A tuberculin test to determine whether a person has had previous contact with the tuberculosis bacillus.
A test for allergy, in which a substance is applied to the skin to see if a reaction occurs.
Tests in which an antigen, an allergy causing substance, is applied to the skin in order to observe the response of the person being tested. Skin tests are commonly performed to determine whether a person is capable of having an immune response, to identify whether a person has allergic reactions to specific allergens, and to determine whether a person has been exposed to or is immune to an infectious disease. Common skin tests include the patch test, the scratch test, and intradermal tests, in which a small amount of antigen is injected under the skin. In intradermal tests, if redness and swelling develop within 20 minutes, the skin test result is positive. Skin tests are useful in detecting allergies to insect bites, penicillin, and foods; respiratory allergies; and infectious diseases, such as tuberculosis.
Any test in which a suspected allergen is applied to the skin. A variety of tests have been developed to detect the presence of IgE antibodies to specific substances. Cutaneous tests include the scratch test, in which a tiny amount of dilute allergen solution is placed on a 1-cm skin scratch created by a sterile needle, and the prick or puncture test, in which a drop of allergen solution is placed on the skin and a needle prick is made in the center of the drop. These tests are performed on the back or arm and are unlikely to produce systemic anaphylaxis. For an intradermal test, approx. .01 ml of dilute solution is injected into the skin on the arm using a tuberculin syringe with a 25- to a 27-gauge needle; the patient must be monitored for an anaphylactic reaction.
Methods for assessing the body’s reaction to different substances, either by applying them to the skin, typically via patches, or by injecting a small amount of the substance under the skin.
Patch tests are commonly employed to diagnose contact allergic dermatitis, as exposure to allergens will lead to areas of red or blistered skin. Injections, on the other hand, are used to identify substances responsible for allergic conditions like asthma. They can also be used to assess immunity to specific infectious diseases, as seen in the tuberculin test for tuberculosis.