A reverse transcriptase-polymerase chain reaction procedure (RT-PCR) for the detection of hepatitis G virus (HGV) RNA was used to examine the prevalence of HGV infection and HGV-related disease in Japan. Among 48 patients with acute non-A, B, C, D, E (non-A-E) hepatitis (five transfusion-associated cases and 43 sporadic cases), only one patient (2%), a transfusion recipient, was HGV RNA positive. Similarly, among 50 patients with established chronic non-A-E hepatitis, only two (4%) were positive for HGV RNA. These frequencies were not significantly different from those in 129 voluntary blood donors (0.8%). By contrast, HGV infection was relatively common among patients who were also infected with other hepatitis viruses. HGV co-infection or superinfection was found in seven of 53 (13%) patients with acute hepatitis C, in 15 of 126 (12%) patients with chronic hepatitis C, in three of 21 (14%) patients with acute hepatitis B and in four of 81 (5%) patients with chronic hepatitis B. Among the 29 dually infected patients, 15 (52%) had a history of blood transfusion. HGV was also detected in seven (10%) of 69 haemodialysis patients, of whom only one had a dual infection with hepatitis C virus (HCV) and an elevated aminotransferase level.
In conclusion: HGV RNA was found in only a low percentage of patients with either acute or chronic non-A-E hepatitis: HGV appears to co-infect or superinfect in 10-15% of HCV infections and in 5-15% of HBV infections; the prevalence of HGV infection (0.8%) among voluntary blood donors in Japan is similar to that for HCV infection; a history of blood transfusion was obtained in 22 (55%) of the total 40 HGV-positive subjects; and isolated HGV infection appears to have a low disease burden.