Which mechanism is described as an airborne transmission?

• A. Direct contact.
• B. Droplet nuclei are disseminated in air.
• C. Vector-borne mechanical transmission.
• D. Waterborne spread.

Answer: (B)

Airborne transmission involves tiny particles, called droplet nuclei, that become suspended in the air and can be inhaled by people who are not in direct contact with the source. These small particles (often <5 micrometers) can riding air currents and travel farther than close-range droplets, allowing infection over some distance. This contrasts with direct contact transmission, which requires physical touch or exchange of secretions; vector-borne transmission, which uses an intermediary insect or animal; and waterborne spread, which occurs through contaminated water. Diseases like tuberculosis and measles spread via these aerosolized particles, making airborne precautions crucial in settings with such pathogens.