of 1832. During the same summer it crossed the Atlantic to Canada and the United States. This epidemic did not die out in Europe till 1839. Since that time there have been at least five European epidemics— 1848-51, 1851-55, 1865-74, 1884-86, and 1892-95. Minor epidemics have occurred in Europe since, but they have been restricted in area. During the Balkan War of 1913, and in the course of the European War, especially in the Balkans and in Mesopotamia, there have been many outbreaks of cholera, but up to the present the disease has not extended as an epidemic beyond the seat of war.
Great Britain has been seriously involved in four only of these epidemics— namely, in 1832, 1848, 1854-55, and in 1866. On the occasion of the last two European epidemics, although the disease was frequently imported, it did not spread in Britain. America has not been so fortunate, for, although the 1870-73 epidemic practically spared Great Britain, it crossed the Atlantic and, entering by way of Jamaica nd New Orleans, raged for a time in the United States.
From a study of the march of these various epidemics, it is to be concluded that cholera reaches Europe by three distinct routes: (1) via Afghanistan, Persia, the Caspian Sea, and the Volga valley; (2) via the Persian Gulf, Syria, Asia Minor, Turkey in Europe, and the Mediterranean; (3) via the Red Sea, Egypt, and the Mediterranean.
With certain exceptions, hereafter to be mentioned, there is hardly an important country in the world which has not, at one time or another, been visited by cholera in the course of some of its pandemic extensions.
Etiology.— The disease is carried by man.— A study of the various epidemics shows that in its spread cholera follows the great routes of human intercourse, and that it is conveyed chiefly by man—probably in its principal extensions by man alone —from place to place. In Britain and the United States, for example, the places first attacked have been invariably seaports in direct and active com-
