88o MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



It is caused by L. donovani (Fig. 184). The parasite is rarely found in the blood; 

 when it is seen there, it almost never occurs free but is found in variable numbers 

 within phagocytic cells. It is, usually, easily found by an examination of the 

 juice obtained from the spleen or lymph nodes by puncture with the needle of a 

 syringe. The liver is enlarged and it, also, contains parasites. As the organisms 

 are seen in preparations of spleen juice, they are small ovals measuring about 2p. in 

 length and i.$p. in width. They consist of cytoplasm, in which lie two chromatic 

 bodies, one of them large and rounded, the other small and rod-like. This form of 

 the parasite may multiply in the body of the host, by binary or multiple division . 



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FIG. 184. Leishmania donovani. Free organisms and several within cells. (After 



Donovan, from Doflein.} 



If spleen pulp, or blood, containing such organisms be placed on a suitable culture 

 medium, they will develop in three or four days, into herpetomonad forms. 

 The large nucleus becomes the trophonucleus of the flagellate form, while the 

 smaller, rod-like mass becomes the kinetonucleus, from which arises the flagellum. 

 The method by which the infection is acquired is unknown; it is probably by the 

 bite of an insect, perhaps a bedbug. 



Kala azar is a chronic disease characterized by emaciation, by an 

 irregular fever and by considerable enlargement of the spleen. There 

 is great loss in strength and energy. 



Although there may be periods of apparent amelioration, the disease 

 usually progresses steadily, in spite of treatment, to a fatal termination. 



INFANTILE KALA AZAR 

 Leishmania infantum Nicolle, 1908 



Most authorities recognize the generalized leishmaniasis which 

 occurs in various countries bordering on the Mediterranean as a distinct 



