[Question marks concerning serological tests in congenital toxoplasmosis - a case report].

Two weeks after delivery of a healthy term neonate, the mother developed lymph node syndrome, which corresponded serologically to acute toxoplasmosis. The blood of the newborn showed positive IgM, IgG and IgA antibody titers against Toxoplasma gondii with a low avidity of IgG. The newborn did not show any clinical signs or organ damage connected to toxoplasmosis either at the beginning or during the follow-up. The IgA and IgM titers exhibited a decrease over time, while the KFR, IgG antibody titers and avidity had an increasing trend. A sharp increase of KFR, IgE and IgA antibody titers was detected during the sixth month of life, probably due to maturation of the immune system in the setting of an asymptomatic infection with T. gondii. This short increase was followed by a subsequent decrease in titers of these antibodies until they reached negative levels during the 21st month of life. The evaluation of serological results in newborns infected with T. gondii is always difficult and should be performed by an expert physician. Children at risk should be placed under a long-term follow-up to avoid potential development of toxoplasma chorioretinitis.