Only persons with active TB disease (i.e. those who also show signs and symptoms of the disease) can spread TB to others. People with latent TB infection (i.e. people who have the TB bacteria but do not show any symptoms) cannot spread TB bacteria to others. A person exposed to someone with active TB disease, may become infected with the TB bacteria, but would not be able to spread the infection unless he or she starts showing symptoms of the disease. People who have latent TB infection can, however, be treated to prevent them from developing active TB.