Histoplasma skin test

Histoplasma skin test is a method to check if you have been exposed to a fungus called Histoplasma capsulatum. The fungus causes an infection called histoplasmosis.

How is the Test Performed?

The health care provider will clean an area of your skin, usually the forearm. An allergen is injected just below the cleaned skin surface. The injection site is checked at 24 hours and at 48 hours for signs of a reaction. Occasionally, the reaction may not appear until the fourth day.

Preparation for the Test

No special preparation is necessary for this test.

How the Test will Feel

There will be a brief sting as a needle is inserted just below the skin surface.

Why is the Test Performed?

This test is used to determine if a person has been exposed to the fungus that causes histoplasmosis.

Normal Results for Histoplasma skin test

No reaction (inflammation) at the site of the test is normal. The skin test can rarely make histoplasmosis antibody tests turn positive.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

A reaction means you have been exposed to Histoplasma capsulatum. It does not always mean you have an active infection.

Histoplasma skin test Risks

There is a slight risk of anaphylactic shock (a severe reaction).

Considerations

This test is rarely used today. It has been replaced by a variety of blood and urine tests.

References

Deepe GS Jr. Histoplasma capsulatum. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2009:chap 264.