Evaluation of enzyme-linked immunosorbaent assay, using somatic and excretory-secretory antigens of strongyloides stercoralis for the serodiagnosis of strongyloidosis

ABSTRACT

Strongyloidiasis, caused by a nematode parasite so-called Strongyloides stercoralis is one of the major human intestinal nematode infections. Considering that stool examination for Strongyloides larvae is not a sensitive method and immunodiagnostic methods are more applicable for this purpose, so the present study was conducted to compare the somatic [S] and excretory - secretory [ES] antigens of Strongyloides stercoralis in IgG-ELISA to diagnose human strongyloidiasis. Serum samples obtained from 50 individuals infected with Strongyloides stercoralis. Sera from healthy control individuals, not infected with any parasitic diseases [n=/30] and from others with different parasitic infections including hydatidosis [n=20], toxocariosis [n=18], ascariasis [n=2], trichostrongylosis [n=10], and hymenolepiasis [n=2] were examined as well. The cut-off point for [S] and ES was 0.48 and 0.36, respectively. Thirty eight and 42 out of 50 individuals infected with Strongyloides stercoralis were also seropositive using [S] and ES antigens, in that order, whereas 15 cases of false positive reactions for [S] and 10 for ES antigen were detected when non-strongyloidiasis sera were examined, therefore the sensitivity of the test was 80.6% and 86.2% for [S] and ES antigens, respectively. The specificity of those antigens was calculated as 84.2% and 88.2%, correspondingly. It was concluded that overall ES antigen showed a more convincing diagnosis in comparison with [S] antigen, although every interpretation of the results should be in accompany with clinical manifestations and a history of the disease