Estimates of C. immitis infection by skin test reactivity in an endemic community

Abstract

This report is a comparison of two delayed hypersensitivity skin test reagents, coccidioidin and Spherulin®, available for detection of prior infection by Coccidioides immitis. Coccidioidin proved to be a somewhat more sensitive reagent (33.4% positive, vs 29.6% for Spherulin®). This difference persisted in the subjects when grouped by age, sex, exposure history, or history of coccidioidomycosis. Skin test reactivity to both reagents declined with age. Independent of exposure history coccidiodin detected 7.3% of the subjects who were not detected by Spherulin®; Spherulin® detected prior infection in only 3.5% of the subjects not detected by coccidioidin. These results differ from those of previously reported studies.