What term describes the carrier of a pathogen, such as water, air, blood, or an animal?

• A. Carrier
• B. Transmission vector
• C. Reservoir
• D. Disease agent

Answer: (B)

Understanding how pathogens move from one host to another: a transmission vector is anything that carries and transfers the pathogen from a source to a new host. That carrier can be a living organism, like an animal or insect, or a nonliving medium such as water, air, or blood. In this sense, water, air, blood, or an animal can act as a vehicle that delivers the pathogen to a susceptible host, which is why the term transmission vector fits the description in the question.

By comparison, a reservoir is where the pathogen naturally lives and multiplies (for example, in water or animals), a disease agent is the pathogen itself, and a carrier is a host that harbors the pathogen—often without symptoms.