Help in the Choice of Automated or Semiautomated Immunoassays for Serological Diagnosis of Toxoplasmosis: Evaluation of Nine Immunoassays by the French National Reference Center for Toxoplasmosis

Abstract

h Toxoplasmosis, a benign infection, is asymptomatic or paucisymptomatic in over 80% of cases, except in immunocompetent patients suffering from ocular toxoplasmosis or in immunocompromised patients with opportunistic or congenital toxoplasmosis. Diagnosis is based mainly on serology testing. Thus, we compared the performance of the nine most commonly used commercial automated or semiautomated immunoassays for IgG and IgM Toxoplasma gondii antibody detection, that is, the Advia Centaur, Architect, AxSYM, Elecsys, Enzygnost, Liaison, Platelia, VIDAS, and VIDIA assays. The assays were conducted on four panels of serum samples derived during routine testing from patients with an interfering disease and who exhibited a low IgG antibody level in one of two clinical settings, namely, acute or chronic toxoplasmosis. As a result, IgG sensitivities ranged from 97.1% to 100%, and IgG specificities ranged from 99.5% to 100%. For IgG quantification, strong differences in IgG titers (expressed in IU/ml) were noted depending on the assay used. IgM sensitivities ranged from 65% to 97.9%, and IgM specificities ranged from 92.6% to 100%. For defining the best serological strategies to be implemented, it appears crucial to compare the diagnostic performance of the different tests with respect to their specificity and sensitivity in detecting the presence of IgG and IgM antibodies.

Toxoplasma gondii Infection in the United States, 2011–2014

“…The Platelia Toxo IgM test used in this study is a commonly used commercial test; a recent evaluation in France reported it had the highest sensitivity (97.9%) of nine tests evaluated, and it had a specificity of 92.6% when compared with two different validation methods (immunofluorescence assay-M and immunosorbent agglutination assay [ISAGA-M bioMerieux ® SA, 89 Marcy l'Etoile, France]) at a reference laboratory. 27 However, in this French study population, the Platelia Toxo IgM predictive value positive was 63%, so it is possible that our results over estimate IgM antibody prevalence. Toxoplasma gondii IgM tests are designed by manufacturers to have high sensitivity at the cost of specificity to limit the risk of missing acute infections.…”

Evaluation of Serological and Molecular Tests Used for the Identification of Toxoplasma gondii Infection in Patients Treated in an Ophthalmology Clinic of a Public Health Service in São Paulo State, Brazil

“…These findings may suggest that those IgM results detected by ELISA could be a result of persistence of Toxoplasma IgM in chronic infection. False positive results might be troublesome specially during prenatal care, as it could lead to undesirable consequences and unnecessary treatment and interventions, therefore, assays which do not detect these residual IgM antibodies would be ideal (Dhakal et al, 2015;Villard et al, 2016). Unfortunately, we just had access to one sample of these patients and consequently no follow-up was performed.…”

Evaluation of a New Immunochromatography Technology Test (LDBio Diagnostics) To Detect Toxoplasma IgG and IgM: Comparison with the Routine Architect Technique

“…In this study, we assessed the performance of the immunochromatography technology (ICT) Toxoplasma IgG and IgM rapid diagnostic test (LDBio Diagnostics, France) and compared the results with those of the Architect system. This automated technique is reliable for first-line serodiagnosis (6) and was chosen as the screening technique in Saint-Etienne and Marseille. This assessment is critical to define a good serological strategy based on the specificity and sensitivity of the two techniques.…”