Latent TB is very different from active TB. Latent TB is not contagious and is not dangerous to others.
In 2004, I was diagnosed of latent TB and was cleared of active TB. I do not know how long I have had latent TB. It could be 10 years or 30 years. In 2004, my doctor recommended me to have my latent TB treated. But I refused, because the medicine has side effects to my liver and takes too long. Latent TB could only be brought active when one's immune system is severely comprised, for instance, when Remecade is administered. My father has latent TB all his life. He is in his 70s.