Prospective Evaluation of Enzyme-Linked Immunosorbent Assay and Immunoblot Methods for the Diagnosis of Endemic Strongyloides Stercoralis Infection

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  • Department of Zoology, The University of the West Indies, Wellcome Research Centre for Parasitic Infections, Department of Biology, Imperial College, Liverpool School of Tropical Medicine, Mona, Kingston, Jamaica

Recently described enzyme-linked immunosorbent assay (ELISA) and immunoblot methods for the detection of serum IgG against Strongyloides stercoralis larval antigens were prospectively evaluated for the diagnosis of endemic strongyloidiasis. A modification of the ELISA involved preincubation of sera with Onchocerca gutturosa phosphate-buffered saline-soluble extract to remove cross-reactivity with other helminths. The sensitivity of the ELISA increased from 80% to 85% following preincubation. Similarly, there was an increase in specificity from 94% to 97%. The IgG recognition of 41-, 31-, and 28-kD filariform larval components showed sensitivities of 100%, 85%, and 65%, respectively. The specificities of recognition of these proteins were 94%, 89%, and 75%, respectively. Both the ELISA following incubation of sera with O. gutturosa extract and serum IgG reactivity to a 41-kD larval component using immunoblotting are sensitive and specific techniques for diagnosing endemic strongyloidiasis.