Toxoplasma gondii, a mammal-borne parasite can cause serious fetal damage, especially if the infection occures during the first or second trimester (the risk is 10 – 40%).
The congenital infection manifests itself through a typical triad: hydrocephalus, chorioretinitis and intracranial calcifications. Infection can also be found in other organs such as the lungs, the liver, the heart, kidneys, adrenal glands and skeletal muscle. In the CNS necroses of the cortex and basal ganglia are sometimes present.
The inflammatory infiltrate consists of histiocytes and lymphocytes. Later calcifications are present. Cystic forms of parasite are PAS-positive. We can find them in the embryonal tissues, the placenta, membranes and the umbilical cord as well. In extraembryonal tissues microorganism can be most easily detected if infection occured during the 3rd trimester. Other manifestations include villous edema and fibrosis.
Toxoplasmosis, congenital hydrocephalus, 4 day infant: Toxoplasmosis, congenital hydrocephalus, HE 100x (71997)