Usefulness of Western blot in serological follow-up of newborns suspected of congenital toxoplasmosis.

The goal of the study reported here was to compare the results of Western blot with other serological methods for testing newborns suspected of having congenital toxoplasmosis. Western blot, enzyme-linked immunosorbent assay, immunoglobulin (Ig)M immunosorbent agglutination assay, and indirect immunofluorescence assay were performed on the sera of 126 neonates collected at birth and at 1 and 3 months of life. Western blot was more sensitive than IgM detection with the immunosorbent agglutination assay (82.6% vs. 69.6%), and the specificity of the two methods was 96.1% and 92.2%, respectively. Among the serological techniques tested, the combination of Western blot (IgG and IgM) with IgM immunosorbent agglutination assay achieved the greatest improvement in the sensitivity of early (postpartum) diagnosis of congenital toxoplasmosis.