Abstract
A maternal Toxoplasma gondii infection during pregnancy is a risk for congenital infection through maternal-fetal transplacental transmission. Estimation of the date of infection is of the utmost importance for management and treatment recommendations. In this setting, IgG avidity has been shown to be useful as high avidity rules out an infection dating less than 4 months. The estimated date of infection can also be obtained by the ratio of T. gondii IgG titers measured by the Vidas (bioMérieux) assay versus T. gondii IgG titers measured by the Architect (Abbott Laboratories) test, together with T. gondii IgM and IgA antibody responses. In this study, using 117 serum samples from pregnant women, we compared the IgG avidity values obtained by Architect and Vidas with the presumed date of T. gondii infection established by the T. gondii IgG ratio of IgG Vidas and IgG Architect plus the IgM and IgA results. To date, IgG avidity Vidas seems to exhibit better performance than Architect. For both assays, gray zone results were most likely obtained from patients infected more than 4 months before sampling. These data should be taken into account for a possible reconsideration of the interpretation of avidity results in the gray zone.
Highlights
Toxoplasma gondii is an obligate intracellular protozoan parasite that infects most species of warm-blooded animals, including humans
The aim of this study was to compare the estimated date of infection obtained by the IgG ratio described above with the estimated date of infection obtained by the T. gondii avidity assays Architect and Vidas
For the 17 sera classified in group AI < 4, the low avidity values were in agreement with the estimated date of infection expect for one Vidas avidity classified in the gray zone
Summary
Toxoplasma gondii is an obligate intracellular protozoan parasite that infects most species of warm-blooded animals, including humans. A primary maternal infection acquired during pregnancy can lead to a risk of congenital infection. This risk is moderate (4–14%) if maternal infection occurs in the first. The severity of congenital infection is higher if fetal infection occurs earlier in pregnancy (intrauterine fetal death, intracranial calcifications, and hydrocephalus) [5]. Infections around birth are frequently asymptomatic [5]
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