Tuberculosis screening: Your questions answered

August 22, 2023

Tuberculosis (TB) is an infectious disease caused by exposure to bacteria called Mycobacterium tuberculosis, and it is estimated that nearly 25% of the world’s population has been infected with TB bacteria. While most people with a TB infection will not get sick, it’s important to know the symptoms, risk factors, and testing options available so you can be proactive about your health.


Whether you work in a high-risk setting for TB exposure, need to provide evidence of a negative TB test for travel or work, or simply want to know more about your risk, you may have questions. Here are answers to six common TB questions.

1. What are the symptoms of tuberculosis?


Not everyone with TB bacteria in their bodies will get sick or experience symptoms. The appearance of symptoms depends on whether the infection is latent or active.

You will only experience symptoms if you have an active TB infection, or TB disease. An active infection means the bacteria are actively multiplying and can be easily spread from person to person. Active TB disease is serious and potentially fatal if untreated. Symptoms of an active infection include:


  • A long-lasting cough that may bring up bloody mucus
  • Chest pains
  • Unexplained weight loss
  • Loss of appetite
  • Weakness or tiredness
  • Fever
  • Night sweats


If you suspect that you may have active TB or have any TB symptoms, you should see a healthcare provider for a complete medical evaluation.

If you have a latent TB infection, you will not experience symptoms and cannot spread your infection to others. This is because your immune system is preventing the bacteria from multiplying.


2. Can you get TB disease if you have latent TB?


Yes. If the immune system can no longer stop TB bacteria from multiplying, an untreated latent infection can become active TB disease.


In the U.S. alone, it’s estimated that 13 million people have latent TB infection, and 5%-10% of all people with an untreated latent infection are expected to develop active TB disease in their lifetime. If you have a medical condition that weakens your immune system, your risk can be much higher.


Since a latent infection does not have symptoms, it’s important to screen for exposure to TB bacteria. The Labcorp OnDemand Tuberculosis (TB) Blood Test can help determine if you have ever been exposed to TB bacteria, and can help you and your healthcare provider identify a latent infection and determine the best course of action to take before it progresses to an active infection.


3. Who is at risk for tuberculosis?


Some factors may increase your risk for developing a TB infection. Those most at risk include:


  • Living with someone with active TB disease
  • People infected with TB in the last two years through close contact with someone who has active TB disease
  • People who work in high-risk settings (e.g., healthcare settings, nursing homes, correctional facilities)
  • People who are from or frequently travel to regions with high rates of TB (e.g., Latin America, Africa, Asia and the Pacific Islands)
  • People with weakened immune systems (e.g., those living with HIV)
  • People with certain medical conditions (e.g., diabetes, severe kidney disease, substance abuse)


4. How often should I get tested for tuberculosis?


CDC recommends annual TB screening for healthcare workers who are at increased risk for TB exposure or who work in certain settings where transmission has occurred in the past (e.g., emergency departments). TB testing is not needed if you have a low risk of infection, but it is recommended if you are at increased risk or believe you have had recent TB exposure.


5. How can I get tested for tuberculosis?


Tuberculosis testing can be performed by skin test or blood test.
The skin test, also called a tuberculin skin test (TST), involves a trained healthcare worker injecting a small amount of a substance called purified protein derivative under your skin and inspecting the injection site two to three days later. If you’ve ever been exposed to TB bacteria, you may develop a red bump on your skin at the injection site.


Blood tests like Labcorp OnDemand’s Tuberculosis (TB) Blood Test are a more modern and convenient alternative to the skin test, and require only a single blood draw. This can mean getting your results sooner and saving you a trip to the doctor’s office to read your skin test results. Blood tests for TB also have fewer false-positive results when compared to skin tests, and results are not affected if you had a prior Bacille Calmette-Guerin (BCG) TB vaccination or had received TB vaccines in the past.


TB screening alone cannot diagnose latent or active TB. If your TB screening results are positive, you should contact your provider for next steps. Your healthcare provider may recommend additional tests and exams to confirm if you have an active TB disease or latent TB infection, and to determine the appropriate course of monitoring and/or treatment for you.


6. How is tuberculosis treated?

TB infection is typically treated with a combination of antibiotics over a period of several months to a year. The overall length of treatment depends on the medication prescribed and whether you have latent or active TB. It is important to follow the entire course of treatment as prescribed by your healthcare provider.

Screen for tuberculosis exposure with Labcorp OnDemand

Screen for exposure to TB with one simple blood test you can purchase yourself from Labcorp OnDemand. This blood test can also help you provide proof of a negative TB test for work, travel or school. As always, discuss your results with your healthcare provider to see if treatment or further testing is necessary.