How is pulmonary tuberculosis transmitted? First, we need to know the pathogen of pulmonary tuberculosis, which is the tuberculosis bacillus. Tuberculosis bacillus is a type of bacterium that can live in our surrounding environment. Pulmonary tuberculosis also needs a source of infection, that is, a patient carrying the tuberculosis bacillus. The most common source of tuberculosis infection is usually patients with secondary pulmonary tuberculosis. Then, its mode of transmission mainly includes coughing, sneezing, laughing, and talking loudly, which can release the tuberculosis bacilli from the patient into the air, spreading them through droplets. Droplet transmission is the most important route for the spread of pulmonary tuberculosis. Additionally, pulmonary tuberculosis can also be transmitted through other routes such as the gastrointestinal tract or the skin, although these methods of transmission are less common.