Tuberculosis is a chronic infectious disease of the lungs caused by Mycobacterium tuberculosis invading the organism under certain conditions, of which sputum excretion is infectious tuberculosis. According to WHO estimates that there are currently 2 billion people infected with Mycobacterium tuberculosis worldwide, the number of active TB patients reaches 15 million, with 8-10 million new cases each year and 1.8 million deaths due to TB. 1, respiratory transmission Mycobacterium tuberculosis is present in the foci of tuberculosis in the lungs and bronchi, or in the lung space and sputum of secretions from the trachea. When a patient speaks loudly and coughs or sneezes, many tiny droplets are released, and the patient can release 3,500 droplets in one cough and even more when sneezing hard. If a susceptible person inhales such droplets with Mycobacterium tuberculosis, he or she can be infected. In addition, if a person with tuberculosis spits out sputum containing mycobacterium tuberculosis on the ground, after the sputum dries, the mycobacterium tuberculosis in the sputum mixes with dust and flies in the air, which can be inhaled by healthy people and cause infection. 2, food transmission The tableware and leftover food used by TB patients may be contaminated with Mycobacterium tuberculosis, such as sharing tableware with TB patients or eating leftover food from patients, or eating vegetables and drinking soup in a bowl, etc. Mycobacterium tuberculosis may also be introduced through diet. Drinking unpasteurized milk or dairy products can also infect bovine Mycobacterium tuberculosis. If you pour a sputum jar for a patient with bacillus excretion and accidentally get sputum on your hands, you may also get infected if you do not wash your hands carefully and eat food with your hands. Some women like to feed their babies by chewing food with their mouths, so if she is a TB excretor, the baby is likely to be infected. 3. Vertical transmission During pregnancy, the tuberculosis bacilli in the mother’s body can enter the fetus through the blood of the umbilical cord. Dr. Zhou pointed out that in addition to the above-mentioned modes of transmission, Mycobacterium tuberculosis can also be directly infected by wounds on the skin or mucous membranes.