ENDEMIC (from Gk. irdvpos, endt7mos, na tive, from iv, cn, in di/pos, (Icarus, people). A tern: applied to diseases which affect numbers of persons simultaneously, but so as to show a con nection with localities as well as with their in habitants. Endemic diseases are usually spoken of as contrasted with epidemic (q.v.) and spo radic (q.v.), the first term indicating that a dis ease infests habitually the population within cer tain geographical limits, and also that it is incapable of being transferred or communicated beyond those limits; while, on the other hand. a disease is termed epidemic if it is transmitted without reference to locality, and sporadic if it occurs in isolated instances only. The theory, accordingly, of endemic diseases is, that they are in some way or other connected with the soil, the climate, the water-supply, the customs of the people, and the microbes natural to the locality. The most marked types of an endemic disease are intermittent fever in many parts of the United States, or yellow fever in Brazilian coast districts. Terrestrial miasms, or such poisons as weaken resistance and invite the attacks of endemic diseases, are usually found in the neighborhood of marshy flats, or of un cultivated tracts of land at the confluence of rivers, or where a delta, or a wide channel sub ject to overflow, is formed at the upper end of a lake. In proportion. too, as the heat of the
sun is greater, the tendency to malarious emana tions is increased; and in the tropics, according ly, large tracts of jungle and forest are often rendered absolutely uninhabitable and almost impassable at certain seasons by the invisible and odorless germs of fevers. Such diseases are almost always sudden in their mode of attack, and they indicate the range of their influence by the number of persons attacked; but they are wholly free in most cases from the suspicion of communication by contagion (q.v.), which is so frequent in the case of epidemic diseases. They are in all cases due to animal or vegetable dis ease germs, transmitted to the weakened indi vidual by the bites of various insects, or through drinking-wate•, or water used in washing cooking utensils and table-ware.