The US Food and Drug Administration has cleared the first test to determine the timing of infection in individuals who are pregnant or have swollen lymph glands and who have been confirmed to be infected with the parasite Toxoplasma gondii, which causes toxoplasmosis (http://tinyurl.com/3u7op5o).
The VIDAS TOXO IgG Avidity assay detects how strongly IgG avidity antibodies bind to T gondii antigens: antibodies from infections that occurred more than 4 months earlier bind more tightly with the antigens than do those from infections acquired in the past 4 months.
Hampton T. Toxoplasmosis Test. JAMA. 2011;305(24):2510. doi:10.1001/jama.2011.869