Continued transmission of hepatitis B and C viruses, but no transmission of human immunodeficiency virus among intravenous drug users participating in a syringe/needle exchange program

The virological efficacy of a syringe/needle exchange program was evaluated in a cohort incidence study. Of 698 intravenous drug users (IVDUs) initial ly recruited, 15 (2.1%) were HIV-positive at baseline. Adequate follow-up w as possible in 515 (74%) and showed no new cases of HIV infection during a median of 31 months, Most IVDUs had been previously exposed to HBV (anti-HB c-positive 70.1%) and HCV (anti-HCV-positive 90.7%). Of those 159 IVDUs neg ative at baseline for anti-HBc and/or anti-HCV, 56 (35%) seroconverted to o ne or both viruses during follow-up, corresponding to 11.7 seroconversions/ 100 y at risk for HBV and 26.3 seroconversions/100 y for HCV. Multiple logi stic regression analysis showed hepatitis seroconversion to correlate with imprisonment during the study (OR 2.2; 95% CI 1.01-4.74), absence of drug-f ree periods (OR 5.7; CI 1.44-22.3) and frequent syringe/needle exchanges (O R 1.31; CI 1.02-1.7). The absence of HIV spread was probably partly due to the low prevalence of HIV-infected IVDUs in the city. Despite free syringes and needles, both HBV and HCV continued to spread at high rates. Neverthel ess, syringe/needle exchange programs, coupled with monitoring of serostatu s provide good surveillance and are valuable for further assessment of rema ining risks.