Coccidioidomycosis, commonly known as Valley fever, is a fungal infection caused by the fungi Coccidioides immitis and Coccidioides posadasii. Accurate diagnosis of coccidioidomycosis is essential for appropriate patient management and treatment. The Complement Fixation Test (CFT) provides valuable insights into the immune response against Coccidioides antigens, aiding in the diagnosis and understanding of this fungal infection.

The CFT utilizes the interaction between antigens and antibodies, specifically activating the complement system. By measuring the patient's serum antibodies' ability to fix complement components when exposed to Coccidioides antigens, the CFT detects and quantifies specific immune responses.

The CFT plays a crucial role in differentiating coccidioidomycosis from other respiratory conditions and provides information on the severity and progression of the infection. Detection of specific antibodies against Coccidioides in patient serum indicates exposure to the fungus and suggests an ongoing or past infection.