Only patients whose active phlegm contains tuberculosis bacteria are infectious. Many cases of tuberculosis are actually non-contagious. For example, extrapulmonary tuberculosis, such as lymph node tuberculosis, tuberculous pleurisy, and tuberculous meningitis, are not contagious. Pulmonary tuberculosis patients, whose phlegm contains tuberculosis bacteria, are contagious and need appropriate respiratory isolation and should begin anti-tuberculosis treatment as soon as possible. Through anti-tuberculosis treatment, contagious pulmonary tuberculosis can become non-contagious.