Endemic

Endemic: Present in a community at all times but in relatively low frequency. Something that is endemic is typically restricted or peculiar to a locality or region.

For example, malaria is endemic in some areas of Africa. And traffic in illicit drugs is endemic in some neighborhoods.

By contrast, there are the related terms "epidemic" and "pandemic":

An epidemic is a sudden severe outbreak within a region or a group, as with AIDS in Africa or AIDS in intravenous drug users. A pandemic occurs when an epidemic becomes very widespread and affects a whole region, a continent, or the entire world.

The word "endemic" comes from the Greek "en-", "in" + "demos", "people or population" = "endemos" = "in the population." An endemic is in the people.

By contrast, "epi-" means "upon." An epidemic is visited upon the people. And "pan-" means "all." A pandemic affects all the people.