1, respiratory transmission Patients with bacteriophageal tuberculosis (Mycobacterium tuberculosis is detected in sputum) are the main source of transmission of tuberculosis (only patients with tuberculosis nuclei in the lungs, trachea and larynx are transmitted). When a patient coughs, sneezes or laughs loudly, droplet nuclei containing Mycobacterium tuberculosis are discharged directly from the respiratory tract and are inhaled by healthy people to form tuberculosis infection, which is the main way of transmission of tuberculosis. A patient with bacillary tuberculosis, especially a patient with a positive direct sputum smear test, can emit about 3,500 particles containing Mycobacterium tuberculosis in a single cough, and very few bacillary particles are emitted during normal exhalation, while about 600 to 700 particles are emitted in a minute of loud talking and up to 1 million particles are dispersed into the air in a single sneeze. It is clear that the risk of infection is quite serious when coughing and sneezing in patients with positive tuberculosis. If the room is frequently opened for ventilation, the chance of infection can be greatly reduced. Patients with active tuberculosis, who generally have a cough, should routinely undergo X-ray chest radiography and sputum examination whenever they cough for more than two weeks to detect tuberculosis patients early and reduce the spread of tuberculosis. To strengthen patient education, use a handkerchief or mask as a cover when coughing or sneezing to avoid spreading bacteria and infecting others. 2. Gastrointestinal transmission The secondary way of infection is to enter the body through the gastrointestinal tract. Drinking unsterilized cow’s milk with Mycobacterium tuberculosis of bovine type may cause intestinal infection. A small amount of weakly virulent Mycobacterium tuberculosis can be killed by the body’s immune defense mechanism, but only when attacked by a large number of virulent Mycobacterium tuberculosis and the body’s immunity is insufficient does it cause disease.