Strongy Detect: Preliminary Validation of a Prototype Recombinant Ss-NIE/Ss-IR Based ELISA to Detect Strongyloides stercoralis Infection

Abstract

Background Strongyloides stercoralis (Ss) is the etiological agent of strongyloidiasis, a neglected tropical disease of global concern. Laboratory diagnosis of strongyloidiasis is most often based on detection of antibodies against antigens in an enzyme linked immunosorbent assay (ELISA). Herein, we report a preliminary validation study of newly developed IgG4-and/or IgG-based ELISAs to detect strongyloidiasis (Strongy Detect, InBios) incorporating a cock-tail of 2 previously described recombinant antigens, Ss-NIE and Ss-IR. Methods The sensitivity and specificity were determined by using the assay in 150 cryopreserved serum samples from humans known to be Ss infected (n = 74), helminth uninfected (n = 47), or infected with a helminth other than Ss [n = 29). The treatment associated dynamics of antibody detection were then assessed using 35 paired samples obtained before and after definitive therapy. Results The IgG and IgG4 assays were 99% and 96% sensitive, respectively, and 99% and 100% specific, respectively. Neither the IgG or IgG4 assay showed cross reactions with sera from those infected with other helminths. Although ELISA values did decline post-treatment few returned to levels below the cutoff for infection. Conclusion Strongy Detect is the most sensitive and specific commercialized immunoassay for detection of strongyloidiasis. The assay remains positive for greater than a year post-treatment.