent increase in the use of injected new psychoactive substances (NPS). Patients who have injected NPS have presented with Staphylococcus aureus bacteraemia (SAB) with life-threatening complications. We describe a unique case-series of 14 episodes of SAB in ten patients. Users of injected NPS had a significantly higher incidence of endocarditis and cavitating pulmonary lesions (P < 0·05) compared to those who inject only opiates. Cases of SAB in people who inject NPS have contributed to a significant rise in the overall incidence of SAB in people who inject drugs (P < 0·05) which has in turn impacted on the ability of Lothian to meet national targets for reducing the incidence of SAB.

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.

A prospective cohort study estimated the incidence of hepatitis C virus (HCV) in drug injectors in South Wales (UK). In total, 286/481 eligible seronegative individuals were followed up after approximately 12 months. Dried blood spot samples were collected and tested for anti-HCV antibody and behavioural data were collected at baseline and follow-up. HCV incidence was 5·9/100 person-years [95% confidence interval (CI) 3·4–9·5]. HCV incidence was predicted by community size [incident rate ratio (IRR) 6·6, 95% CI 2·11–20·51, P=0·001], homelessness (IRR 2·9, 95% CI 1·02–8·28, P=0·047) and sharing injecting equipment (IRR 12·7, 95% CI 1·62–99·6, P=0·015). HCV incidence was reduced in individuals in opiate substitution treatment (IRR 0·34, 95% CI 0·12–0·99, P=0·047). In order to reduce follow-up bias we used multiple imputation of missing data using switching regression; after imputation estimated HCV incidence was 8·5/100 person-years (95% CI 5·4–12·7). HCV incidence varies with community size, equipment sharing and homelessness are associated with increased HCV incidence and opiate substitution treatment may be protective against HCV.

In the last decade, a declining prevalence of HCV infection has been described in injecting drug users (IDUs) in different countries. This study is the first to assess temporal trends in drug-injecting patterns, HCV infection rates and viral genotype distribution in 770 Brazilian IDUs, recruited by two cross-sectional studies (1994–1997 and 1999–2001). A substantial decline in the prevalence of HCV infection was found over the years (75% in 1994 vs. 20·6% in 2001, P<0·001) that may be a consequence of the significant reduction in the overall frequencies of drug injection and needle-sharing, as well as the participation of IDUs in initiatives aimed at reducing drug-related harm. No trend was found in terms of viral genotype distribution. Despite the favourable scenario, preventive measures must be maintained, especially in vulnerable subgroups such as young or new injectors, where risky behaviours through direct and indirect sharing practices remain common.