=General Considerations.=—There is good reason to believe that much that was written about oriental sore prior to our knowledge of its etiology referred to tuberculous, syphilitic and other ulcerative skin lesions. As regards the work done in the investigations as to etiology Cunningham, in 1885, described deeply staining bodies in cells which were larger than lymphocytes. Later, in 1901, Firth confirmed the findings of Cunningham, but considered the bodies as degenerative changes in the cells rather than entertaining the view of Cunningham that they were parasitic protozoa. The name _Sporozoa furunculosa_ was given these parasites. As previously stated, Wright, in 1903, using his modification of the Romanowsky stain, found round or oval bodies, from 2 to 4µ in diameter, packed in the cytoplasm of endothelial cells, in smears from an oriental sore in a child from Armenia. He called the parasites _Helcosoma tropicum_. [Illustration: FIG. 55.—_Leishmania tropica._ Smear from granulation tissue of Delhi boil or oriental sore. (MacNeal from Doflein after J. H. Wright.)] As the result of our knowledge that such lesions are caused by leishman bodies, _Leishmania tropica_, we have been forced to include among such sores clinical types entirely different from the classical oriental sore of Fayrer or Tilbury Fox. Even a keloid type of lesion described by the workers in the Sudan is known now to be caused by leishman bodies. In 1909 leishman bodies were demonstrated in ulcerative processes from Brazil and since that time we have divided cutaneous leishmaniasis into two groups, according to geographical distribution, that of the East, or oriental sore, and that of the West, or American leishmaniasis. Oriental sore is found chiefly in North Africa, Asia Minor, Syria, Persia and India, and more recently cases have been reported from Italy and Greece and New Caledonia. American leishmaniasis is found chiefly in Central America, Brazil, Peru and the Guianas. =Epidemiology.=—There is nothing definite known as to the epidemiology of cutaneous leishmaniasis. The fact that oriental sore almost always occurs on the uncovered parts of the body would suggest transmission by some insect as the house fly or mosquito rather than by the body louse, flea or bedbug, these latter showing no special preference for the uncovered skin.