Not all tuberculosis patients are infectious, but only those who have what is medically known as bacillary excretion, commonly known as “open tuberculosis,” are infectious and are the source of tuberculosis infection. The main site of TB is the lungs. Patients with open tuberculosis can become infectious by coughing up sputum and expelling Mycobacterium tuberculosis, which can be spread by droplets through the respiratory route, causing others to become infected. Open tuberculosis is highly infectious, requires isolation, and is more difficult to treat. Patients with non-open tuberculosis do not excrete the bacillus, do not have infectious properties, and do not need to be isolated. Human infection with TB bacilli does not necessarily lead to disease onset, but may cause clinical morbidity and even other complications when the immunocompromised population, the elderly, or patients with other underlying diseases have reduced resistance or increased cell-mediated metaplasia, and require early treatment to avoid aggravation and increased difficulty in healing. Therefore, tuberculosis is contagious, especially open tuberculosis, and patients are advised to seek early medical treatment, early detection and early treatment to avoid delaying the disease, to have a scientific and regular diet, to supplement nutrition, to have a balanced intake, to insist on exercise, and to have BCG vaccination for newborns in a timely manner.