Endemic refers to an organism (or phenomenon) naturally occurring in a particular geographic region without having been artificially introduced.
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In biology, an endemic species is one that is native to a specific region, such as the kangaroo being endemic to Australia. The cane toad, on the other hand, was a species introduced to Australia and hence was not endemic (though it is now). In epidemiology, endemic refers to the circulation of a disease within a certain population or geographic area that continues without outside interference or introduction. For example, malaria is endemic to many parts of Africa. Although malaria was once present in the U.S., it would no longer be considered such. Once a disease has been completely eliminated from a geographic region, such as a continent, it is no longer endemic to that region.