Question

Which of the following is NOT an example of direct transmission in communicable diseases?

• A. Transplacental (vertical)
• B. Soil
• C. Respiratory
• D. STD

Hint:

Airborne respiratory spread is classed as indirect transmission.

Answer 1

The Correct Option is C

Step 1: Sort each option into direct versus indirect transmission. Direct transmission means the agent passes from source to host without an intermediate vehicle or vector. Step 2: Transplacental spread is the classic vertical (direct) route, sexual contact in STDs is direct contact, and direct contact with contaminated soil (for example tetanus or hookworm) is also classed under direct transmission. Step 3: Respiratory or airborne spread relies on droplet nuclei and dust particles suspended in the air, which act as a vehicle carrying the agent, so it is categorised as indirect (airborne) transmission. Step 4: The only option that is not a direct route is therefore the respiratory (airborne) one. \[\boxed{\text{Respiratory}}\]