Before starting a new job, attending a new school or serving as a volunteer, you may be required to get immunizations, screenings or medical tests for your safety and the safety of others around you. One common screening is a tuberculin skin test to check for exposure to tuberculosis (TB) bacteria.
You may wonder, why is a TB test necessary?
The bacteria that cause TB — Mycobacterium tuberculosis — still affects a large part of the population. In 2016, 10.4 million people fell ill from TB and an estimated 1.8 million people died from TB, according to the World Health Organization.
“We test for TB to identify people at risk for developing active TB to prevent them from exposing other people,” says Dr. Joshua Minuto, an infectious disease specialist with Sharp Rees-Stealy Medical Group. “We can ensure that the exposed people get treated to protect the health of the public.”
TB bacteria are commonly found in the lungs, but can travel out of the lungs through the blood stream to other organs, such as the kidney, spine, heart or brain.
There are two TB conditions: latent and active.
Latent TB infection occurs when someone is exposed to TB and has TB organisms in the lungs, but does not develop active TB infection because their immune system controls the organisms. These people have no symptoms, but will have a positive TB skin test that shows they have been exposed. The treatment is usually an antibiotic regimen to reduce the risk of developing active TB.
Active TB infection occurs when TB is growing unchecked by the immune system. A person may experience symptoms such as a cough, blood in their sputum (saliva and mucus), weight loss and fatigue. Additional tests – such as a chest X-ray or sputum culture – may be performed to determine if the person has an active TB infection. The medications used for treatment and the duration depend on the extent of TB infection, the strength of the person’s immune system, and whether the TB organisms are resistant to any medications.
TB is spread through the air when a person with active TB infection coughs, sneezes or talks. To be exposed or infected, you have to be in very close contact with someone on a daily basis. An elevator ride or someone coughing at a restaurant who has active TB may be risky but isn't high-risk for TB transmission.
A TB test requires two visits to a doctor or clinic. During the first visit, you will receive a small shot (into your inner forearm) that contains TB protein antigens. A small bump typically forms at the site of the injection; this usually goes away in a few hours. You will return 48 to 72 hours after the injection to have your TB test read. A positive test may show swelling or a firm red bump at the site within two days, in which case additional testing may be needed. Sharp Rees-Stealy offers TB testing through its Occupational Health Program.
For the media: To speak with Dr. Minuto about tuberculosis or other infectious diseases, contact Senior Public Relations Specialist Erica Carlson at firstname.lastname@example.org.