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 latent TB infection.
People with latent TB infection:
- Have no symptoms
- Don’t feel sick
- Can’t spread it to others
- Usually have a positive skin test reaction
- Can develop active TB disease if they do not receive treatment for latent TB infection
Many people who have latent TB infection never develop active TB disease. In these people, the TB bacteria remain inactive for a lifetime without causing disease. But in other people, especially people who have weak immune systems, the bacteria become active and cause TB disease.