CHAPTER LXI. 

 PARASITES OF THE GENUS LEISHMANIA. 



1. Leishmania donovani, p. 797. 2. Leishmania infantum, p. 800. 3. Leish- 

 mania tropica, p. 802. 4. Other species of Leishmania, p. 802. 



1. Leishmania donovani. 



Synonym. Piroplasma donovani. 



IN 1900 Leishman demonstrated [in the spleen of a man who had been 

 invalided for and who died of dum-dum fever l ] certain parasitic forms which 

 he suggested might be Trypanosomes. In 1903 Donovan found the same 

 parasite in the smears of the spleen taken from patients dying of a similar 

 disease in Madras, and Bentley subsequently found them in patients suffering 

 from Kala Azar, a very fatal disease found in Bengal and Assam. 



The Leishman-Donovan parasite was originally classified by Laveran and 

 Mesnil with the piroplasmata : Ross however created for it a new genus 

 Leishmania. Marchand and Ledingham consider that the parasite is a Try- 

 panosome while Rogers [and Patton] group it with the genus Herpetomonas. 



Methods of detecting the parasite. Its appearance in the tissues. The 

 parasite occurs characteristically in the endothelial cells of the blood and 

 lymphatic vessels : it is present in very large numbers in the spleen, liver 

 and bone marrow, and is also found in the lungs, kidneys, mesenteric glands 

 and in the ulcers in the large intestine. In the peripheral blood it occurs in 

 small numbers within the polymorpho- and mono-nuclear leucocytes and 

 very occasionally in the red cells. Its presence in the blood is very likely to 

 be missed so that several preparations should be examined before coming to a 

 negative conclusion : in the last stage of the disease, however, and during 

 febrile attacks the parasite may be present in large numbers in the blood- 

 stream (Donovan). 



Blood-films should be prepared and examined in the first instance and 

 should the parasite not be found the spleen may be punctured and films 

 stained. Puncture of the spleen, however, is always a risky proceeding : it 

 is better to puncture the liver. Use a quite dry, sterile syringe with a fine 

 needle : the results are more satisfactory if no blood be drawn. Expel the 

 material in the needle on to slides, spread films, dry, stain with Giemsa's or 

 Leishman's stain and examine with an oil-immersion lens. 



1 [Dum-dum fever is so called from Dum-dum an unhealthy cantonment near Calcutta. ] 

 The disease is a severe form of cachexia accompanied by fever, anaemia, hypertrophy of 

 the spleen, wasting of the muscles and diarrhrea. It used also to be described as tropical 

 splenomegaly but is now known to be the same disease as Kala Azar. 



