Endemial (ἐν ὀνομασίᾳ, ἐν τῷ πολίτευσι, the people), peculiar to a people or nation. Endemic diseases are those to which the inhabitants of a particular district are peculiarly subject, and which, for that reason, are attributed Endogens to such causes as bad air or water, or the manner of living. Thus agues or intermittent fevers are endemic in low marshy districts; the goitre in the Alps; plica trichosis or Polonica in Poland.

Epidemic, again, is applied to those diseases which, independently of such causes, seize many persons at or about the same season, in the same country or district. Thus, influenza, measles, scarlet-fever, &c., are sometimes epidemic. It may be observed—that according to the medical notion of the term, it is essential that the prevalence of the disease be temporary.