Time before anti-Toxoplasma IgG seroconversion detection by 7 commercial assays in French pregnant women

- Six hundred twenty sera (269 seroconversions) were analyzed for the detection of anti-Toxoplasma IgG.
- The variable used to compare the assays was the median time to IgG detection.
- Architect® and TGS TA® were the earliest (>10 days before the other screening tests).
- The study confirms the ability of LDBIO® to be a confirmatory test.
- Our results cannot be applied to latent infection.

We assessed the ability to early detect a toxoplasmic seroconversion between 1 immunoblot (LDBIO II®) and 6 automated assays (TGS TA®, Architect®, Vidas II®, Liaison II®, Platelia®, and Elecsys®), comparing the time before anti-Toxoplasma gondii IgG detection during infection in pregnant women. From 2007 to 2015, 620 sera of 269 women were included. The median durations before positive IgG detection with Vidas II®, Liaison II®, Platelia®, and Elecsys® were significantly longer than Architect® with differential times from 11 to 28 days (P < 0.001). This time was significantly shortened by the use of LDBIO®, resulting in a saving of 13 days (P < 0.001). The detection of a positive rate of IgG with TGS TA® was as early as Architect® (P = 0.105). The ability to early detect a toxoplasmic seroconversion is not equivalent between the assays and has to be considered when selecting the reagents to reduce the time to therapeutic intervention.

160