Tuberculosis Home > Latent Tuberculosis

Latent tuberculosis is a condition in which the body is able to fight the tuberculosis bacteria and stop them from growing. The bacteria then become inactive but remain alive in the body. Most people who have this form of tuberculosis never go on to develop active tuberculosis.

What Is Latent Tuberculosis?

Tuberculosis (TB) is a disease caused by a bacterium called Mycobacterium tuberculosis. The bacterium usually attacks the lungs. However, TB bacteria can attack any part of the body such as the kidneys, spine, and brain.
TB is spread through the air from one person to another. The bacteria are put into the air when a person with active tuberculosis of the lungs or throat coughs or sneezes. People nearby may breathe in these bacteria and become infected.
In most people who breathe in the tuberculosis bacteria and become infected, the body is able to fight the bacteria to stop them from growing. The bacteria become inactive, but they remain alive in the body and can become active later. This is called latent tuberculosis.

Characteristics of Latent Tuberculosis

People with latent tuberculosis:
  • Have no symptoms of tuberculosis
  • Don't feel sick
  • Can't spread tuberculosis to others
  • Usually have a positive tuberculosis skin test reaction (PPD test)
  • In some cases, can develop active tuberculosis if they do not receive treatment for latent tuberculosis.
People who have latent tuberculosis need to know the active tuberculosis symptoms. If they develop symptoms of active TB, they should see a doctor right away.

Progression of the Disease

Many people who have latent tuberculosis never develop active tuberculosis. In these people, the tuberculosis bacteria remain inactive for a lifetime without causing disease. In other people, however, especially people who have weak immune systems, the bacteria become active and cause active tuberculosis.
People with active tuberculosis can be treated and cured if they seek medical help. Also, people with latent tuberculosis can take medicine so that they will not develop active tuberculosis at all.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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