Background and Aim from January 2005 to September 2007 we analyzed the newborns of mothers with documented seroconversion during pregnancy, to demonstrate the importance of the Western Blot test for an early diagnosis of Congenital Toxoplasmosis and to avoid unnecessary treatment in asymptomatic infants.

Materials and Methods each infant underwent a prospective serological and clinical follow-up consisting of dosing IgG, IgM and IgA antibodies at the first week of life and then at the 1st, 2nd, 3rd, 6th, 9th and 12th month by conventional immunoenzymatic assays (ELISA; ELFA). Only newborns considered at high risk of congenital infection (late maternal seroconversion, doubtful IgM/IgA by conventional tests, uncertain maternal seroconversion, IgG titres persisting or increasing) performed the WB test, always within the first three months of life.

Results During the study period we screened 89 babies for Congenital Toxoplasmosis and we carried out the WB test on 11 mother-baby serum pairs (12.36%). In 9/11 cases (82%) the WB test confirmed the maternal origin of IgG antibodies thus excluding congenital infection; in 2/11 cases (18%) we diagnosed congenital Toxoplasmosis. Only one of the two infected children had a positive IgM ELFA result, while the other had a negative IgM ELFA result.

Conclusions The WB method enabled us to exclude the diagnosis of Congenital Toxoplasmosis in 9 of 11 children, thus avoiding therapy with significant side effects; we correctly identified 2 infected infants that promptly began treatment. None of the 2 infected children had cerebral anomalies; one of them showed chorioretinitis.