A new enzyme immunoassay specific for blastomycosis.

A highly specific enzyme immunoassay (EIA) was developed for the serodiagnosis of blastomycosis. Among the earliest sera available from eight active cases of blastomycosis, seven were reactive by EIA, three by immunodiffusion, and three by complement fixation. The one seronegative case was associated with acquired immunodeficiency syndrome (AIDS). No cross-reaction was observed with sera from 12 patients with active histoplasmosis or from five patients with active coccidioidomycosis or from 23 healthy persons. In contrast, all patients' sera cross-reacted in conventional EIAs based on commercial immunodiffusion antigens. The blastomycosis-specific EIA seems to offer sensitivity without compromising specificity. Rheumatoid factors, which could cause false-positive reactions, were controlled for.