Serologic studies in coccidioidomycosis

Serologic tests are valuable in the management of patients with suspected or confirmed coccidioidomycosis. Qualitative tests (immunodiffusion, enzyme immunoassay, or latex particle agglutination) permit detection in the serum of the major antibody responses-coccidioidal IgM in early coccidioidomycosis, and complement fixing (CF) IgG, which appears later and is more persistent. Quantitation of the level (titer) of coccidioidal IgG is useful in prognosis and diagnosis. The preferable antigen for these tests is coccidioidin from the hyphal phase of Coccidioides immitis. When coccidioidal disease has disseminated to an extrapulmonary site, the corresponding fluid-cerebrospinal, synovial, peritoneal (as well as pleural)-can be tested for coccidioidal antibody provided that the serum is known to be positive. Some immunocompromised patients may have a limited humoral responsiveness; therefore, it will be important to develop a practical method for the detection of coccidioidal antigen.