Duration of specific immunoglobulin A antibody following acute toxoplasmosis as determined by enzyme immunoassay and immunosorbent agglutination assay.

Modifications of an enzyme immunoassay (EIA) and an immunosorbent agglutination assay (ISAGA) for measuringToxoplasma gondii-specific IgM antibody were made to enable the measurement ofToxoplasma gondii-specific IgA antibody. It was shown that specific IgA could be measured by both assays but that the ISAGA was slightly more sensitive. IgA appears about two weeks after IgM and persists for 6 to 7 months. However, the IgA response varies considerably both in degree and duration, and demonstration of IgM antibody is at present the most suitable routine test for the diagnosis of recentToxoplasma gondii infection.