Inapparent Infections in the Course of an Epidemic of Australia-SH-Antigen Positive Hepatitis

Two forms of infectious jaundice are recognized, serum hepatitis (with a long incubation period), in which Australia-SH antigen can be demonstrated in the patient's serum1,2; and infectious hepatitis (with a short incubation period), in which Australia-SH antigen cannot be demonstrated. Previously studied local outbreaks of infectious hepatitis were all Australia-SH-antigen negative2-7 (our observations in three epidemics). It has not been possible in these to assess whether in addition to the apparent forms there have also been inapparent ones without jaundice or elevated serum transaminase levels.Between March 20 and April 30, 1970, 18 pulmonary disease patients in a hospital developed acute hepatitis as shown by high values of transaminases, jaundice, and subjective symptoms. Eleven of these patients (61%) were found positive for Australia-SH antigen tested by immunodiffusion and complement fixation assay (Figure). Since the examination for Australia-SH antigen was not performed until the middle of May 1970, the