What is the difference between latent TB infection and TB disease?

A Person with Latent TB Infection (LTBI):

  • Usually has a skin test or a blood test result indicating TB infection*
  • Usually has a normal chest x-ray
  • Has TB bacteria in their body that are alive but inactive
  • Has no symptoms
  • Does not feel sick
  • Cannot spread TB to others
  • Can take treatment for LTBI to reduce their risk of developing TB disease

A Person with Active TB Disease:

  • Usually has a skin test or a blood test result indicating TB infection*
  • Usually has an abnormal chest x-ray
  • Has TB bacteria in their body that are active (growing)
  • Usually feels sick and experiences symptoms
  • May spread TB to others
  • Needs treatment to cure the active TB disease

* - A positive tuberculin skin test (TST) or a positive blood test only shows that you have been infected with the TB bacteria. Neither test can tell if you have TB disease, only if the TB bacteria are in your body.

Last modified on 01/12/2015