Diagnosis. — The diagnosis of dysen tery usually involves no great difficulty.
The characteristic evacuations are path ognomonic. The diseases from which it is to be discriminated are local affections of the rectum, such as syphilis and epi thelioma, which may produce tenesmus with the passage of mucoid and bloody stools, and hemorrhoids, and a discharg ing intestinal abscess, in which certain of the symptoms are simulated.
Etiology and Epidemiology.—Dysen tery is one of the four great epidemic dis eases of the world. In the tropics it destroys more lives than cholera, and it has been more fatal to armies than pow der and shot (Osler). From the ac counts furnished by history and the numerous ones supplied by physicians in the last three centuries bearing upon its epidemiology, it may be concluded that, just at present, dysentery has at all times had the widest distribution over the globe and that no considerable part has been exempted from a visitation. To quote Ayres, "of dysentery it may be said that, where man is found, there will some of its forms appear." The present geographical distribution of dysenteric and diarrhceal diseases is compared by Hirsch with that of the malarial diseases, with which, in respect to the manlier of their endemic preva lence, the frequency of their epidemic outbreaks, and the varying severity of their type, they are in correspondence.
Like the malarial diseases, they reach the maximum of diffusion and of inten sity, and more especially their greatest severity as an endemic, in equatorial lati tudes; in subtropical countries there be °ins to be noticed a decrease in the ex tent and seriousness of endemic and epi demic incidence; while in still higher latitudes they almost disappear as en demic diseases and show themselves merely now and then in epidemics over an area at one time large and another time small. In one point they differ from malarial diseases, namely: that they attain to higher latitudes of the cold zone, appearing as epidemics in re gions that are quite free from malaria.
The endemic form of dysentery has al ways existed in Africa and India, but the place of its natural home is not known. Its present distribution includes Africa in its entire extent, except for a few lo calities. Both natives and Europeans are affected. In South Africa it prevails se
verely in Bechuanaland, Natal, and the Transvaal. In the north it appears in Egypt, especially along the coast and the Nile delta. In Asia it prevails to a great extent along the Arabian coast of the Red Sea as well as of the Gulf of Aden and the Persian Gulf. It exists in Syria, Asia Minor, and extends into Mesopo tamia and Persia. Endemic dysentery is widely disseminated in India and the Indian Archipelago and exists in China. In Japan it assumes a milder form, while the epidemic variety is very destructive. The disease prevails in the tropical and subtropical parts of South America, but it fails to reach the wide diffusion which it presents in Africa and India. In Guiana it is found in the mountainous regions and in the tropical parts of Brazil in a severer form. In Valparaiso and La Serena in Chile the disease has a home. Foci appear in Paraguay and in the tropical provinces of Argentine Re public. In Peru it occurs along the marshy districts of the Amazon and in some of the mountainous regions, being endemic in the city of Cero de Pasco at an elevation of 13,000 feet. Venezuela does not escape; in -Uruguay it is almost unknown. In Central America the dis ease prevails in Panama, Costa Rica, Nicaragua, Salvador, Honduras, and Gautemala. It is diffused over Mexico and appears at elevations of 0000 feet.
It assumes the severest forms in the West Indies, especially in Cuba and Hayti, and prevails to a greater or less extent in Guadeloupe, Martinique, and Barbadoes. In Europe endemic dysentery occurs over limited areas only, and is present in the more southernly-placed countries. Thus it is known in Greece, but is endemic in the Ionian Islands and the Cyclades. In Turkey it is common, in Bulgaria and Roumania, along the Donau, also, while the southern provinces of Italy and Sic ily are the most severely affected regions in Europe. France, Switzerland, Bel gium, the Netherlands, and Great Britain are free from endemic dysentery. In Germany there are no definite foci of occurrence, but a number of cases of the disease have been observed at -Weimar and Kiel. The same facts are true of Austria, which, in general, has escaped, although cases have been reported from Prague, Graz, and Vienna.