: a host organism in which an infectious agent (such as a bacterium or virus) that is pathogenic for some other species lives and multiplies typically without damaging the host Note: A reservoir serves as a source from which transmission of infection and outbreaks of disease can occur.
It is the white-footed mouse that serves as a natural reservoir host for the spirochete B. [Borrelia] burgdorferi. These mice carry the spirochete without any apparent harm to themselves, and it is through feeding on infected mice that the immature stages of the tick acquire the spirochete. Suzanne Clothier et al. also : a nonliving thing (such as soil or water) in which an infectious agent lives and multiplies and which serves as a source of infection similar to a host organism