Latent TB infection is best described by which statement?

• A. No symptoms, not contagious
• B. Active coughing and fever
• C. Blood in sputum
• D. Weight loss

Answer: (C)

Latent TB infection is a dormant presence of Mycobacterium tuberculosis in the body, so there are no symptoms and the person is not contagious. This contrasts with active TB, where coughing, fever, night sweats, weight loss, and sometimes coughing up blood indicate contagious disease. Diagnosis of latent TB relies on a positive TB test or IGRA, with a normal chest X-ray and negative sputum tests, and treatment aims to prevent progression to active TB. Among the statements, the one describing no symptoms and not being contagious best fits latent TB, since blood in sputum and other active-disease signs point to active TB rather than latent infection.