Toxoplasmosis. Congenital Toxoplasmosis

Congenital infection can occur if a woman develops acute toxoplasmosis during pregnancy. Chronic or latent infection is unlikely to cause fetal injury except perhaps in an immunosuppressed patient. Approximately 40 percent of neonates born to mothers with acute toxoplasmosis show evidence of infection. Congenital infection is most likely to occur when maternal infection develops in the third trimester. Less than half of affected infants are symptomatic at birth. The clinical manifestations of congenital toxoplasmosis are quite varied and are summarized below. [216] [217] [218]

The most valuable tests for antenatal diagnosis of congenital toxoplasmosis are ultrasound, cordocentesis, and amniocentesis. Ultrasound findings suggestive of infection include ventriculomegaly, intracranial calcifications, microcephaly, ascites, hepatosplenomegaly, and growth restriction. Fetal blood samples can be tested for IgM-specific antibody after 20 weeks' gestation. Fetal blood and amniotic fluid can be inoculated into mice, and the organism can subsequently be recovered from the blood of infected animals. In addition, Hohlfeld et al. [219] have now identified a specific gene of T. gondii in amniotic fluid using a polymerase chain reaction test. In their investigation, 34 of 339 infants had congenital toxoplasmosis confirmed by serologic testing or autopsy. All amniotic fluid samples from affected pregnancies were positive by polymerase chain reaction. Test results were available within 1 day of specimen collection.

Clinical Manifestations of Congenital Toxoplasmosis

Rash

Hepatosplenomegaly

Ascites

Fever

Chorioretinitis

Periventricular calcifications

Ventriculomegaly

Seizures

Mental retardation

Uveitis

Management

Toxoplasmosis in the immunocompetent adult is usually an asymptomatic or self-limited illness and does not require treatment. lmmunocompromised patients, however, should be treated, and the regimen of choice is a combination of oral sulfadiazine (4 g loading dose, then 1 g four times daily) plus pyrimethamine (50 to 100 mg initially, then 25 mg daily). In such patients, extended courses of treatment may be necessary to cure the infection.

Treatment also is indicated when acute toxoplasmosis occurs during pregnancy. Treatment of the mother clearly has been shown to reduce the risk of congenital infection and decrease the late sequelae of infection. [217] [218] Pyrimethamine is not recommended for use during the first trimester of pregnancy because of possible teratogenicity. Sulfonamides can be used alone, but single agent therapy appears to be less effective than combination therapy. In Europe, spiramycin, a macrolide antibiotic, has been used extensively in pregnancy with excellent success. [217] [218] It is available for use in the United States through the CDC.

Aggressive early treatment of infants with congenital toxoplasmosis is indicated and consists of combination therapy with pyrimethamine, sulfadiazine, and leucovorin for 1 year. [220] Early treatment reduces, but does not eliminate, the late sequelae of toxoplasmosis such as chorioretinitis.

In the management of the pregnant patient, prevention of acute toxoplasmosis is of paramount importance. Pregnant women should be advised to avoid contact with stray cats or cat litter. They should always wash their hands after preparing meat for cooking and should never eat raw or rare meat. Fruits and vegetables also should be washed carefully to remove