Hepatitis-associated antigen in sporadic cases of acute viral hepatitis.

Serum specimens collected during the period from September 1970 to April 1971 from hospitalized patients and apparently healthy staff members at risk were tested for the presence of hepatitis-associated antigen (HAA) by the parallel use of three techniques: the complement fixation test, crossover-electrophoresis and immuno-electronmicroscopy.Out of a total of 204 persons investigated 63 (30.9%) were found to harbour the antigen. The HAA-positive sera originated almost exclusively from sporadic cases of acute viral hepatitis (clinically diagnosed as "infectious hepatitis" or "serum hepatitis"). The great majority of the hepatitis cases studied had a history of drug addiction.