Transboundary Emerging and Exotic Animal Disease/ Exotic Animal Disease Practice Exam

What defines a reservoir host?

1. Never show clinical signs of infection

2. Almost always show clinical signs of infection

3. Serve as a habitat in which the pathogen can survive

4. Transmit infectious agents by aerosol spread

The correct answer is: Serve as a habitat in which the pathogen can survive

A reservoir host is defined as a species or population that harbors a pathogen and facilitates its survival and continuity within the environment. This concept is crucial in understanding the dynamics of diseases, as a reservoir host can be a source of infection for other susceptible hosts. The defining characteristic of a reservoir host is its role in the ecosystem, specifically its capacity to allow the pathogen to persist, even if the reservoir itself does not exhibit signs of illness. This capacity to provide a habitat where the pathogen can survive is essential for the pathogen's life cycle, allowing it to infect new hosts during various transmission events. While some reservoir hosts may show clinical signs of infection, this is not a requirement for them to fulfill their role effectively, which is why the notion of being asymptomatic, although related, does not define a reservoir host as clearly as its ability to serve as a habitat for the pathogen. The other options touch on particular aspects or outcomes of the interaction between hosts and pathogens, yet they do not encapsulate the primary function of a reservoir host in the disease ecology. For instance, while some reservoir hosts may transmit infectious agents through various means, such as aerosol spread, this attribute is not a defining characteristic of reservoir hosts in general.