CSD skin test
The CSD skin test determines whether or not a person has been infected with cat scratch disease. It is performed by injecting a CSD antigen under the skin with a needle. After 48 to 72 hours the site of injection is evaluated by a physician. If the test is positive the injection site will show evidence of a reaction.
Also known as: Cat scratch disease skin test
- Allergic reaction, including itching and hives (rare)
- Possible spread of viruses to patient
Definition
The CSD skin test was once used to help diagnose cat scratch disease.
The test is rarely used today and is not recommended. There are better methods, such as antibody detection by the EIA test, available to diagnose cat scratch disease.
How the test is performed
The test site (an area with hair, usually the forearm) is cleansed. An antigen related to the bacteria that cause cat scratch disease is injected just under the skin. After 48 - 72 hours, a health care provider will check the injection site to determine whether your body has reacted to the substance.
How to prepare for the test
There is no special preparation. People with dermatitis or other skin irritations should have the test performed on an area of skin where there is no irritation.
How the test will feel
When the antigen is injected, you may feel a stinging sensation where the needle is inserted. After the reaction begins, the area may itch or burn.
Why the test is performed
This test was once used to diagnose cat scratch disease, before Bartonella henselae, the bacteria that causes CSD, was identified.
Normal Values
Inflammation around the injection site should be less than 5 millimeters wide.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
An are of inflammation larger than 5 millimeters may suggest that you have been infected with cat scratch disease recently or in the past.
What the risks are
Special considerations
Although this test has historical value, there are better tests available for the diagnosis of CSD. In addition, the CSD antigen is not widely available and carries the potential risk of transmitting other harmful substances such as viruses.
This skin test is not widely available, is not standardized, and is NOT approved by the Food and Drug Administration (FDA).
References
Hoesley CJ, Relman DA. Disease caused by Bartonella species. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 336.See also:
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Special Topic
Antigen
An antigen is any substance that causes your immune system to produce against it. An antigen may be a foreign substance from the environment such as chemicals, bacteria, viruses, or pollen. An antigen may also be formed within the body, as with bacterial or tissue cells.
- Review date:
- May 30, 2009
- Reviewed by:
- David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; 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. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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