ECOLOGY, COMMENSALISM AND PARASITISM 369 



was given in 1903, following a remarkable series of clear-cut observa- 

 tions which appeared in rapid succession. On May 30, 1903, 

 Leishman published some observations, which he had made a couple 

 of years before on peculiar intracellular bodies found in cases of 

 dum dum fever. These he interpreted as evidence of trypano- 

 somiasis in India. On July 11th, Donovan observed peculiar bodies 

 in the peripheral blood of cases of kala azar. Preparations were 

 sent to Laveran and Mesnil who regarded the "Leishman bodies" 

 as similar to parasites (Babesia) of mammalian erythrocytes and 

 on November 3rd named the organism Piroplasma donovani. On 

 November 14th and 28th Ross published his conclusions that the 

 " Leishman-Donovan bodies" are not Trypanosomes (Leishman) 

 but a new type of organism which he named Leishmania. The cor- 

 rect name of the peculiar organism of dum dum fever or kala azar 

 was thus established as Leishmania donovan i. The series of observa- 

 tions was not yet complete, however, for in December, 1903, Wright 

 published the results of his study of a case of tropical ulcer which 

 was treated in a Boston hospital, and he named the organism 

 Helcosoma tropica. Its resemblance to the Leishman-Donovan 

 bodies was soon recognized, but skeptics refused to admit that the 

 " Leishman-Donovan- Wright bodies" are organisms and held that 

 they might be the results but not the causes of these diseases. 

 All such doubts were dispelled, however, in 1904 when Rogers 

 cultivated in vitro material taken from infected blood and spleen 

 cells and demonstrated the transformation of the disputed " bodies " 

 into actively moving flagellated parasites. 



Further discoveries followed. Nicolle, in 1908, found a similar 

 organism in cases of infantile ulcer which he named Leishmania 

 infantum, and Vianna (1911) discovered the cause of a South 

 American disease known as espundia, which he named Leishmania 

 braziliensis. 



Clinically there appear to be two types of human leishmaniasis — 

 visceral and cutaneous. The former is characteristic of dum dum 

 fever, also called kala azar (black sickness), the latter of infantile 

 ulcer, tropical ulcer and Brazilian leishmaniasis. Structurally 

 the several species are indistinguishable, but serologically L. donovani 

 and L. infantum are apparently the same, both differing from L. 

 tropica and L. braziliensis. In regard to the specificity of the last 

 two there is considerable difference of opinion. Reichenow-Doflein 

 accepts them as independent species while Wenyon considers the 

 evidence inconclusive. L. tropica is the cause of localized cutaneous 

 diseases which are widely distributed geographically and known as 

 Oriental sore, Delhi sore, Aleppo boil, Bagdad sore, tropical ulcer, 

 Nile ulcer, etc. i. braziliensis causes a similar localized initial 

 cutaneous sore, which heals, but some time later, it may be months, 

 the parasites reappear in the mucous membrane of mouth, nose 

 24 



