IMPORTANCE OF AVIDITY IGG TEST IN CONGENITAL TOXOPLASMOSIS

Abstract

The purpose of this study was to evaluate the predictive value of IgG avidity test in the early diagnosis of congenital toxoplasmosis (CT) in newborns (NB). The study group consisted of 68 pairs of mothers and their newborns, 43 with acute toxoplasmosis during pregnancy and 25 with negative IgM to Toxoplasma gondii (control group). Patients gave birth in theMaternityHospitalof the Federal University of Goias. We evaluated serum levels of IgM and IgG anti T. gondii, and avidity IgG. The newborns in the study group were divided into newborns with low avidity (LA) and newborns with high avidity (HA). Concordance of avidity test was verified between the NB and mothers. Infection with T. gondii was observed in 94.1% of newborns with LA and 42.3% of newborns with HA. The levels of IgG and IgM of newborns with LA and their infected mothers were high and showed differences when compared with the not infected newborns (p=0.0001) and their mothers. The symptoms of CT were observed in 56% of the newborns with LA and 18% of the newborns with HA. Our data show that newborns with LA present increased levels of IgM and IgG, and severe symptoms of CT. Thus the avidity test could be used in conjunction with the detection of IgM and IgG for the early diagnosis of TC in NB.