402 Fundamentals Exam 1 Practice 2026 - Free Practice Questions and Study Guide

The term describes the natural habitat of an organism is reservoir. In infectious disease terms, a reservoir is the place where a pathogen normally lives, grows, and persists in nature. It can be a living host (such as humans or animals) or an inanimate environment (like soil or water). The key idea is persistence and suitability for survival, not necessarily causing disease in that host. This distinguishes it from other concepts: a portal of exit is how the pathogen leaves its reservoir or host, a means of transmission is how it moves from one host to another, and a portal of entry is how it enters a new host. For example, certain pathogens are kept in wildlife species or environmental settings and can spill over to humans, illustrating how the reservoir maintains the organism until transmission occurs.