Blastomycosis, caused by the dimorphic fungus Blastomyces dermatitidis, is a systemic fungal infection primarily affecting the lungs. The accurate diagnosis of blastomycosis is essential for effective patient management and treatment. Complement Fixation Test (CFT) serves as an immunological technique employed to detect and assess the immune response against Blastomyces antigens, aiding in the diagnosis and understanding of blastomycosis.

The CFT for Blastomyces provides qualitative and quantitative information about the patient's immune response to Blastomyces antigens. It aids in the diagnosis of blastomycosis, helping differentiate it from other respiratory infections. The presence of specific antibodies against Blastomyces in the patient's serum suggests exposure to the fungus and indicates a current or previous infection. The detection of complement fixation and the measurement of antibody titers can provide insights into the severity and progression of blastomycosis.