Which mechanism best describes how TB spreads?

• A. Droplet nuclei from coughing, sneezing, etc.
• B. Airborne spores
• C. Contaminated water
• D. Blood contact

Answer: (A)

Tuberculosis spreads through airborne transmission of the bacteria when a person with active pulmonary TB coughs, sneezes, talks, or sings. These actions release tiny respiratory particles that become droplet nuclei—small enough to stay suspended in the air for long periods. People nearby can inhale these nuclei and become infected, especially in enclosed, poorly ventilated spaces. This is why TB control focuses on proper ventilation and protective equipment like fit-tested N95 respirators for health care workers and negative-pressure rooms for patients.

Other options don’t fit because they describe transmission routes for different types of agents. Airborne spores would imply a fungus that releases spores; TB is caused by a bacterium and doesn’t spread via spores. Contaminated water transmits diseases such as cholera or typhoid fever, not TB. Blood contact transmits bloodborne pathogens (like HIV or hepatitis), not TB, which is primarily spread through the air breathed in from an infected person.