The probability of transmission of toxoplasmosis to the fetus varies according to the gestational period in which the mother has contracted the infection: the risk is low at the beginning of pregnancy and increases with the progress of time. On the contrary, the severity of the damage reported by the child is greater, as soon as the maternal-fetal transmission occurs. In cases of infection contracted within the sixth month of gestation, a spontaneous abortion, a premature birth or the birth fetus may present chorioretinitis, hydrocephalus (or microcephaly) and intracranial calcifications. These neurological signs can be associated with skin eruptions, atrophy of the optic nerve, nystagmus, jaundice, myocarditis and pneumonia.
In the case of probable and ascertained maternal toxoplasmosis from the Toxo test, to know if Toxoplasma gondii has actually crossed the placental barrier and infected the child, an amniocentesis is indicated (not before the 15th week of pregnancy). The sample of amniotic fluid taken during the investigation and subjected to PCR (polymerase chain reaction) allows to confirm the possible presence of the DNA of the parasite, thus diagnosing fetal infection. On the other hand, echographic monitoring may show clear signs of fetal damage (intracranial calcifications, hydrocephalus, hepatomegaly, intrauterine growth retardation). After birth, the suspicion of congenital toxoplasmosis is confirmed essentially by serological investigations and by the presence of signs of disease, which can appear even years later, especially in the absence of therapy.
