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Facts About...

Latent Tuberculosis Infection (LTBI)


What is it?

Latent tuberculosis infection (LTBI) is a dormant infection with TB. LTBI can occur when a person is in contact with the TB bacteria (germ). TB bacteria are in the air and are inhaled into the lungs. The body’s immune system fights the bacteria by building a wall to stop TB from spreading. The person is then considered to have latent tuberculosis infection or LTBI. People with LTBI do not feel sick and cannot spread the bacteria to others.

Some people with LTBI may then develop active TB disease. TB disease can happen because of a weakened immune system.

Symptoms of active TB disease of the lung can include cough, fever, night sweats, weight loss, loss of appetite and tiredness. See Facts About... Tuberculosis.

People with LTBI:

  • Have no symptoms of TB
  • May have a normal chest X-ray
  • Cannot spread the TB bacteria

How is it spread?

People with LTBI are not contagious and cannot spread TB. The TB bacteria are not growing. A person with LTBI that develops TB disease (active TB) of the lung or throat who coughs, sneezes, sings, or even speaks can send TB germs into the air.

TB germs can stay in the air for several hours, especially in enclosed spaces. Persons breathing in the air containing TB germs can inhale the bacteria.

TB is not easy to catch, it usually takes several hours of close contact with a person who has active TB disease to become infected.

What do I look for?

People with LTBI often do not know that they are infected.

Testing for LTBI is done with a tuberculosis skin test (TST) or sometimes with a blood test (IGRA). See Facts About... TB Skin Testing.

How is it treated?

LTBI can be treated with medication prescribed by your doctor/health care provider.

TB medications are available free of charge through the Health Department.

If taken properly, the medication can stop the bacteria from developing into active TB disease.

Screening and treatment for LTBI should be considered based on risks for prior TB exposure and risk factors for development of active TB.

How can I protect myself?

  • Discuss testing and risk factors for TB exposure with your health care provider.
  • If you are planning to travel to a country known to have high rates of TB it is important to have a TB skin test before and after your trip. Areas with high rates of TB include: Asia, Africa, India, the Middle East, Central and South America, and the Caribbean.
  • If your TB skin test is positive, contact your doctor/health care provider or Health Department.
  • Make sure that you take all the medication as prescribed by your doctor/health care provider.
  • Avoid smoking.
  • Cough or sneeze into your elbow and encourage others to do the same.
  • If you are ill, stay home and isolate yourself from others.

August 2016