Test Catalog

Test ID: CCOC    
Coccidioides Antibody, Complement Fixation and Immunodiffusion, Spinal Fluid

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing coccidioidomycosis in spinal fluid

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Coccidioidomycosis (Valley fever, San Joaquin Valley fever) is a fungal infection found in the southwestern United States, Central America, and South America. It is acquired by inhalation of arthroconidia of Coccidioides immitis/posadasii. Usually, it is a mild, self-limiting pulmonary infection. Less commonly, chronic pneumonia may occur,  progressing to fibronodular cavitary disease. A rash often develops within 1 to 2 days, followed by erythema nodosum or multiforme and accompanying arthralgias. About 2 weeks after exposure, symptomatic patients develop fever, cough, malaise, and anorexia; chest pain is often severe. Coccidioidomycosis may disseminate beyond the lungs to involve multiple organs, including the meninges.


Serologic testing for coccidioidomycosis should be considered when patients exhibit symptoms of meningeal infection and have lived in or traveled to areas where Coccidioides immitis/posadasii is endemic. Any history of exposure to the organism or travel cannot be overemphasized when coccidioidomycosis serologic tests are being considered.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.



If positive, results are titered.




Results are reported as positive, negative, or equivocal.

Interpretation Provides information to assist in interpretation of the test results

Complement Fixation:

IgG antibody is detected by complement fixation (CF) testing. Any CF titer in cerebrospinal fluid (CSF) should be considered significant. A positive complement fixation test in un-concentrated CSF is diagnostic of meningitis.



IgM and IgG precipitins are rarely found in CSF. However, when present, they are diagnostic of meningitis (100% specific). Since the immunodiffusion test is 100% specific, it is helpful in interpreting CF results.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

While complement fixation (CF) titers may be present in serum months after the infection has resolved, any CF titer in spinal fluid should be considered significant.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Larone D, Mitchell T, Walsh T: Histoplasma, blastomyces, coccidioides, and other dimorphic fungi causing systemic mycoses. In: Murray PR, Baron EJ, Pfaller MA, et al, eds. Manual of Clinical Microbiology. 7th ed. ASM Press, 1999:1260-1261

2. Ramanan P, Wengenack NL, Theel ES: Laboratory diagnosis for fungal infections. A review of current and future diagnostic assays. Clin Chest Med. 2017 Sep;38(3):535-554. doi: 10.1016/j.ccm.2017.04.013

Special Instructions Library of PDFs including pertinent information and forms related to the test