A
natural reservoir or
nidus (the latter from the Latin word for "nest") is the long-term
host of a
pathogen of an
infectious disease. Hosts often do not get the disease carried by the pathogen or it is carried as a
subclinical infection and so
asymptomatic and non-lethal. Once discovered, natural reservoirs elucidate the complete life cycle of infectious diseases, providing effective
prevention and control.