Diagnostic Accuracy of a Novel Chemiluminescent Immunoassay for Strongyloides stercoralis in a Non-Endemic Clinical Setting

Background/Objectives: Strongyloides stercoralis is a soil-transmitted helminth that can cause severe disease in immunocompromised individuals. In non-endemic clinical settings, recommended diagnostic strategies rely on serology alone or in combination with a sensitive fecal test, maximizing sensitivity to avoid missed infections. The S. stercoralis VirClia® IgG monotest (Vircell, Spain) is a novel automated chemiluminescent immunoassay (CLIA) that detects IgG antibodies against the recombinant NIE and SsIR antigens. This study evaluated its diagnostic accuracy (sensitivity and specificity) in a non-endemic clinical setting. Methods: In this monocentric retrospective study, 245 serum samples from the Tropica Biobank of a referral centre for parasitic diseases in Italy were analyzed. Samples originated from individuals from Africa (n = 85), America (n = 31), Asia (n = 53), and Europe (n = 76). Diagnostic accuracy was estimated using Bayesian latent class analysis based on a model including five routinely used diagnostic tests. Results: The S. stercoralis VirClia® IgG monotest showed a sensitivity of 95.0% (95% credible interval [CrI]: 90.1–98.2%) and a specificity of 90.8% (95% CrI: 85.1–96.0%) for the tested population. Conclusions: In immunocompetent individuals with a risk of previous exposure to S. stercoralis, the S. stercoralis VirClia® IgG monotest showed high diagnostic accuracy. Its high sensitivity supports current recommendations favouring highly sensitive serological assays for screening and diagnosis in non-endemic clinical settings.