Immunodiagnosis of blastomycosis.

The diagnosis of blastomycosis has long been a challenge for the clinician. Primarily a pulmonary disease, blastomycosis is difficult to differentiate from other respiratory infections by clinical symptoms alone. Substantial improvement in the diagnosis of blastomycosis can be attributed to the availability of the purified A antigen of Blastomyces dermatitidis and its homologous antibody and the incorporation of these reagents into diagnostic tests. Reliable procedures for accurately and rapidly immunodiagnosing blastomycosis are available. These methods comprise enzyme immunoassay and immunodiffusion tests for detecting diagnostic serum antibody by B dermatitidis, the exoantigen test for identifying mycelial-form cultures of the etiologic agent, and the fluorescent antibody technique for detecting and identifying yeast-form cells in culture or in tissue. These tests, used alone or in combination, can in many cases provide an early and rapid definitive diagnosis of blastomycosis.