F2 and hepatitis A virus infection: Moreover, the definitions of subtypes of fulminant hepatitis were clarified; hepatitis patients with no or grade I encephalopathy, but showing prothrombin time values of ≤40 % of the standardized value were diagnosed as having “severe type of acute hepatitis”, while those with grade II or more severe hepatic encephalopathy developing between 8 and 24 weeks after the disease symptoms onset, with prothrombin time values of ≤40 % of the standardized value were diagnosed as having LOHF.