What is a reservoir host?

• A. People, insects, animals, water, food, or contaminated instruments or equipment
• B. A person who transmits pathogens directly to others
• C. An environment where pathogens cannot survive
• D. A host that becomes immune

Answer: (A)

A reservoir host is any organism or environment in which a pathogen can live, persist, and potentially multiply, providing a source from which infection can spread. This includes living carriers like people, insects, and animals, as well as non-living reservoirs such as water, food, or contaminated instruments or equipment. The key idea is that the reservoir is where the pathogen naturally resides and remains capable of causing infection in others.

The other options miss that broad idea: a person who transmits pathogens directly to others describes how disease can spread, but not the habitat or source where the pathogen survives; an environment where pathogens cannot survive is exactly the opposite of a reservoir; a host that becomes immune relates to the immune response, not where the pathogen persists to spread.