Tuberculosis is caused by the invasion of Mycobacterium tuberculosis, the causative agent of tuberculosis, which is transmitted through the air, mainly through the respiratory tract. However, not all patients with tuberculosis can transmit the bacillus from themselves to others, but only if they are able to eliminate the bacillus from their bodies. Therefore, only patients who have eliminated the bacillus from their bodies are likely to expel the bacillus into the air and transmit it to the surrounding population. Tuberculosis is transmitted by droplet infection and dust transmission. When coughing, sneezing or talking loudly, small sputum containing bacteria is ejected from the patient’s mouth, and this small sputum is called droplet. The droplets containing bacteria can stay in the air for a long time. At this time, if a healthy person is very close to the patient, it is possible to inhale the droplets containing bacteria into the lungs and be infected, this infection is called droplet infection. In addition, if the patient spits out the sputum containing bacteria on the ground, the sputum will dry and the bacillus will be attached to the dust, and when the wind is blowing or when the ground is cleaned, the dust containing bacteria will fly up. If you breathe it into your lungs, you may be infected, and this infection is called dust infection. Since these infections occur through the respiratory tract, they are collectively referred to as respiratory infections. Mycobacterium tuberculosis can also be transmitted through the digestive tract. Patients with Mycobacterium tuberculosis sputum may get Mycobacterium tuberculosis on leftover food or used dishes. These ways are called dietary transmission and contact transmission. In addition, you can also become infected with Mycobacterium tuberculosis by drinking milk that has not been sterilized by boiling.