However, latent TB bacteria can 'wake up' and become active in the future, making you ill. This can happen many years after you first breathe in TB bacteria. Latent TB bacteria are more likely to wake up if you experience lifestyle stresses or other illnesses that weaken your immune system.

What are the chances of latent TB becoming active?

The lifetime risk of reactivation TB for a person with documented LTBI is estimated to be 5–10%, with the majority developing TB disease within the first five years after initial infection. However, the risk is considerably higher in the presence of predisposing factors, such as HIV infection.

How long before TB becomes active?

How soon do symptoms appear? Most people infected with the germ that causes TB never develop TB disease. If TB disease does develop, it can occur two to three months after infection or years later.