Clinical value of serology for the diagnosis of strongyloidiasis in travelers and migrants: A 4-year retrospective study using the Bordier IVD^®Strongyloides rattiELISA assay

Abstract

Strongyloides stercoralis serology is a sensitive method for strongyloidiasis diagnosis, but it is prone to cross-reactions with other helminthiases. This four-year retrospective study aimed at estimating the performance of the Bordier IVD® Strongyloides ratti ELISA assay in a non-endemic country (France). The study included all patients tested for strongyloidiasis in our center between 2015 and 2019, by both serology and stool examination. Cases were defined using an algorithm considering serological results, microscopic examination of stools, and other biological, clinical or epidemiological data. The study included 805 stools from 341 patients (70% migrants, 20% travelers, 10% without travel to a highly endemic area). Thirty patients (8.8%) had positive serology, 9 had microscopically proven strongyloidiasis, and 11 and 10 were classified as probable and possible strongyloidiasis, respectively. Performances of microscopy and serology were compared, considering proven and probable strongyloidiasis as true infections. The sensitivity, specificity, positive predictive value and negative predictive value of serology were 100%, 97%, 67% and 100%, respectively, and those of microscopic examination of stools were 45% (p < 0.01), 100% (p < 0.01), 100% (p = 0.079) and 96% (p < 0.001), respectively. Eosinophilia did not help in discriminating true-positive from false-positive results. Overall, these results underline the high value of the S. stercoralis serologic assay, compared to stool examination. The systematic use of this technique for screening purposes in travelers or migrants, or before onset of immunosuppressive therapy, could help to improve patient management and epidemiological knowledge.

Disseminated Strongyloidiasis in a Patient Treated with Rituximab and Ibrutinib, a Case Report

“…Molecular detection of S. stercoralis in stool is also possible using new marketed assays [14,15], but in the setting of hyperinfection, they have poor added value, as larvae detection using standard methods (Baerman funnel technique or agar-plate cultures) is easy. Whereas hypereosinophilia is inconstant in chronically infected immunocompetent patients [2], any hypereosinophilia associated with atypical skin signs should stress the search for strongyloidiasis.…”

“…The disease is widely distributed in tropical and subtropical regions, and it is estimated that 30 to 100 million people are infected worldwide [1]. Strongyloidiasis is asymptomatic in more than half of cases, where eosinophilia or a positive serologic test may be the only finding [2]. The parasite has a long-term persistence in the host leading to infection that could last for decades.…”

Serological diagnosis of strongyloidiasis: An evaluation of three commercial assays

“…This bias is strongest in endemic areas, but can also affect non-endemic regions, if mainly migrants or refugees from endemic regions are included. A recent retrospective study from France, for example, included 30 proven, probable or possible strongyloidiasis cases, of which 21 were from migrants and nine from travelers; among the latter, only two were microscopically confirmed cases [ 26 ]. The authors´ conclusion that the tested assay ( Strongyloides ratti ELISA, Bordier) was a highly sensitive tool for the diagnosis and screening of travelers seems overly optimistic.…”

Evaluation of Commercial Concentration Methods for Microscopic Diagnosis of Protozoa and Helminths in Human Stool Samples in a Non-Endemic Area

“…By restricting microscopic methods to helminth detection, this strategy would save time, as it allows one to reduce the number of concentration methods used and to examine mounted slides under a microscope at 10-fold magnification, which is rapid and easy. However, it should be remembered that Strongyloides stercoralis larvae are not concentrated by diphasic methods, and adequate methods or serological techniques should be combined when necessary [22,23].…”