A positive skin test indicates the presence of TB germs in your body. It means you likely have latent TB infection, but it doesn't necessarily mean you have active TB disease. A positive skin test, usually a tuberculin skin test (TST) or a blood test, is identified by a bump of a certain size at the injection site. To confirm active TB disease, your doctor will examine you and order a chest x-ray. If you have a positive skin test, your doctor may recommend further testing and treatment.
Examples of positive skin test results:
- TB skin test: A bump of 5mm or greater in diameter is considered positive for individuals with a higher risk of TB infection, like those with HIV, recent contact with someone who has TB, or those with weakened immune systems.
- Allergy skin test: A small area of swelling with surrounding redness is a sign of a positive allergy skin test.
