Tuberculosis is a contagious disease, an infectious disease of the whistle tract, which can be transmitted by droplets and has a high transmission rate, and 550 million people in China have been infected with the tuberculosis bacteria. However, only 5-10% of the infected people develop active TB disease during their lifetime. Even so, the TB epidemic in China is relatively serious, with about 4.5 million active TB patients nationwide and the number of TB cases accounting for about 14.3% of the world’s population, ranking second in the world. There are specific conditions for both infection and disease onset. In addition to genetic polymorphisms, the main thing is the cellular immune function of the individual, and the stronger the immune function, the less likely it is to develop. People with strong immune function may not be infected even if they are in close contact with patients with bacillary TB; conversely, patients with AIDS and diabetes, who have poor cellular immune function, may easily be infected with TB. Next is the lung mass and airway clearance, such as silicosis and COPD patients, who are more susceptible to TB. TB infection usually develops within six months of onset, and the longer the time, the lower the incidence.