Prevalence and determinants of anti-HCV seropositivity and of HCV genotype among intravenous drug users in Berlin.

A cross-sectional study was carried out to identify risk factors for seropositivity for antibodies against hepatitis C virus (HCV) and to assess to the distribution and determinants of HCV genotypes among intravenous drug users (IVDUs). The study population consisted of 405 IVDUs. Serum specimens were tested for seromarkers for HCV, for human immunodeficiency virus (HIV), for hepatitis B virus (HBV) and for syphilis. HCV RNA determination by polymerase chain reaction (PCR) and virus typing were performed in a subsample of anti-HCV-positive specimens (n=135). Of the IVDUs, 83% were anti-HCV-positive, 18% HIV-infected, and 58% HBV (anti-HBc)-positive. Longer duration of intravenous drug use, syringe sharing in prison, and higher number of IDVU sex partners were independent risk factors for anti-HCV positivity. GCV RNA was detected in 76% of anti-HCV-positive IVDUs. HCV genotypes 1 (49%) and 3 (44%) were most commonly found. All the type 3 isolates were identified as subtype 3a, and 95% of the type 1 isolates as subtype 1b. In logistic regression analysis, HCV type 3a viraemia was significantly associated with lack of HIV infection and a higher number of sex partners. The results indicate that preventive measures are needed to reduce syringe sharing among IVDUs in prisons. Sexual contacts with other IVDUs may play a role in the HCV epidemic among IVDUs. In Germany, HCV type 3a infection appears to be much more common among IVDUs than among other HCV risk groups such as transfusion recipients or haemophiliacs.