In
epidemiology, an
infection is said to be
endemic (from
Greek ἐν
en "in, within" and δῆμος
demos "people") in a
population when that infection is maintained in the population without the need for external inputs. For example,
chickenpox is endemic (steady state) in the
UK, but
malaria is not. Every year, there are a few cases of malaria reported in the UK, but these do not lead to sustained transmission in the population due to the lack of a suitable
vector (mosquitoes of the genus
Anopheles).