Active tuberculosis (TB) infection means that TB bacteria are present in a person’s body and are growing and causing symptoms. If the active TB infection is the lungs or other parts of the airway, it can be spread to other people. A latent TB infection means that TB bacteria are present in a person’s body, but his/her immune system is able to prevent the TB bacteria from growing. Individuals with latent TB infection are not able to spread TB to others.