356 



PROTOZOOLOGY 



China, Turkestan, etc.), and in South America. The parasite is most 

 abundantly found in the macrophages, mononuclear leucocytes, and 

 polymorphonuclears of the reticulo-endothelial system of various 

 organs such as spleen, liver, bone marrow, intestinal mucosa, lym- 

 phatic glands, etc. The most characteristic histological change ap- 

 pears to be an increase in number of large macrophages and mono- 

 nuclears. The spleen and liver become enlarged due in part to 

 increased fibrous tissue and macrophages. 



Fig. 148. Leishmania donovani, X1535. a, an infected polymorpho- 

 nuclear leucocyte; b, organisms scattered in the blood plasm; c, an in- 

 fected monocyte; d-f, flagellate forms which develop in blood-agar cul- 

 tures. 



The organism is easily cultivated in blood-agar media (p. 886). 

 After two days, it becomes larger and elongate until it measures 

 14-20/z by 2/i. A flagellum as long as the body develops from the 

 blepharoplast and it thus assumes leptomonad form (Fig. 148, /) 

 which repeats longitudinal division. Dogs are naturally infected with 

 L. donovani and may be looked upon as a reservoir host. Vectors are 

 Phlebotomus argentipes and other species of Phlebotomus. 



L. tropica (Wright). This is the causative organism of the Oriental 

 sore or cutaneous leishmaniasis. It has been reported from Africa 

 (mainly regions bordering the Mediterranean Sea), Europe (Spain 

 Italy, France, and Greece), Asia (Syria, Palestine, Armenia, South- 

 ern Russia, Iraq, Iran, Arabia, Turkestan, India, Indo-China, and 

 China), and Australia (northern Queensland). The organisms are 

 present in the endothelial cells in and around the cutaneous lesions, 

 located on hands, feet, legs, face, etc. 



L. tropica is morphologically indistinguishable from L. donovani, 

 but some believe that it shows a wider range of form and size than 

 the latter. In addition to rounded or ovoid forms, elongate forms are 



