A diagnosis of
latent tuberculosis (LTB), also called
latent tuberculosis infection (LTBI) means a patient is infected with
Mycobacterium tuberculosis, but the patient does not have active
tuberculosis. Active tuberculosis can be contagious while latent tuberculosis is not, and it is therefore not possible to get TB from someone with latent tuberculosis. The main risk is that approximately 10% of these patients (5% in the first two years after infection and 0.1% per year thereafter) will go on to develop active tuberculosis. This is particularly true, and there is added risk, in particular situations such as
medication that suppresses the immune system or advancing age.