Contrasting patterns of hepatitis C virus infection in two regions from Tunisia.

This report is a population-based study describing the pattern of hepatitis C virus (HCV) infection in two distinct regions in Tunisia. The study included a total of 11,507 individuals sampled in 1996 from both genders, all age groups, urban and rural settings belonging to 2,973 families. HCV infection was assessed by commercial enzyme immunoassay (EIA) and immunoblot assays and detection of HCV RNA by PCR. HCV genotypes and subtypes were determined by sequencing in the 5'-untranslated region (UTR) viral genomic region and the INNO-LiPA HCVII genotyping kit. Genetic relatedness between HCV strains was assessed by sequencing of a portion of the NS5B region. HCV prevalence was significantly higher in the North-Western region than in the Southern one: 1.7% versus 0.2% (P < 10(-3), chi(2) = 8,506). There was no difference in positivity according to gender or living in rural or urban settings; the only significant risk factor was advanced age. HCV prevalence among household contacts of HCV positives was not significantly higher than the prevalence in the whole study population. These results indicate a heterogeneity in the geographical distribution of HCV in Tunisia. An increased HCV transmission occurs in the North-Western region with large predominance of genotype 1b (88%) and low contribution of intrafamilial transmission.