What term defines an insect or living carrier that transmits an infectious agent from an infected individual or its waste to a susceptible individual or its food?

• A. An insect or living carrier that transports an infectious agent from an infected individual or its waste to a susceptible individual or its food.
• B. A contaminated inanimate object that transmits the disease.
• C. A host that carries the agent without symptoms.
• D. An environment where transmission occurs.

Answer: (A)

Vector transmission refers to a living organism that carries and passes an infectious agent from an infected person or their waste to a susceptible person or their food. Insects like mosquitoes or fleas serve as classic examples, because the pathogen can either multiply inside the vector (biological transmission) or be carried on its body (mechanical transmission). This is distinct from a fomite, which is an inanimate object capable of spreading disease; from an asymptomatic carrier, who harbors the agent without showing symptoms; and from the environment, which is not a living carrier. The description given specifically matches a living carrier that actively moves the pathogen between hosts, which is exactly what a vector does. Therefore, the term is vector.