What is Congenital Toxoplasmosis?

Posted On: March 2, 2017 By Nathan D. Fox, MD

A type of parasite called Toxoplasma gondhii causes toxoplasmosis. The infection can be acquired by humans when eating undercooked meat of infected animals, insect contamination of food, contact with toxoplasma in the feces of infected cats, or by infected materials in soil.

Toxoplasmosis Infection of Adults and Pregnant Women

Infections for adults are typically asymptomatic, however, non-specific symptoms may occur. Parasitemia may occur, and in pregnant women, this can seed the placenta and infect the fetus. Congenital infection occurs in 10 to 15 percent of cases of first-trimester exposure, with higher rates seen later in pregnancy. The earlier the fetal infection develops, the more severe the disease.

Some consequences can be seen in the majority of cases, including chorioretinitis (leading to vision impairment), hearing loss, hydrocephalus, and mental defects. Stillbirth and neonatal death are rare in these cases.

Likelihood and Prevention of Congenital Infection

If infection precedes pregnancy, the risk for congenital toxoplasmosis would be very low. Spiramycin, a macrolide antibiotic, is used widely in Europe and is recommended by some infectious disease experts. However, this is not approved for the use in the United States, though the FDA will release this medication upon the recommendation of the reference laboratory in Palo Alto.

Spiramycin concentrates in the placenta, and may reduce the incidence of transplacental pass of toxoplasmosis infection by 60 percent. However, while it’s not clear that this medication will be of benefit, it is well tolerated, and is unlikely to be associated with harmful side effects.

Prenantal Diagnosis of Toxoplasmosis

Amniocentesis should be performed at 18+ weeks to test the amniotic fluid via PCR for toxoplasmosis, which will identify a fetal infection. The sensitivity of this test is approximately 80 to 90 percent. Second-trimester ultrasound tests in New York can detect evidence of congenital toxoplasmosis in some cases. Ultrasound findings that are suspicious may include microcephaly, fetal growth restriction, periventricular calcifications or calcifications of the liver, and more.

If there is evidence of fetal infection, treatment is recommended, which includes medications that can cross the placenta and treat fetal infection, including sulfadiazine, pyrimethamine, and folinic acid. However, it still is uncertain if these medications are more effective than spiramycin or effective at all in reducing the risk of transmission.

For more information, contact Carnegie Imaging or visit our blog.

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

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