Background: Maternal seroconversion for Toxoplasma gondii during pregnancy is said to have a good role for diagnosis of congenital infection. 

Objective: To determine whether maternal serum levels of antibodies against Toxoplasma gondii parasite are associated with definite fetal parasitic infection and consequent pathology or not.

Patients  and  methods: Maternal serum IgA levels against toxoplasma gondii were measured in 29 patients with strongly suspected congenital toxoplasmosis (maternal IgM seroconversion with fetal pathology) out of 200 patients with suspected pathology. Their pregnancies were complicated by hydrocephalus (Group I, n=17), hydropes fetalis and other congenital anomalies (Group II, n=6), and fetal loss (Group III, n=6). They were compared with 17 women with negative IgM and normal pregnancies as a control group (Group IV). All cases were examined by ultrasonography for obtaining amniotic fluid samples during pregnancy. After termination; if possible; fetal cord serum samples were drawn for measuring the same antibodies. Also, placental imprints, placental samples and umbilical cord samples  were prepared for microscopic detection of the parasite. Hydrocephalic cases with or without meningomyelocele were treated by neonatal shunt operations with or without repair.

Results: Cases presented by maternal IgM seroconversion against toxoplasma gondii during pregnancy with suspected pathology (hydrocephalus, other anomalies, and abortions) showed significantly higher maternal specific toxoplasma IgA levels than the control group (166.7±27.2, 165.7±21.1, and 149.7±9.1 respectively vs.    127.2±15.3, p<0.001). Microscopic parasitic detection was positive in 3/11 (27.3%) in the amniotic fluid and in 1/11 (9.1%) in placental imprints of these cases. Conventional  serological neonatal testing for specific toxoplasma IgA revealed sensitivity and specificity of 77.8% and 100% respectively. The combination of the results of conventional  serological neonatal testing for specific toxoplasma IgA with the results of parasitic detection (amniotic fluid and placenta) resulted in sensitivity and specificity of 94.4 and 100 respectively.

Conclusions: Detection of specific toxoplasma gondii IgA antibody response by ELISA is more reliable than IgM level for diagnosis of congenital toxoplasmosis.

Key  words: Congenital toxoplasmosis, specific IgA, seroconversion.