Tuberculosis (TB) is a potentially serious infectious disease that mainly affects the lungs. TB is caused by the bacterium Mycobacterium tuberculosis and spreads through the air when an infected person coughs, sneezes, or speaks. Common symptoms include a persistent cough lasting three weeks or longer, chest pain, coughing up blood, fatigue, fever, night sweats, and unintentional weight loss. TB is treatable with a course of antibiotics, usually lasting 6-9 months.