Evaluation of enzyme immunoassay as a rapid screening test for histoplasmosis and blastomycosis

This study evaluates the usefulness of enzyme immunoassay (EIA) as a screening test for serum antibodies to Histoplasma capsulatum and Blastomycoses dermatitidis and compares the results using this assay with those using complement fixation (CF), immunodiffusion (ID), and radioimmunoassay (RIA), in 12 patients with active histoplasmosis, 12 with active blastomycosis, 28 with other acute or chronic lung diseases and 25 healthy blood donors from an endemic area; EIA was as sensitive as RIA and more sensitive than CF and ID in the 24 patients with active fungal infections. The specificity of EIA was equal to that of the other serologic tests. We conclude that EIA is a useful screening test for serum antibodies to H. capsulatum and B. dermatitidis that avoids some of the problems associated with other sensitive assays such as RIA. A negative EIA result is evidence against invasive histoplasmosis or blastomycosis and suggests an alternative diagnosis.