A person with active TB is contagious under what condition?

• A. Only after symptoms develop
• B. As soon as infected
• C. From the moment of exposure
• D. Never contagious

Answer: (A)

The key idea is that TB spreads via infectious droplets from coughing, so contagiousness is tied to an active, productive cough with sputum. When active TB symptoms have developed, especially a productive cough, the person is contagious because bacilli are being expelled in droplets. Before symptoms appear, there isn’t a cough with sputum to spread the bacteria, so transmission is unlikely. Among the options, “Only after symptoms develop” best captures this reality. The other statements don’t fit: being infected doesn’t automatically make someone contagious (latent infection isn’t infectious); contagiousness isn’t guaranteed from the moment of exposure ( exposure itself isn’t transmission); and saying “never contagious” is incorrect for active TB.