2136. Toxoplasma gondii, IgA antibodies

IgA antibodies to Toxoplasma gondii appear early in the infection and may indicate acute or recent infection. The test is used to diagnose toxoplasmosis, especially in pregnant women and newborns, and when IgM levels are questionable.

Thoxoplasma gondii is an intracellular parasite that causes toxoplasmosis. The infection is usually asymptomatic in healthy individuals, but can pose a significant risk to pregnant women, the fetus (congenital toxoplasmosis), and patients with immunosuppression (HIV, cancer, transplantation).

IgA antibodies appear:

• early – soon after infection;
• may be present even with a negative IgM;
• indicate an acute or recent phase of infection;
• sometimes persist longer than IgM, especially in newborns.

Clinical significance:

• IgA (+) in combination with IgM and/or low-avidity IgG → high probability of acute toxoplasmosis.
• IgA (+) with a negative IgM → possible recent infection, requires additional testing (IgG avidity, repeat testing).
• In infants, IgA may be evidence of congenital infection, as these antibodies are not transferred placentally.

• Pregnant women – if primary infection during pregnancy is suspected or if IgM/IgG results are inconclusive.
• Newborns – for the diagnosis of congenital toxoplasmosis.
• Immunosuppressed patients – for systemic lesions (CNS, eyes, lungs) of unknown origin.
• In case of IgG seroconversion or if IgM persists for a long time without clinical manifestations.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: