Journal Article

The accuracy of a recombinant antigen immunochromatographic test for the detection of Strongyloides stercoralis infection in migrants from sub-Saharan Africa

Rizzi, Eleonora, Noordin, Rahmah, Buonfrate, Dora, Mazzi, Cristina, Tamarozzi, Francesca, Longoni, Silvia Stefania

2022

Overview

Background Strongyloidiasis, a nematode infection which is mainly caused by Strongyloides stercoralis in humans, can lead to a fatal syndrome in immunocompromised individuals. Its diagnosis is challenging due to the absence of a diagnostic gold standard. The infection is highly prevalent in migrants from endemic countries in tropical and subtropical areas, and a rapid diagnostic test would be helpful for screening purposes. The aim of this study was to estimate the accuracy of a novel immunochromatographic test (ICT) for the diagnosis of S. stercoralis infection. Methods A single-centre diagnostic accuracy study was undertaken using well-characterized frozen sera available from the biobank of a referral hospital for parasitic diseases in Italy. The included sera were from migrants from sub-Saharan Africa, and matching results were available for agar plate culture and/or polymerase chain reaction for S. stercoralis ; moreover, the results of both a commercial enzyme-linked immunosorbent assay test and an in-house immunofluorescence test for strongyloidiasis were made available. Laboratory staff who read the ICT results were blinded as regards the results of the other tests. Two readers independently read the ICT, and a third one was involved when results were discrepant. The accuracy of the ICT was assessed both against the results of the panel of faecal tests and by latent class analysis (LCA). Results Agreement between the readers was excellent [Cohen’s κ = 92.7%, 95% confidence interval (CI) 88.3–97.1%]. When assessed against the results of the faecal tests, the sensitivity and specificity of the ICT were 82.4% (95% CI 75.7–89.0%) and 73.8% (95% CI 66.8–80.9%), respectively. According to the LCA, the sensitivity and specificity were 86.3% (95% CI 80.1–92.5%) and 73.9% (95% CI 67.0–80.8%), respectively. Conclusions The results of the ICT demonstrated ease of interpretation. The accuracy proved good, though the sensitivity might be further improved for screening purposes. Graphical Abstract

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Accuracy / agar / Animals / Antigens / Biobanks / Biomedical and Life Sciences / Biomedicine / class / confidence interval / Confidence intervals / Diagnosis / Diagnostic study / Diagnostic systems / ELISA / Entomology / Enzyme-linked immunosorbent assay / Enzyme-Linked Immunosorbent Assay - methods / Evaluation / Feces - parasitology / fluorescent antibody technique / Helminths and helminthic diseases / hospitals / Humans / Immigrants / Immune system / immunoaffinity chromatography / Immunochromatographic test / Immunofluorescence / Immunologic Tests / Infections / Infectious Diseases / Italy / Laboratories / Medical examination / Medical testing products / Migrants / Nematodes / Nucleotide sequence / Parasitic diseases / Parasitology / Parasitoses / PCR / Polymerase chain reaction / Rapid diagnostic test / Recombinant antigen / Recombinants / Screening / Sensitivity and Specificity / Specificity / Statistics / Strongyloides / Strongyloides stercoralis / Strongyloidiasis / Strongyloidiasis - parasitology / Sub-Saharan Africa / Testing / Tests / Transients and Migrants / Tropical climate / Tropical diseases / Tropical Medicine / Veterinary Medicine/Veterinary Science / Virology