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

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

doi:10.1186/s13071-022-05249-z

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

Parasit Vectors. 2022 Apr 23;15(1):142. doi: 10.1186/s13071-022-05249-z.

Authors

Francesca Tamarozzi¹, Silvia Stefania Longoni¹, Cristina Mazzi², Eleonora Rizzi¹, Rahmah Noordin³, Dora Buonfrate⁴

Affiliations

¹ Department of Infectious Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, 37024, Negrar, Verona, Italy.
² Clinical Research Unit, IRCCS Sacro Cuore Don Calabria Hospital, 37024, Negrar, Verona, Italy.
³ Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800, Penang, Malaysia.
⁴ Department of Infectious Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, 37024, Negrar, Verona, Italy. dora.buonfrate@sacrocuore.it.

Abstract

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.

Keywords: Diagnostic study; Immunochromatographic test; Rapid diagnostic test; Recombinant antigen; Strongyloides; Strongyloidiasis.

MeSH terms

Animals
Enzyme-Linked Immunosorbent Assay / methods
Feces / parasitology
Humans
Immunologic Tests
Sensitivity and Specificity
Strongyloides stercoralis*
Strongyloidiasis* / parasitology
Transients and Migrants*