[The Spanish Society of Pediatric Infectious Diseases Guidelines for the diagnosis and treatment of congenital toxoplasmosis].

Congenital toxoplasmosis is the result of transplacental fetal infection by Toxoplasma gondii after the primary maternal infection. The severity of the disease depends on the gestational age at transmission. First trimester infections are more severe, but less frequent, than third trimester infections. Acute maternal infection is diagnosed by seroconversion or by the detection of IgM antibodies and a low IgG avidity test. In these cases, spiramycin should be initiated to prevent transmission to the fetus. For identification of fetal infection, polymerase chain reaction (PCR) testing of amniotic fluid after 18 weeks gestation should be performed. If fetal infection is confirmed, the mothers should be treated with pyrimethamine, sulfadiazine and folinic acid. Most infants infected in utero are born with no obvious signs of toxoplasmosis, but up to 80% developed learning and visual disabilities later in life. Neonatal diagnosis with IgM/IgA antibodies or blood/cerebrospinal fluid PCR may be difficult because false-negative results frequently occur. In these cases diagnosis is possible by demonstrating a rise in IgG titers during follow-up or by the detection of antibodies beyond one year of age. Early treatment with pyrimethamine and sulfadiazine may improve the ophthalmologic and neurological outcome. Congenital toxoplasmosis is a preventable disease. Pre-pregnancy screening and appropriate counseling regarding prevention measures in seronegative women may prevent fetal infection.