TB infection (latent TB)

A person can have TB bacteria in their body and never develop symptoms. In most people, the immune system can contain bacteria so that they do not replicate and cause disease. In this case, a person will have a TB infection but not active disease.

Doctors refer to this as latent TB. A person may never experience symptoms and be unaware that they have the infection. There is also no risk of passing on a latent infection to another person. However, a person with latent TB still requires treatment.

TB disease (active TB)

The body may be unable to contain TB bacteria. This is more common when the immune system is weakened due to illness or the use of certain medications.

When this happens, the bacteria can replicate and cause symptoms, resulting in active TB. People with active TB can spread the infection.