Tuberculosis (TB) is a disease caused by germs that spread through the air from person to person. While it commonly affects the lungs, it can also impact other areas like the brain, kidneys, or spine. This fact sheet provides basic details about TB transmission, symptoms, testing, and treatment.
To test for TB, a small amount of tuberculin is injected just beneath the skin on the inside of the forearm. After 48 to 72 hours, a healthcare worker examines the arm for swelling at the injection site. The size of the raised area determines whether the test is positive or negative.
This test checks if your immune system has responded to tuberculosis by producing antibodies. A positive result suggests you may have either a latent TB infection or active TB disease. Individuals who have received a TB vaccination might test positive even without an infection. A negative result means your body did not react to the test, but it doesn’t necessarily rule out an infection.
A blood sample is sent to a laboratory to determine whether specific immune system cells can detect tuberculosis. A positive outcome indicates the presence of either a latent TB infection or active TB disease. Further tests on the blood sample can help confirm active disease, while a negative result suggests you likely do not have a TB infection.
A chest X-ray can reveal irregular lung patches characteristic of active TB disease. If you have active TB disease in your lungs or throat, your healthcare provider may collect a sputum sample from your cough. Laboratory tests can identify the TB bacteria in the sputum, though results may take time. Drug-resistant forms of the bacteria can also be detected through these tests, guiding treatment decisions.
Latent TB infections, especially in individuals with HIV/AIDS or other risk factors, may require drug treatment, typically lasting three to four months. Active TB disease may necessitate treatment for four, six, or nine months.
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