Whether a patient with tuberculosis is infectious or not is mainly based on the sputum test, and a positive sputum test is infectious. Sputum examination includes sputum culture and sputum smear. A positive sputum smear for Mycobacterium antacidum or a positive sputum culture for Mycobacterium tuberculosis is sputum positive, and a positive sputum test is infectious. TB patients can spread microdroplets of Mycobacterium tuberculosis in the air by coughing, sneezing, talking, singing, etc., and others can be infected after inhaling them. Therefore, you should keep a certain distance from TB patients when you come in contact with them, and you can also block the transmission by wearing a mask. TB patients should also cover their mouths and noses when they cough or sneeze to avoid infecting others. TB patients should avoid going to places where people gather, and if they must go, they should wear a mask to avoid spreading the virus.