Which disease is a chronic infection caused by Mycobacterium tuberculosis affecting the lungs?

• A. Emphysema
• B. Sinusitis
• C. URI
• D. Tuberculosis (TB)

Answer: (D)

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis that primarily involves the lungs. It spreads through airborne droplets and can exist as latent infection or progress to active disease. The bacteria trigger a granulomatous immune response, forming tubercles in the lung tissue and sometimes causing cavitation, which leads to a slow, persistent illness. Common signs include a long-lasting cough, chest pain, coughing up blood, fever, night sweats, and weight loss. Diagnosis combines sputum tests for the bacteria, skin testing or blood tests for TB infection, and chest imaging. Treatment requires a multi-drug regimen over several months to effectively cure and prevent resistance. The other conditions listed are noninfectious lung disease (emphysema) or infections of the sinuses or upper respiratory tract (sinusitis and URI).