What is the difference between a reservoir and a source? Provide an example of a source and explain why it is a source.

A reservoir and a source are two terms often used in the context of disease transmission, but they can also refer to other things like water bodies or oil deposits.

1. Reservoir: A reservoir is a place where something is stored or where it can be found. In the context of disease transmission, a reservoir refers to any person, animal, plant, soil or substance in which an infectious agent normally lives and multiplies. The reservoir typically harbors the infectious agent without injury to itself and serves as a source from which other individuals can be infected. For example, rats can be a reservoir for the bubonic plague.

2. Source: A source, on the other hand, is the point of origin or the place from which something comes. In the context of disease transmission, a source refers to the person, animal, object or substance from which an infection is directly transmitted to the host. The source of infection is usually the reservoir or a person or animal infected from the reservoir. For example, a person with tuberculosis can be a source of infection to others.

So, the main difference between a reservoir and a source is that a reservoir is where an infectious agent normally lives and multiplies, while a source is the point from which the infection is directly transmitted to the host.

An example of a source is a mosquito that carries the malaria parasite. The mosquito is a source because it is the point from which the malaria infection is directly transmitted to humans. The mosquito gets the parasite by biting an infected person or animal (the reservoir), and then it transmits the parasite to humans when it bites them.