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Test ID: COXIC    
Coccidioides Antibody with Reflex, Spinal Fluid

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

An aid for the diagnosis of meningeal infection with Coccidioides immits/posadasii

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

Coccidioidomycosis (Valley fever, San Joaquin Valley fever, Desert Rheumatism) is a caused by the dimorphic fungus Coccidioides immitis/posadasi, which is found in the southwestern United States and in Central and South America. It is acquired by inhalation of airborne Coccidioides arthroconidia. The majority of infections are subclinical. Among symptomatic patients, the majority will present acute flulike, pulmonary symptoms approximately 7 to 28 days post exposure, which may include chest pain, cough, fever, malaise, and lymphadenopathy.(1) A rash often develops within a couple of days, followed by erythema nodosum or multiforme with accompanying arthralgia. A pulmonary coin lesion or nodule may develop months following infection and may be a source of infection if the patient becomes immunosuppressed in the future. Coccidioidomycosis may disseminate beyond the lungs to involve multiple organs including the meninges. Individuals at greater risk for dissemination include African-Americans, patients of Filipino descent, pregnant women and immunocompromised patients.(2)

 

Serologic testing for coccidioidomycosis should be considered when patients exhibit symptoms of pulmonary or meningeal infection and have lived or traveled in areas where Coccidioides 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.

Negative

Interpretation Provides information to assist in interpretation of the test results

A positive result is presumptive evidence that the patient has a meningeal infection with Coccidioides immits/posadasii. This specimen will be tested by complement fixation and immunodiffusion for confirmation.

 

A negative result indicates the absence of antibodies to Coccidioides immitis/posadasii and is presumptive evidence that the patient has not been previously exposed to and is not infected with Coccidioides. However, a negative result does not preclude the diagnosis of coccidioidomycosis as the specimen may have been drawn before antibodies levels were detectable due to early acute infection or immunosuppression. If infection is suspected, another specimen should be drawn in 7 to 14 days and retested to look for seroconversion.

 

This test is designed for the qualitative detection of both IgM- and IgG-class antibodies against antigens from Coccidioides. The report will not indicate which class of antibody is present.

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

Results must be interpreted in the context of patient presentation. The presence of antibodies in cerebrospinal fluid (CSF) may be due to contamination of the specimen following a traumatic lumbar puncture or nonspecific permeability through the blood-brain barrier. A negative result does not rule out infection as antibody levels may be below detectable levels at the time of CSF collection.

 

Rarely, cross-reactivity of the Coccidioides antibody, screen may occur in patients infected with other dimorphic fungal agents including Histoplasma and Blastomyces.

Supportive Data

Sixty-seven prospective cerebrospinal fluid (CSF) specimens were tested in a blinded fashion by the IMMY OMEGA Cocci Ab EIA kit and by complement fixation (CF)/immunodiffusion (ID), which are considered the gold standard method. An additional 18 CSF specimens, spiked positive sera near the assay limit of detection, were also analyzed. Specimens were considered positive by the OMEGA Cocci EIA if either 1 or both the TP-Ag or CF-Ag antigen wells were positive; both TP-Ag and CF-Ag results were required to be negative for the specimen to be considered negative. Similarly, either 1 or both the CF and immunodiffusion assays were required to be positive for the specimen to be considered positive by the gold standard method; both the CF and ID assays were required to be negative for the specimen to be considered negative. The results are summarized below:

 

Table 1. Comparison of the IMMY OMEGA Cocci EIA to CF/ID for Detection of Antibodies to Coccidioides

 

CF/ID

IMMY Cocci EIA

 

Positive

Negative

Total

Positive

20

0

20

Negative

0

65

0

 Total

20

65

85

 

Sensitivity: 100% (20/20); 95% Confidence Interval (CI): 81.0%-100%

Specificity: 100% (65/65); 95% CI: 93.3%-100%

Overall Percent Agreement: 100% (85/85); 95% CI: 94.8%-100%

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Thompson GR: Pulmonary coccidioidomycosis. Semin Respir Crit Care Med 2011;32(6):754-763

2. Ruddy BE, Mayer AP, Ko MG, et al: Coccidioidomycosis in African Americans. Mayo Clin Proc 2011;86(1):63-69