Cat scratch disease skin test
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 available to diagnose cat scratch disease, such as antibody detection by the EIA test or bacteria detection by a PCR test.
The test site (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.
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.
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.
This test was once used to diagnose cat scratch disease, before Bartonella henselae, the bacteria that causes CSD, was identified.
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.
An area of inflammation larger than 5 millimeters may suggest that you have been infected with cat scratch disease recently or in the past.
Although this test has historical value, there are better tests available for diagnosing CSD. Also, the CSD antigen is not widely available and it carries the possible 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).
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.
Slater LN, Welch DF. Bartonella, including cat-scratch disease. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 235.
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