Immunoassay for the qualitative determination of T. gondii IgG avidity
Toxoplasmosis is a common infection caused by the protozoan Toxoplasma gondii (T. gondii).1 Healthy individuals generally have mild or no symptoms, however, if primary infection occurs during pregnancy, it can result in severe damage to the fetus.1
The risk of fetal damage is highest when the infection is acquired early in pregnancy, while the risk of transmitting the infection increases if the infection is acquired later in the pregnancy.1 Early treatment in acute infection during pregnancy can prevent or ameliorate congenital damage1.
The diagnosis of T. gondii infection starts with the detection of anti-Toxoplasma IgG and IgM antibodies. Toxoplasma IgG avidity test is performed to date the infection. The antibodies produced during the primary response have a lower avidity than those produced during the non-primary response, hence a high avidity early in gestation suggests that infection has taken place more than 4 months ago and rules out a recent primary acute infection.2 However, no clinical interpretation can be deduced from a low or grey-zone avidity result2.