Tuberculosis (TB) is caused by a bacteria called Mycobacterium tuberculosis and is spread through the air from one person to another. This bacterium usually attacks the lungs; however it can attack any part of the body such as the kidney, spine, and brain. Not everyone infected with the TB bacteria becomes sick (referred to as latent TB infection, or LTBI).
Two kinds of tests are used to determine if a person has been infected with TB bacteria: the tuberculin skin test (TST) and TB blood tests.
TB Skin Test
HCHD offers the TST, which is also sometimes called the Mantoux tuberculin skin test.
All TB skin testing is done by appointment only. Individuals must return to the Health Department within 48 to 72 hours after the test to have the result read and recorded. Please be aware that holiday schedules can alter the days that testing can be performed. Call 419-599-5545 to schedule an appointment.
The test is performed by injecting a small amount of fluid (called tuberculin) into the skin on the lower part of the arm.
A person given the tuberculin skin test must return within 48 to 72 hours to have a public health nurse look for a reaction on the arm.
The public health nurse will look for a raised, hard area or swelling, and if present, measure its size using a ruler. Redness by itself is not considered part of the reaction
Understanding Test Results
A positive skin test means that a person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or active TB disease. People who have received the bacille Calmette-Guerin (BCG) TB vaccine may cause a person to have a false-positive reaction. TB blood tests are the preferred test for people who have received the BCG vaccine.
A negative skin test means the person’s body did not react to the test, and that latent TB or active TB disease is not likely.
