Genotyping of hepatitis C virus isolates from Basque Country, Spain.

The genotype of HCV was determined in 161 chronic HCV-infected patients. The patients were classified into three groups on the basis of the origin of the HCV infection: 50 patients had a history of intravenous drug use (IVDU) but no HIV infection; 41 patients had received blood transfusions, and 70 patients had no known exposure. The distribution of HCV genotypes was associated with the origin of infection and age of patients: genotype 1b was predominant among patients who had received blood transfusions and those without evidence of parenteral exposure (84.6% and 67.7%, respectively), whereas genotype 3a was present in 65.3% of IVDUs. Patients with genotype 1b were older than those with genotypes 1a or 3a: 50.3 +/- 12 vs. 34.1 +/- 9.9 and 31 +/- 5.4 years, respectively. These findings suggest that the pattern of HCV genotypes in our region is changing and that genotype 1b may be substituted by 3a as the dominant genotype in the future.