Chronic hepatitis C in Sweden: Genotype distribution over time in different epidemiological settings

Hepatitis C virus (HCV) strains are divided into 6 genotypes and several su btypes, Recent studies reported a change in the relative frequency of genot ypes within certain regions. We studied the HCV genotype in 312 Swedish pat ients with chronic hepatitis C, using a core region primer-specific PCR, an d grouped the patients according to parenteral risk factors. The date of in fection could be estimated in 127 cases. Genotypes 1a (35%) and 3 (31%) wer e the most common genotypes, followed by genotype 2 (17%), while only 6% ha d genotype Ib, Genotype 3 was relatively more frequent among subjects infec ted sexually or by intravenous drug use. The genotype distribution was diff erent from that in studies from other parts of the world, with a lower freq uency of genotype 1 (especially 1b) and a higher frequency of genotype 3, T he frequency of genotype 1b has decreased and genotype 3 increased over tim e. The reasons for a different distribution of genotypes in Sweden, compare d with other countries, might be a relatively recent introduction of HCV in to the population, or a different pattern of transmission.