[Significance of Australia antigen in the differential diagnosis and prognosis of hepatitis].

The Australia-antigen (HBSAG) is a simple detectable marker of an infection with hepatitis B virus. By demonstration of HBSAG an acute hepatitis B can be differentiated from other forms. Likewise the detection of HBSAG in chronic active hepatitis can differentiate the viral induced type from the autoimmune type. HBSAG is important with respect to the prognosis of an acute hepatitis B, because persistence for some months points at a transition to chronic hepatitis.