Abstract / Summary
Abstract Background In eastern Europe and central Asia, HIV incidence among people who inject drugs has continued to rise, yet contemporary bio-behavioural data from Bulgaria are scarce. We measured the prevalence of reactive screening markers for HIV, hepatitis B, hepatitis C and syphilis among people who use drugs in Sofia and examined their correlates. Methods Cross-sectional survey of 480 adults reporting illicit drug use in the previous month, recruited through mobile outreach in June–August 2024. Capillary blood was screened on site with rapid tests. Because the outcomes are common, associations are expressed as adjusted prevalence ratios from modified Poisson regression with robust variance, with covariates chosen from a directed acyclic graph rather than by significance screening. Results Of 480 participants (78.8% men, median age 40 years), 320 (66.7%, 95% confidence interval 62.3–70.9) had at least one reactive marker. Anti-HCV was reactive in 305 (63.5%, 59.1–67.9), anti-HIV in 61 (12.7%, 9.9–16.0), treponemal antibody in 15 (3.1%, 1.8–5.1) and HBsAg in 11 (2.3%, 1.1–4.1). Reactivity was concentrated among the 304 participants who had ever injected (anti-HCV 89.1% vs 19.3% among those who had not; anti-HIV 17.1% vs 5.1%), whereas treponemal antibody and HBsAg did not differ by injecting history. Anti-HCV reactivity rose from 25.0% at 20–29 years to 82.0% at 40–49 years (test for trend p < 0.001); anti-HIV showed no age trend (p = 0.37). Ever injecting was the strongest correlate of both anti-HCV (adjusted prevalence ratio 4.13, 2.99–5.70) and anti-HIV reactivity (4.29, 2.01–9.16). Current unstable housing was associated with anti-HIV reactivity (1.88, 1.14–3.11) but not with anti-HCV. Of 61 participants with reactive HIV tests, 53 (87%) were anti-HCV reactive. Conclusions Two thirds of people who use drugs reached by outreach in Sofia carry a reactive marker of blood-borne infection, and anti-HCV reactivity is close to universal among people with long injecting histories. The age pattern points to exposure accumulated over decades rather than a recently introduced epidemic. Because antibody testing cannot separate current from cleared hepatitis C, RNA testing is needed before treatment need can be estimated, and HIV and hepatitis services for this population should be integrated.