Toxoplasma gondii: detection of antibodies in human saliva and serum

Saliva samples from 27 patients with a recent toxoplasma infection were tested for specific IgG, IgM and IgA antibodies to Toxoplasma gondii. Thirteen of the 27 saliva samples were positive for IgG anti-T. gondii by direct agglutination and 8 of the 27 were positive for IgM anti-T. gondii by an immunosorbent agglutination assay. Twenty of the 27 saliva samples were positive for IgG antibody on toxoplasma immunoblots with three major immunodominant antigens; 38, 30 and 35 kDa. IgA results on toxoplasma immunoblots were positive for all three groups tested, recently infected patients, chronically infected and seronegative adults without distinguishing between them. The 35 and 43 kDa antigens were the most frequently detected proteins. IgM in saliva gave negative or very weak reactions. None of the eight seronegative or the 17 chronically infected adults gave positive results in any of the tests performed to detect IgG or IgM in saliva. Serial saliva and serum samples from a laboratory-infected patient were collected and tested for toxoplasma-specific IgG, IgM and IgA. IgG in saliva was detected by 27 days post infection (p.i.) and was negative by 81 days p.i.; it detected mainly the 38 and 30 kDa antigens. IgM in saliva was detected by 11 days p.i. and was negative by 81 days p.i., with no reaction on immunoblots.