Standardization of enzyme-linked immunosorbent assay ELISA to detect anti-Toxoplasma gondii IgM and IgG antibodies, and comparison with the indirect immunofluorescence technique

摘要

s Serology has been the most popular method to diagnose toxoplasmosis. Accordingly, this study standardizes an enzyme-linked immunosorbent assay (ELISA) and compares its results with the IFI technique. In the IgG detection test, the standardized technique presented a sensibility (S) of 96.77%, a specificity (SP) of 75%, with a positive predictive value (PPV) of 83.33%, a negative predictive value (NPV) of 94.74%, and an adjusted concordance (K) of 73.50%. The IFI exhibited 83.87% for S, 79.16% for SP, 83.81% for PPV, 79.16% for NPV, and 63% for K. The rough concordance between these two tests (ELISA/IFI) was 88.35% for the IgG detection test and 81.55% for the IgM detection test. K was 70.82% and 1.31% for IgG and IgM, respectively, the correlation index (r) being 0.556 for IgG and -0.023 for IgM. We can conclude that standardized ELISA-IgG is indicated in serologic selection processes, whereas the ELISA-IgM is not recommended for presenting low values for the adjusted concordance with the reference technique, which suggests not very reliable results.