[Ways for the evaluation of the infectivity of HBS-Ag positive subjects].

It is highly desirable for the subject with HBsAg-positive blood and his contacts to be aware of the attendant infectivity. It appears that only blood containing DANE particles is infective. Today it is known that the blood of patients with chronic active hepatitis, of HBsAg-positive patients under immunosuppression, and during the early phase of acute viral hepatitis, contains large amounts of DANA particles. Therefore, from clinical data and histological evaluation of the liver it is possible to deduce the level of infectivity risk in a given patient. It is still an open question whether DNA-polymerase, HBc-antigen or the E-antigen provide helpful information on the infectivity of HBsAg blood.