and GBV-C. The mutation rate of the GBV-C genome has been estimated at 10−2 to 10−3 substitutions/site/year. Epidemiology GBV-C infection has been found worldwide and currently infects around a sixth of the world's population. High prevalence is observed among subjects with the risk of parenteral exposures, including those with exposure to blood and blood products, those on hemodialysis, and intravenous drug users. Sexual contact and vertical transmission may occur. About 10–25% of hepatitis C-infected patients and 14–36% of drug users who are seropositive for HIV-1 show the evidence of GBV-C infection. It has been classified into seven genotypes and many subtypes with distinct geographical distributions. Genotypes 1 and 2 are prevalent in Northern and Central Africa and in Americas. Genotypes 3 and 4 are commons in Asia. Genotype 5 is present in Central and Southern Africa. Genotype 6 can be encountered in Southeast Asia. Finally, genotype 7 has been reported in China. Infection with multiple genotypes is possible. Genotype 5 appears to be basal in the phylogenetic tree, suggesting an African origin for this virus. History Hepatitis G virus and GB virus C (GBV-C) are RNA viruses that were independently identified in 1995, and were subsequently found to be two isolates of the same virus. Although GBV-C was initially thought to be associated with chronic hepatitis, extensive investigation failed to identify any association between this virus and any clinical illness. GB Virus C (and indeed, GBV-A and GBV-B) is named after the surgeon, G. Barker, who fell ill in 1966 with a non-A non-B hepatitis which at the time was thought to have been caused by a new, infectious hepatic virus. References External links Pegiviruses HIV/AIDS