Comparison of Serological Methods for the Diagnosis of Toxoplasmosis in Pregnant Women

Comparative evaluations of different serological methods for the diagnosis of toxoplasmosis in pregnant women remain limited, and the performance of indirect immunofluorescence assay (IFA), modified agglutination test (MAT), and chemiluminescent microparticle immunoassay (CMIA) has not been previously assessed simultaneously in this population. This study aimed to compare the performance of these three serological methods for the detection of Toxoplasma gondii antibodies in pregnant women. A total of 469 serum samples were collected from pregnant women receiving prenatal care through the Brazilian public healthcare system. Samples were tested using IFA, MAT, and CMIA for the detection of IgG and IgM antibodies. Statistical analyses included McNemar’s χ2 test, Kappa agreement, and Pearson and Spearman correlation coefficients. IFA and MAT showed higher IgG seropositivity rates (53.1% and 51.2%, respectively) compared to CMIA (46.7% and 48.6%). Agreement between CMIA and IFA was moderate for IgG (Kappa = 0.51) and very strong for IgM (Kappa = 0.89). Pearson’s correlation for IgG between CMIA and IFA was moderate (r = 0.678), while Spearman’s correlation for IgM was weak. IFA and MAT demonstrated greater sensitivity for IgG detection than CMIA, while CMIA and IFA performed similarly for IgM. Conventional methods may complement automated systems to improve diagnostic accuracy in prenatal screening.