Enzyme-linked immunosorbent assay for IgA antibodies to Trypanosoma cruzi in congenital infection

With the aim of achieving earlier diagnosis of congenital Trypanosoma cruzi infection, we assessed the usefulness of detecting specific IgA antibody b y an ELISA. We evaluated 12 pregnant women chronically infected with T. cru zi, their newborn infants, and three additional neonates with parasitemia a t birth. The IgA-specific antibody was detected by adapting the procedure f or use of a commercial IgG ELISA, the Hemagen(R) Chagas' Kit (Hemagen Diagn ostics, Inc., Waltham, MA). Trypanosoma cruzi-specific IgA was detected in 10 (83%) of 12 mothers at delivery, in one of three parasitemic infants, an d one of 12 newborns of the chronically infected women. Testing of 13 infan ts at six months of age revealed IgA in seven infants (54%),of whom four al so had persistent T. cruzi-specific IgG. Detection of T. cruzi-specific IgA could provide a criterion for diagnosis of congenital infection in the abs ence of detectable parasitemia.