title: Interpretation of the Elecsys Toxo IgG avidity results for very low and very high index: study on 741 sera with a determined date of toxoplasmosis.
abstract: Initial results with the Elecsys Toxo IgG Avidity assay showed some potential for interpretation of a very low or very high index result. We aimed to examine these new insights into interpretation using a large panel of serum samples and to define the optimal thresholds. A total of 741 patient serum samples with known date of infection (from a few weeks to more than 9 months after infection), were analysed with the Elecsys Toxo IgG Avidity assay. Values ≥80% (threshold defined by the manufacturer) were reported in 289 sera; 288 sera were sampled more than 4 months after infection. Thus, avidity values ≥80% excluded an infection less than 4 months. Avidity values ≥90% were reported in 112 sera sampled more than 9 months after infection. Thus, avidity values ≥90% excluded infection less than 9 months. Moreover avidity values ≤15% were reported in the 62 sera sampled less than 3 months after infection. Thus avidity values ≤15% excluded infection more than 3 months.
authors.affiliation: Laboratory of Parasitology and Mycology, Grenoble University Hospital and Grenoble Alpes University, CS10217, 38043, Grenoble Cedex 9, France. hfricker-hidalgo@chu-grenoble.fr.
authors.forename: H
authors.identifier: http://orcid.org/0000-0002-1932-2531
authors.initials: H
authors.lastname: Fricker-Hidalgo
authors.affiliation: Laboratory of Parasitology and Mycology, La Timone University Hospital and UMR MD3 IP-TPT Aix Marseille University, Marseille, France.
authors.forename: C
authors.initials: C
authors.lastname: L'Ollivier
authors.affiliation: Laboratory of Parasitology and Mycology, Grenoble University Hospital and Grenoble Alpes University, CS10217, 38043, Grenoble Cedex 9, France.
authors.forename: C
authors.initials: C
authors.lastname: Bosson
authors.affiliation: Laboratory of Parasitology and Mycology, AP-HP, Pitié Salpêtrière/Charles Foix University Hospital, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Imbert
authors.affiliation: Laboratory of Parasitology and Mycology, Grenoble University Hospital and Grenoble Alpes University, CS10217, 38043, Grenoble Cedex 9, France.
authors.forename: S
authors.initials: S
authors.lastname: Bailly
authors.affiliation: Laboratory of Parasitology and Mycology, Grenoble University Hospital and Grenoble Alpes University, CS10217, 38043, Grenoble Cedex 9, France.
authors.forename: C
authors.initials: C
authors.lastname: Dard
authors.affiliation: Laboratory of Parasitology and Mycology, La Timone University Hospital and UMR MD3 IP-TPT Aix Marseille University, Marseille, France.
authors.forename: R
authors.initials: R
authors.lastname: Piarroux
authors.affiliation: Laboratory of Parasitology and Mycology, AP-HP, Pitié Salpêtrière/Charles Foix University Hospital, Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Paris
authors.affiliation: Laboratory of Parasitology and Mycology, Grenoble University Hospital and Grenoble Alpes University, CS10217, 38043, Grenoble Cedex 9, France.
authors.forename: H
authors.initials: H
authors.lastname: Pelloux
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood*; D000915:Antibody Affinity; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood*; D011247:Pregnancy; D013997:Time Factors; D014123:Toxoplasmosis / Q000175:diagnosis* / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G