Definition of Coccidioidin skin test:

The coccidiodin skin test checks to see if you are infected with the fungus that causes coccidioidomycosis.

The spherulin test also looks for this fungus, but it may be a more sensitive test. That means it may pick up signs of the infection earlier or more accurately.

How the test is performed:

Coccidiodin and spherulin are substances called antigens that are specifically associated with the fungus that causes coccidioidomycosis.

One of these substances is injected just below the skin's surface, usually in the forearm. Your health care provider will look at your arm 24 hours and 48 hours after the test. If your body has antibodies to the coccidiomycosis fungus, your body will react to the antigen. The area of the shot will become red.

How to prepare for the test:

No special preparation is 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:

Doctors once ordered this test if a patient had signs or symptoms of coccidioidomycosis, or had been exposed to the fungus that causes the disease.

However, this skin test is no longer used to diagnosis patients. It is not specific and is mostly used in research to better understand the causes, spread, and control of the disease among a specific group of people.