Distribution of hepatitis C virus genotypes among injecting drug users in contact with treatment centers in Belgium, 2004-2005.

The aim of this study was to determine the current prevalence of HCV genotypes in injecting drug users recruited at treatment centers all over Belgium, and to analyze if the distribution of genotypes was correlated with demographic characteristics, at-risk behaviors, and co-infection with other viruses. Therefore 147 anti-HCV-positive serum samples were selected for subsequent HCV RNA detection and genotyping. HCV RNA could be detected in 98 (67%) of the 147 serum samples. Genotype 1 (38%) and 3 (49%) were the most common genotypes followed by genotype 4 (9%) and genotype 2 (2%). One mixed infection (1%) was detected. The subtype could be determined in 80 cases: genotype 3a was the most prevalent (49%), followed by genotype 1a (16%) and genotype 1b (15%). No significant difference was found between the distribution of genotypes and the location of treatment centers, at-risk behaviors and co-infection with other viruses. Nevertheless, a slight variation over time could be identified (P = 0.06): one in two genotype 3 drug users started with their injecting drug use in the last 10 years (33% in the period 1995-1999 and 21% in the period > or =2000) compared to only one in four genotype 1 drug users (20% in the period 1995-1999 and 9% in the period > or =2000).