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Licensed Unlicensed Requires Authentication Published by De Gruyter April 24, 2020

Performance of a Toxo IgM prototype assay for the diagnosis of maternal and congenital Toxoplasma infections

Martine Wallon, Hélène Fricker-Hidalgo, Emmanuelle Chapey, Claire Bailet, Céline Dard, Marie-Pierre Brenier-Pinchart and Hervé Pelloux

Abstract

Background

Testing for anti-Toxoplasma immunoglobulin (Ig)M is of main importance in the context of pregnancy to promptly alert to an acute maternal infection prior to the detection of IgG and to identify infected newborns. Their absence helps exclude a recent maternal infection in the presence of IgG.

Methods

The performance of a Toxo IgM immunocapture prototype assay (bioMérieux, France) was compared with that of the VIDAS® Toxo IgM and the ARCHITECT® Toxo IgM (Abbott, Germany) assays at Grenoble and Lyon (France). A total of 1446 sera were sampled from (i) 1054 pregnant women found by routine workup to have no infection (n = 843), an acute infection (<4 months) (n = 28) or a chronic infection (>4 months) with residual (n = 120) or no IgM (n = 62); (ii) 50 three-serum panels sampled immediately after a maternal seroconversion; (iii) 242 samples taken in 41 children with a congenital toxoplasmosis (n = 122) and in 40 uninfected children (n = 120).

Results

In pregnant women, the overall agreement with the VIDAS® assay was 99.23% (CI: 99.16–99.27) and that with the ARCHITECT® assay was 99.14% (CI: 99.07–99.17). Sensitivity of the Toxo IgM prototype assay was 100% (CI: 87.66–100.00) and specificity was 99.64% (98.96–99.93). In acute maternal infections, IgM assays were detected as early with the prototype as with the other two. In the congenitally infected children, IgM were detected on their first sample in 25/40 with the prototype vs. 23/40 with the VIDAS® test. No uninfected child had positive IgM.

Conclusion

The prototype performed comparably to the ARCHITECT® and VIDAS® Toxo IgM assays for the diagnosis of maternal and congenital toxoplasmosis.


Corresponding author: Martine Wallon, Service de Parasitologie et de Mycologie Médicale, Hôpital de la Croix Rousse, CHU de Lyon, Lyon, France; and Faculté de Médecine Lyon-Sud, Waking Team, Centre de Recherche en Neurosciences de Lyon, INSERM U1028-CNRS UMR 5292, Université Claude Bernard Lyon 1, Lyon, France

  1. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  2. Research funding: None declared.

  3. Employment or leadership: None declared.

  4. Honorarium: None declared.

  5. Competing interests: Authors state no conflict of interest.

  6. Ethical approval: The study protocol was approved by the “Comité de Protection des Personnes” of Lyon.

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Received: 2019-11-20
Accepted: 2020-03-26
Published Online: 2020-04-24
Published in Print: 2020-10-25

©2020 Walter de Gruyter GmbH, Berlin/Boston

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