However, when a person is infected by the TB bacillus, he will not usually immediately develop full-blown tuberculosis, and the bacterium may remain latent inside the body for a long period of time. Generally speaking, once infected, there is a roughly 10 % chance of a person developing an active case during the rest of his life. Of those who do develop TB, half do so within five years of infection.
但一個人受到結核菌感染通常不會立即發病，結核菌可長期潛伏在宿主體內，一般而言，受感染後一生中約有百分之十的發病機會；發病者有一半是在初感染後五年內發病；另一半則在五年後才發病。