Tuberculosis is a bacterial disease that primarily affects the lungs and has the potential to cause serious illness. It spreads through the air when an infected person coughs or sneezes. Although many people who become infected with tuberculosis do not experience symptoms, those who do may develop a persistent cough (sometimes with blood), night sweats, weight loss, and fever. While asymptomatic individuals may not require treatment, patients with active symptoms need a prolonged course of treatment that includes multiple antibiotics.