Age-sex distribution of Toxoplasma antibody in the South Australian population.

Sera from 1071 patients in nine age categories were screened for Toxoplasma antibody by indirect immunofluorescence. Thirty per cent of the sera contained antibody at a titre greater than or equal to 1/16. The percentage of sera containing antibody rose from 3% in the 6 months--5 years age group to a maximum of about 40% in the 31--40 years age group. It remained constant thereafter. Eleven per cent of the 84 sera with Toxoplasma antibody titres greater than or equal to 1/128 had Toxoplasma IgM titres greater than or equal to 1/32. No significant difference was found in the possession of antibody between the sexes.