Elisa-based coproantigen in human strongyloidiaisis: a diagnostic method correlating with worm burden

ABSTRACT

In order to overcome the false negative diagnosis of strongyloidiasis in the absence of rhabditiform larvae in stools, an ELISA-based Strongyloides stercoralis-spicific coproantigen detection assay in stools of infected patients was evaluated. In a sandwich ELISA, a rabbit hyperimmune serum against S. ster-coralis ES [excretory/secretory] adult antigen succeeded in capturing S. ster-coralis coproantigen from infected patients and did not react with copro-antigens prepared from the stool samples of patients infected with Schistosoma mansoni, Fasciola gigantica and Capillaria philippenensis. Coproantigen was able to detect anti-S. stercoralis IgG antibodies in sera of infected patients at the same OD level as produced with S. stercoralis E/S worm antigen using an indirect ELISA did not cross-react with sera from patients with S. mansoni, F. gigantica and C. philippenensis. S. stercoralis coproantigen detection proved a sensitive, simple, reliable and inexpensive ELISA-based, and an alternative to coproscopical methods in copropositive [with larvae in stool] and copro-negative [without larvae in stool] stool samples. Fecal ELISA showed a positive relationship between copro-Ag and worm burdens, and considered a starting point for the development of species-specific copro-immunological diagnostic assays using monoclonal antibodies and dipstick technology