Test Catalog

Test Id : SCOC

Coccidioides Antibody, Complement Fixation and Immunodiffusion, Serum

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

Diagnosis of coccidioidomycosis using serum specimens

Method Name
A short description of the method used to perform the test

Complement Fixation (CF)


NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Coccidioides Ab, CompF/ImmDiff, S

Lists additional common names for a test, as an aid in searching

Coccidioides antibody, S

San Joaquin Valley fever

Valley Fever


Specimen Type
Describes the specimen type validated for testing


Ordering Guidance

This test is a confirmatory assay for positive screening tests (ie, enzyme immunoassay).


The recommended test to evaluate for possible Coccidioides infection is COXIS / Coccidioides Antibody Screen with Reflex, Serum.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1.8 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.


If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1.2 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
Frozen 14 days

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

Diagnosis of coccidioidomycosis using serum specimens

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 US, 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 a day or 2, 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.


IgG antibody is detected by the complement-fixation tests. Precipitating antibodies (IgM and IgG) are detected by immunodiffusion. They are rarely found in cerebrospinal fluid; however, their presence is associated with meningitis. Chronic coccidioidal pulmonary cavities are often accompanied by IgG and IgM precipitating antibodies.


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

Provides information to assist in interpretation of the test results

Complement Fixation:

Titer results of 1:2 or higher may suggest active disease; however, titers may persist for months after infection has resolved. Increasing complement fixation (CF) titer results in serial specimens are considered diagnostic of active disease.



The presence of IgM antibodies may be detectable within 2 weeks after the onset of symptoms; however, the antibody may be detected longer than 6 months after infection.


The presence of IgG antibodies parallels the CF antibodies and may suggest an active or a recent asymptomatic infection with Coccidioides immitis/posadasii; however, antibodies may persist after the infection has resolved.


An equivocal result (a band of nonidentity) cannot be interpreted as significant for a specific diagnosis. However, this may be an indication that a patient should be followed serologically.


Over 90% of primary symptomatic cases will be detected by combined immunodiffusion and CF testing.

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

Antibodies (both IgM and IgG) may be present after the infection has resolved.

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

Method Description
Describes how the test is performed and provides a method-specific reference

Complement Fixation:

Antibody to coccidioidin in the patient's serum is quantitated by complement fixation (CF). The CF test is a 2-stage test based on the ability of antigen-antibody complexes to bind complement (C'). In the first stage, antigen and antibody combine and fix C'. The second stage is an indicator system in which sheep erythrocytes, sensitized by rabbit anti-sheep red cell antibody (hemolysin), are used to demonstrate the presence of unfixed C'. If the patient's serum contains C'-fixing antibody that reacts with the specific antigen (a positive reaction), C' will be fixed and excess C' will not be available to react with and lyse the sensitized sheep erythrocytes. If no antigen-antibody reaction occurs (a negative reaction), C' will be available to lyse the sheep erythrocytes. The CF titer is determined by the greatest dilution of serum (antibody) in which the sheep erythrocytes are not lysed.(Kaufman L, Kovacs JA, Reiss E: Immunomycology. In: Rose NR, de Macario ED, Folds JD, Lane HC, Nakamura RM, eds. Manual of Clinical Laboratory Immunology. 5th ed. ASM Press; 1997:591-592; Pappagianis D, Zimmer BL: Serology of coccidioidomycosis. Clin Microbiol Rev. 1990;3:247-268; 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)



Immunodiffusion (ID) is a qualitative test employed for the detection of precipitating antibodies present in the serum. Soluble antigens of the fungus are placed in wells of an agarose gel filled Petri dish and the patient's serum and a control (positive) serum are placed in adjoining wells. If present, specific precipitate antibody will form precipitin lines between the wells. Their comparison to the control serum establishes the results. When performing the ID test, only precipitin bands of identity with the reference bands are significant.(Kaufman L, Kovacs JA, Reiss E: Immunomycology. In: Rose NR, Macario ED, Folds JD, Lane HC, Nakamura RM, eds. Manual of Clinical Laboratory Immunology. 5th ed. ASM Press; 1997:591-593; Pappagianis D, Zimmer BL: Serology of coccidioidomycosis. Clin Microbiol Rev. 1990 Jul;3(3):247-268. doi: 10.1128/CMR.3.3.247; 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)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

4 to 7 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

86635 x 3

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
SCOC Coccidioides Ab, CompF/ImmDiff, S 87435-4
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
8295 Coccidioides Ab, CompF, S 5096-3
21649 Coccidioides, IgG, ImmDiff, S 62459-3
21648 Coccidioides, IgM, ImmDiff, S 62458-5

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports