Molecular epidemiology of hepatitis C among drug users in Flanders, Belgium: association of genotype with clinical parameters and with sex- and drug-related risk behaviours.

The aim of this study was to determine the genotypic variation of hepatitis C among drug users in Flanders and to relate the distribution of genotypes to the characteristics of the population. Hepatitis C virus RNA (HCV-RNA) quantification and genotyping was performed on stored samples from 161 anti-HCV-positive injecting and non-injecting drug users. Information on sociodemographic status, drug-related risk behaviour and sexual risk behaviour was available for each drug user. HCV-RNA was present in 152 of 161 samples (94.4%). Genotype 1 was predominant (48.7%), followed by genotype 3 (41.2%), genotype 4 (8.8%) and genotype 2 (1.4%). In the multivariate analysis, lack of a history of injecting drug use was confirmed as a statistically significant predictor for infection with genotype 1. Predictors for infection with genotype 3 were the presence of anti-HBc antibodies and a history of injecting drug use. Being tattooed emerged as a statistically significant predictor for infection with genotype 4. The 94.4% prevalence of HCV-RNA among anti-HCV-positive drug users was considerably higher than the 54-86% chronicity rate found globally among HCV-infected patients. The results of this study suggest the existence of separate transmission networks for injecting drug users and non-injecting drug users. Finally, the results suggest that tattooing practices play a role in the spread of HCV among drug users.