Serological studies of Australia-antigenaemia in different categories of sick and healthy persons.

Sera (1,333) were collected from patients at various days after the onset of manifest B-virus hepatitis; from long term asymptomatic carriers of Au-antigen, with or without a demonstrable history of hepatitis; and from apparently healthy Au-negative persons. Au-anti-genaemia was tested with gel-diffusion (GD), counter immunoelectrophoresis (CIE), reversed haemagglutination (RHA) and complement fixation (CF). The CF test was found to be as sensitive as the RHA test, about 10 times more sensitive than the CIE, and about 25 times more sensitive than the GD test. With greater amounts of antibodies used in CF tests, the titres of AU-antigen were higher and the heights of prozones were lower. It is stressed that in screening for Au-antigen, sera should be tested in dilutions from 2 to 64, against 4 to 8 CF units of antibody. The frequency of asymptomatic long term Au-carriers, in the group with a known history of hepatitis, amounted to 41%, and themean titre of Au-antigen was 1:392. In the group of long-term carriers with no detectable history of hepatitis, the rate of Au-carriers was 1.6%, and the mean titre was 1:19.