What Is a TB Test and Why Do You Need One?


TB test

Tuberculosis (TB) is a disease caused by the tuberculosis bacteria, Mycobacterium tuberculosis. While the disease has been present for thousands of years, TB reached epidemic proportions in Europe and North America during the 18th and 19th centuries. Today, most cases of tuberculosis can be successfully treated with antibiotics and other drugs that kill the bacteria.

Symptoms of Tuberculosis

TB bacteria are spread through the air when an infected person coughs or speaks. When another person breathes in the bacteria, the bacteria may settle in the lungs and begin to multiply. TB can also cause infection in other parts of the body, such as the kidney, spine and brain.

Symptoms of an active TB infection in the throat or lungs include:

  • Severe cough lasting several weeks
  • Chest pain
  • Coughing up blood or mucus
  • Fever
  • Chills
  • Loss of appetite
  • Night sweats
  • Weakness or fatigue
  • Weight loss

Some people are infected with TB bacteria but show no symptoms. This is known as latent tuberculosis infection. While latent TB infection is not contagious, it may later lead to active disease.

About the TB Test

The purpose of a TB test is to determine whether a person has been infected with TB bacteria. Both the skin and the blood can be tested, but neither test will determine whether a person has a latent TB infection or TB disease. Other tests, such as a chest x-ray and a mucus sample, are necessary to diagnose active disease.

During a TB skin test, a clinician injects a small amount of liquid (called tuberculin) under the skin, usually on the forearm. A small, pale bump will form at the injection site. The person must then return in 48-72 hours so the clinician can assess for a reaction at the site of the injection. If the result of the TB skin test is positive, additional testing is needed to confirm infection and the need for treatment. Most people can receive a TB skin test, including infants, children and pregnant women.

TB testing generally is not necessary for those at low risk for TB infection. However, those who have TB symptoms, a weakened immune system, who live or work where TB is common, or who use illegal drugs are some examples of those who should be tested because they are at higher risk for infection and/or possible progression to TB disease. College students (particularly international students) may be required to receive a TB test prior to starting classes.

Get Tested for TB at RediClinic

The board-certified clinicians at RediClinic can conduct a TB skin test seven days a week. Our services are affordable, and our clinics are located inside select H-E-B grocery stores and Rite Aid Pharmacies. Make an online appointment to be seen at RediClinic.