Norm of Coccidioidomycosis Skin Test
Negative or no skin reaction.
Positive of Coccidioidomycosis Skin Test
Skin induration >5 mm in diameter indicates exposure to Coccidioides but gives no indication of duration. Associated with hypercalcemia.
Usage of Coccidioidomycosis Skin Test
Determine the exposure to fungal infections affecting the pulmonary system.
Description of Coccidioidomycosis Skin Test
Coccidioides immitis is a fungus found in the soil of dry climates of the southwest United States and Latin America. Spores in the dust are inhaled, causing respiratory infection that is mild and asymptomatic, or may cause acute to chronic pulmonary cavities and septic shock. A rare 1% of infected individuals develop disseminated disease or infection that is fatal. The course of the disease includes fever, malaise, and respiratory complaints, which become self-limiting as the client develops antibodies. In the disseminated form, the skin, bones, internal organs, and meninges are infected. This test is performed by injection of a Coccidioides antigen sample and observation for signs of an antibody reaction.
Professional Considerations of Coccidioidomycosis Skin Test
Consent form NOT required.
- Obtain an alcohol wipe, a syringe, a subcutaneous needle, and a Coccidioides antigen sample.
- Cleanse the volar aspect of the lower arm with an alcohol wipe and allow it to dry.
- Inject 0.1 mL of 1:100 dilution of coccidioidin or spherulin (which is more sensitive) subcutaneously.
- Circle the injection site with a pen or marker.
- Read the skin test 24 and 48 hours after the injection.
Client and Family Teaching
- The injection causes a stinging sensation.
- Do not wash off the marking until the test is read. Return in 24–48 hours to have the test site read.
Factors That Affect Results
- Low dilution of the antigen preparation (that is, 1:10) may produce a cross-reaction, indicating other fungal diseases.
- The skin test may be negative in the severe, disseminated form of the disease.
- Cross-reactions occur in clients with histoplasmosis.
- The advantage of skin testing is that results are available in approximately 24–48 hours.
- The main disadvantage is the time needed to develop antibodies.
- Clients with facial lesions are more likely to have meningitis.
- Fluconazole and itraconazole are effective therapies for coccidiomycosis.
- Clients who are immunosuppressed, male, Filipino, pregnant, blood types A/B and B, and elderly appear to be at an increased risk for coccidiomycosis.