Final answer:
A host reservoir is an organism or environment that normally harbors a pathogen. Examples include various animals like birds and insects, or environments such as soil and water.
Step-by-step explanation:
The organism or environment that normally harbors a pathogen is known as a host reservoir. An organism, such as a bird, rat, horse, insect, or human, or an environment, like soil or water, can serve as a host reservoir. This term refers to the natural living space of the pathogen where it can survive, multiply, and be transmitted to a susceptible host. The term pathogen carrier often applies to an organism that harbors the pathogen but does not exhibit symptoms of the disease. A disease vector is an organism like a tick or mosquito that transmits a pathogen from one host to another without necessarily being affected by the pathogen itself. Lastly, an infection source refers to the specific origin from which an infectious agent is immediately transmitted to a host, this could be an infected individual or a contaminated object or environment.