endemic

1. Relating to a disease or pathogen that is found in or confined to a particular location, region, or people. Malaria, for example, is endemic to tropical regions. See also epidemic, pandemic.

2. Native to a specific region or environment and not occurring naturally anywhere else. The giant sequoia is endemic to the western slopes of the Sierra Nevada. Compare alien, indigenous.

Our Living Language  : A disease that occurs regularly in a particular area, as malaria does in many tropical countries, is said to be endemic. The word endemic, built from the prefix en-, "in or within," and the Greek word demos, "people," means "within the people (of a region)." A disease that affects many more people than usual in a particular area or that spreads into regions in which it does not usually occur is said to be epidemic. This word, built from the prefix epi-, meaning "upon," and demos, means "upon the people." In order for a disease to become epidemic it must be highly contagious, that is, easily spread through a population. Influenza has been the cause of many epidemics throughout history. Epidemics of waterborne diseases such as cholera often occur after natural disasters such as earthquakes and severe storms that disrupt or destroy sanitation systems and supplies of fresh water.