Skin test antigens for immediate hypersensitivity prepared from infective larvae of Strongyloides stercoralis

More rapid and simplified diagnostic procedures are needed for the diagnosis of strongyloidiasis. One approach is the use of an immediate hypersensitivity skin test that would reliably identify infected people. Accordingly, somatic and excretion/secretion (E/S) antigens were prepared from filariform larvae of Strongyloides stercoralis and were treated to remove possible adventitious agents. By use of a quantitative method for measurement of skin reactions, several preparations of the 2 antigens were tested in uninfected controls and in various groups of patients. Doses of 0.35 microg of E/S and 4 microg of somatic antigens elicited positive skin tests in 82-100% of infected people, depending on clinical status. A lower frequency of positive skin tests was found in strongyloidiasis patients also infected with human T-cell lymphotropic virus type 1. Cross-reactions, especially to somatic antigens, were frequently found in patients with filarial infections. Despite these limitations and the need for further study of specificity, these results provide a basis for future development of a diagnostic skin test antigen for strongyloidiasis.