Evaluation of the diagnostic performance of a commercial ELISA based on two recombinant antigens for the diagnosis of Strongyloides stercoralis infection.

Authors

Ángel Gustavo Guevara, Yosselin Vicuña, Mariella Anselmi, Monica Marquez, Francisco Robinzón Huerlo, Matteo Valerio, Cristina Mazzi, Francesca Tamarozzi, Dora Buonfrate

Published in

Parasites & vectors. Jul 04, 2026. Epub Jul 04, 2026.

Abstract

The WHO guideline for the public health control of Strongyloides stercoralis recommends the deployment of Baermann or agar plate culture to estimate the infection prevalence. However, the guideline includes the possible use of antibody-based assays, which might be preferred in some countries. An ELISA based on two recombinant antigens (Strongy Detect ELISA by InBios), performed on dried blood spots (DBS), demonstrated suitable for use in a diagnostic study carried out in remote areas of Ecuador ("ESTRELLA"). A new version of that assay, which aimed at improving specificity according to the indications reported in the target product profile (TPP) for the diagnostics for S. stercoralis, was recently made available in the market. Aim of this study was to compare the performance of the two versions of that ELISA.
The DBS collected in the context of the study in Ecuador were tested with the new ELISA. Sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively) were calculated with Bayesian Latent Class Analysis (BLCA). Bayesian estimates were reported as posterior medians with corresponding 95% credible intervals (CrI). Test agreement was calculated with both BLCA and Cohen's kappa.
Sensitivity was 66.7% (95% CrI 52.8-80.6) for the new assay, versus 78.8% (95% CrI 66.7-89.2) of the old version (posterior probability that the new test had higher sensitivity = 0.1). Specificity was markedly higher for the new version compared to the previous assay: 98.8% (95% CrI 97.9-99.4) versus 90.1% (95% CrI 87.6-92.4), respectively (posterior probability that the new test had higher specificity = 1). PPV for the new ELISA proved good at all prevalence values considered, going from 80.1% (CrI 67.0-89.4%) when prevalence was 7% to 95.8% (92.5%, 97.9%) with 30% prevalence. The agreement was fair (Cohen's kappa 0.38; 95% CI 0.26-0.49).
The new version of the Strongy Detect ELISA demonstrated improved specificity with a moderate reduction in sensitivity compared to the previous version, meeting the TPP requirements in terms of diagnostic performance. Adherence with the other TPP requirements was out of the scope of this study, and should be assessed elsewhere.

PMID:
42401974
Bibliographic data and abstract were imported from PubMed on 05 Jul 2026.

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