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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 the Test is Performed

The health care provider cleans 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.

How to Prepare for the Test

No special preparation is necessary for this test.

How the Test will Feel

You may feel a brief sting as the needle is inserted just below the skin.

Why the Test is Performed

This test is used to determine if you have been exposed to the fungus that causes histoplasmosis.

Normal Results

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.

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 It has been replaced by a variety of blood and urine tests.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 (histoplasmosis). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 265.

Iwen PC. Mycotic diseases. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 61.

Update Date 9/10/2015

Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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