Coccidioidin and spherulin are two different antigens and are both used to test for coccidioidomycosis. Spherulin may be a more sensitive test than coccidioidin.
How the test is performed: The test site (an area with hair, usually the forearm) is cleansed. The antigen is then injected just below the skin surface. The test is read at 24 hours and at 48 hours.
How to prepare for the test: There is no special preparation necessary.
How the test will feel: There will be a brief sting as a needle is inserted just below the skin's surface.
Why the test is performed: The test detects if the body's immune system responds to the fungus, indicating that the person has been exposed to this organism.
Normal Values: No reaction (inflammation) to the microorganism is normal.
What abnormal results mean: A positive reaction indicates there has been exposure to the microorganism. This test can be very helpful in diagnosing early infection, since the skin test can be positive 2-21 days after the onset of symptoms, even before�a�blood test�is positive. A significant number of patients will have anergy, or will not respond to this test even when they have the disease.
There can be false-positives, in that there can be positive results when the patient has been exposed to histoplasma fungus or blastomyces fungus, but not coccidioides. A positive result may also reflect exposure to coccidioides in the distant past, rather than�current infection.
Special considerations: Not applicable.
