Coccidioides immitis  Serology  CPT 86635

The immunodiffusion (ID) test is a qualitative test which detects precipitating antibodies in sera of individuals suspected of having coccidioidomycosis. Patient serum is placed in wells opposite a well containing serodiagnostic ID antigen derived from the mould form of C. immitis. Double diffusion of the specific antigen and antibody occurs, resulting in a line of precipitation. This test is 100% specific, thus only lines of identity are significant. Patients with positive serodiagnosis of coccidioidomycosis should be followed closely to determine if antifungal therapy is necessary. Patients may or may not experience disseminated disease when infected. Those with disseminated disease most likely require antifungal therapy.

The “F” band is found in the serum of approximately 80% of culturally confirmed cases. “F” and other bands (e.g. ID-TP, etc.) Together are found in approximately 5% of confirmed cases. The ID-COCCI test usually becomes positive within 1 month after a primary infection, but may be completely negative in up to 10% of symptomatic cases (NOTE: most of these negative cases are in the early primary stage of infection).

The greatest limitation of the test procedure is with specimens from patients with early, primary infections (first 1-6 weeks after infection). IgM antibodies usually predominate during this period and this macroglobulin (mw 800,000 daltons), diffuses very slowly in gels. The specificity of the serodiagnostic ID test is 100%. No other microorganism has been shown to elicit the specific diagnostic antibodies as seen in coccidioidomycosis (F antibody).

Specimen Requirements:
Volume: 0.5 ml serum and/or CSF may be tested.

Storage:
Specimens should remain frozen until testing is performed. Shipping: Specimens should be shipped on dry ice.

Testing Schedule:
Daily Monday-Thursday with reports 24 hours following date of setup.