Prevalence and Clinical Implications of Occult Hepatitis B Viral Infection in Hemophilia Patients in Japan

The prevalence and clinical implications of occult hepatitis B virus (HBV) infection were investigated in the Japanese patients with hemophilia in whom a high prevalence of infection with transfusion-transmissible viruses has been reported. HBV DNA was detected in the sera of 22 of 43 (51.2%) patients with hemophilia who were negative for HBV surface antigen (HBs), indicating that these patients had occult HBV infection. No factor, including age, type or severity of hemophilia, presence of HBs or HBV core (HBc) antibody, or coinfection with hepatitis C virus (HCV) or human immunodeficiency virus (HIV) was associated with occult HBV infection, except for high anti-HBc titer and/or coinfection with HCV genotype 1 (1a or 1b). In general, occult HBV infection did not appear to have significant clinical implications. However, in patients in whom HBV was detected by PCR specific for the surface (S)-region, higher alanine aminotransferase levels were observed. The genotype of the occult HBV in the present study was exclusively the domestic type indigenous to Japan (genotype C), suggesting a different route of transmission for HBV in comparison to HCV and HIV in this population.