An ancient bacterial disease still causes millions of cases yearly. Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, most often affecting the lungs but capable of involving almost any organ.

Airborne droplets spread the bacteria. Most infected people contain the organism as latent infection; a minority develop active disease with cough, fever, night sweats, and weight loss. Diagnosis uses sputum microscopy, molecular tests, culture, and imaging. Drug-resistant strains complicate therapy.

Standard treatment requires multiple antibiotics for many months. Directly observed therapy improves completion rates. Bacille Calmette-Guérin vaccination and infection-control measures reduce spread. Global control depends on case detection, treatment completion, and addressing social determinants such as overcrowding and malnutrition.

• Infectious disease caused by Mycobacterium tuberculosis
• Primarily pulmonary but can be disseminated
• Spread by airborne droplets
• Treated with prolonged multi-drug regimens