FDA clears first test for recent toxoplasmosis infection

May 26, 2011

The United States Food and Drug Administration has cleared the first test to establish whether people who test positive for toxoplasmosis acquired the infection within the past 4 months. Toxoplasmosis is commonly contracted by consuming raw, undercooked, or contaminated meat or from contact with cat feces or litter.

The United States Food and Drug Administration has cleared the first test to establish whether people who test positive for toxoplasmosis acquired the infection within the past 4 months. Toxoplasmosis is commonly contracted by consuming raw, undercooked, or contaminated meat or from contact with cat feces or litter.

Women infected with the Toxoplasma gondii parasite shortly before or during pregnancy can transmit the infection to the fetus, leading to miscarriage, stillbirth, or an abnormally small or large head as well as vision loss, mental disability, and seizures later in the child’s life. Immunocompromised individuals are also at risk of serious health problems from the infection, which is marked by swollen lymph nodes and flu-like symptoms.

“Toxoplasmosis can have serious and lasting health consequences for infants that acquire the infection in the womb,” says Alberto Gutierrez, PhD, director of the Office of In Vitro Diagnostic Device Evaluation and Safety in the FDA's Center for Devices and Radiological Health. “This test gives doctors an additional tool to determine if women with confirmed cases of toxoplasmosis acquired the infection before or during pregnancy.”

The VIDAS TOXO IgG Avidity Assay (bioMerieux; Hazelwood, Missouri) measures how strongly immunoglobulin G (IgG) avidity antibodies bind to the T gondii antigens in the assay. Antibodies from infections acquired at 4 or fewer months previously form weaker bonds than infections older than 4 months. The test is indicated for people with confirmed T gondii infection who are pregnant or who have swollen lymph glands, but should not be used as the sole basis for clinical decisions.

The performance of the assay has not been established for prenatal screening, immunocompromised patients, or toxoplasmosis reinfection or relapse. It is not cleared or approved for screening of blood or plasma donors.