The location or organism where disease-causing agents exist and maintain their ability for infection.

It is the reservoir. It is the long haul host of a pathogen of an irresistible infection. Has regularly don't get the sickness conveyed by the pathogen, or it is conveyed as a subclinical disease as is asymptomatic and non-deadly. 

A reservoir is an irresistible specialist ordinarily lives and increases, on which it depends basically for survival, and where it replicates itself in such way that it can be transmitted to a vulnerable host.