When should toxoplasmosis (Toxoplasma gondii infection) testing be performed during pregnancy?

From the Guidelines

Testing for toxoplasmosis during pregnancy is recommended for women with risk factors or symptoms suggesting possible infection, and initial screening should be considered at the first prenatal visit for women with exposure to cat feces, consumption of undercooked meat, gardening without gloves, or travel to high-prevalence areas. The standard testing approach involves serological tests for Toxoplasma-specific IgG and IgM antibodies 1. If initial testing suggests recent infection, follow-up testing with IgG avidity testing helps determine timing of infection relative to pregnancy. Women with confirmed acute toxoplasmosis during pregnancy should be treated with spiramycin (1 g orally three times daily) until delivery, or with pyrimethamine, sulfadiazine, and leucovorin if fetal infection is confirmed after 18 weeks' gestation 1.

Some key points to consider when testing for toxoplasmosis in pregnancy include:

• The importance of testing for women with risk factors or symptoms suggesting possible infection
• The use of serological tests for Toxoplasma-specific IgG and IgM antibodies as the standard testing approach
• The need for follow-up testing with IgG avidity testing if initial testing suggests recent infection
• The recommended treatment options for women with confirmed acute toxoplasmosis during pregnancy, including spiramycin and pyrimethamine, sulfadiazine, and leucovorin.

It is also important to note that congenital toxoplasmosis can cause serious complications, including hydrocephalus, chorioretinitis, and developmental delays in the fetus, while most maternal infections are asymptomatic or mild 1. Therefore, testing and treatment are crucial to prevent these complications. Additionally, primary prevention strategies, such as avoiding contact with cat feces and undercooked meat, can help reduce the risk of toxoplasmosis in pregnant women 1.

In terms of specific guidelines, the American College of Obstetricians and Gynecologists (ACOG) recommends that pregnant women with risk factors or symptoms suggesting possible infection should be tested for toxoplasmosis 1. The Centers for Disease Control and Prevention (CDC) also provides guidelines for the prevention and treatment of toxoplasmosis in pregnant women, including recommendations for testing and treatment 1.

Overall, testing for toxoplasmosis during pregnancy is an important part of prenatal care, particularly for women with risk factors or symptoms suggesting possible infection. By following the recommended testing and treatment guidelines, healthcare providers can help prevent serious complications and ensure the best possible outcomes for pregnant women and their babies.

From the Research

When to Test for Toxoplasmosis in Pregnancy

• Testing for toxoplasmosis in pregnancy is not routinely recommended for all pregnant women, but rather for those considered to be at risk for primary Toxoplasma gondii infection 2.
• Serologic screening should be offered to pregnant women who are at risk, and suspected recent infection should be confirmed before intervention by having samples tested at a toxoplasmosis reference laboratory 2.
• If acute infection is suspected, repeat testing should be performed within 2 to 3 weeks, and consideration given to starting therapy with spiramycin immediately, without waiting for the repeat test results 2.
• Amniocentesis should be offered to identify Toxoplasma gondii in the amniotic fluid by polymerase chain reaction (PCR) if maternal primary infection is diagnosed, or if serologic testing cannot confirm or exclude acute infection, or in the presence of abnormal ultrasound findings 2, 3.

Risk Factors for Toxoplasmosis in Pregnancy

• Consumption of undercooked meat and unprotected contact with soil are independent risk factors for T. gondii seroconversion during pregnancy 4.
• Contact with cat litter may pose a risk in certain situations 5, 4.
• Pregnant women who are immunosuppressed or HIV-positive should be offered screening because of the risk of reactivation and toxoplasmosis encephalitis 2.

Diagnostic Methods for Toxoplasmosis in Pregnancy

• Diagnosis and timing of infection are usually based on serological tests 6.
• The Toxoplasma avidity test can help determine the timing of Toxoplasma gondii infection in relation to pregnancy, but many obstetrician-gynaecologists are not aware of this test 5.
• PCR on amniotic fluid is recommended for prenatal diagnosis when maternal infection is confirmed 3.