Hepatitis C virus infection in Japan.

Because of the high incidence of non-A non-B post transfusion hepatitis and its relation to hepatocellular carcinoma, HCV antibody screening for blood transfusion was begun in November 1989. Seroepidemiological studies revealed the great magnitude of HCV infection in acute hepatitis, chronic hepatitis, liver cirrhosis and hepatocellular carcinoma in Japan. Approximately 1.6 million HCV antibody-positive persons are now in Japan. Major routes of infection are considered to be horizontal blood borne infection in the past and blood transfusion.