TB (latent) Infection

In most people who breathe in TB 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 TB (latent) infection


People with TB (latent) infection:

  • have no symptoms

  • do not feel sick

  • cannot spread TB to others

  • usually have a positive skin test reaction

  • can develop TB disease later in life if they do not receive preventive therapy (depending on the condition of the immune system )

Many people who have TB (latent) infection never develop TB disease. In these people, the TB bacteria remain inactive for a lifetime without causing disease. But in others, especially people who have a weak immune system, the bacteria become active and cause TB disease.


Copyright © 2010 Microbiology Department, Faculty of Medicine, Siriraj Hospital, Mahidol University. All rights reserved.