LEISHMANIA 



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Crithidia melophagia Flu, 1908. 



Flu has described Crithidia melophagia in Melophagus ovinus, a parasite of 

 the sheep. He gives an account of asexual and sexual reproduction. The 

 latter is characterized by a process of reduction, followed by conjugation with 

 the formation of an ookinete and the infection of the eggs of the insect, which 

 may cause a second generation of flies to carry the organism (Fig. 90). 



Other Species. — C . fasciculata Leger, 1902, in the intestines of females of the 

 species Anopheles maculipennis and in Culex fatigans Wied.; C. campanulata 

 Leger, 1903, in the intestine of Chironomus plumosus ; C. minuta Leger, 1903; 

 this parasite is found in Tabanus tergestinus , and is characterized by having 

 a thick rounded end; C. cleti Hindle and Lewis, 1912, in Cletus varius Dall, 

 C. pulicis Porter, 191 1, in Pulex irritans L., C. hy sir ichopsy lice Mackinnon, 

 1909, in Hystrichopsylla talpcs, and a number unnamed by Miss Robertson 

 in Hemiptera in Uganda; Crithidia hyalommcB O'Farrell, 1913. 



Genus Leishmania R. Ross, 1903. 



Synonyms. — Piroplasma Laveran and Mesnil, 1903, Helcosoma 

 Wright, 1903, H&rpetomonas Rogers, 1904. 



Definition. — -Herpetomoninae, living principally in endothelial 

 cells, but also found in leucocytes and in the peripheral blood of 

 mammals as small, oval, cytoplasmic masses with tropho- and 

 kineto-nuclei, and developing into flagellate bodies in cultures. 



Remarks. — -Three species are known in man, morphologically 

 similar, but pathogenetically different: Leishmania donovani 

 Laveran and Mesnil, 1903, L. infanhtm Nicolle, 1908, and L. tropica 

 Wright, 1903, and probably there are other varieties. 



With regard to these species there is a general consensus of opinion 

 that L. tropica, with its variety americana, is distinct from L. dono- 

 vani and L. infantum. In respect to the two last-named forms it 

 has been argued that they are identical because : — 



I . Both attack adults and children. 



II. A monkey immunized against L. infantum is refractory to 

 L. donovani. 



On the other hand, there are some differences, viz. : — 



I. It is true that both attack adults and children, but the latter 



are much more easily infected by L. infantum. 



II. L. infantum infects dogs readily, while these are more 



refractory to L. donovani. 

 III. L. infantum, according to one experiment by Nicolle and 

 Manceaux, only produces a local cutaneous lesion when 

 inoculated under the skin of a monkey, while L. donovani, 

 under similar conditions, according to Row and Korke, 

 produces a local cutaneous lesion, with or without a 

 general infection, when inoculated into or under the skin. 



For the present we shall treat L. donovani and L. infantum as 

 separate parasites. 



The Sudan parasite is considered by Archibald to be distinct 

 from L . infantum because : — 



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