[Congenital toxoplasmosis: transmission to the fetus of a pre-pregnancy maternal infection].

It has been established that maternal immunity developing before conception protects the fetus from congenital toxoplasmosis. We observed a case of congenital toxoplasmosis consecutive to a maternal toxoplasma infection that had preceded pregnancy. A woman with normal immune system developed toxoplasmosis 2 months before conceiving. No treatment was given to this prepregnancy seroconverted patient. At 25 weeks of amenorrhoea, the ultrasound examination showed a fetal cerebral ventricular dilatation. Amniocentesis and cordocentesis showed fetal toxoplasmosis infection. Fetopathologic examination confirmed the diagnosis of cerebral toxoplasmosis. The pathophysiology of maternal-fetal toxoplasma transmission and the role played by maternal immunodeficiency are discussed. This exceptional case-report showed the difficulties of the management in patients with 3-month pre-pregnancy toxoplasmosis and its practical implications.