Evaluation of IgG anti-toxoplasma avidity and polymerase chain reaction in the postnatal diagnosis of congenital toxoplasmosis.

Confirmatory tests for congenital toxoplasmosis were evaluated in 23 infected and 31 uninfected newborns. Conventional polymerase chain reaction was better than real-time polymerase chain reaction, but did not identify additional cases. Avidity tests added 2 new cases that were not identified by other criteria. Overall sensitivity was 82.6%. Avidity assay, but not polymerase chain reaction, increased the sensitivity of confirmatory assays in congenital toxoplasmosis.