MASTIGOPHORA 1093 



has no flagellum and resembles the leishmania; only after escape into 

 the blood does it take 011 the trypanosome form. 



Guinea-pigs, rats, mice and monkeys are susceptible; the bed- 

 bug, cimex, is also capable of transmitting the disease. 



Cultures were obtained by Chagas and proved virulent for 

 animals. The human disease is found both in children and adults 

 and is regularly fatal. It is characterized by an irregular fever, 

 severe anemia, swelling of the lymph nodes, edema and disturbance 

 of the nervous system. Two quite distinct forms are recognized, 

 the acute, which is usually found in young children, and the chronic, 

 found in adults. The acute form is characterized by fever, a myxe- 

 dematous swelling of the face and neck or even the whole body, 

 and the presence of trypanosomes in the circulating blood. The 

 nervous system may be involved in the acute cases, in which event 

 they end fatally. The chronic form has no trypanosomes in the 

 blood, but has foci, or cysts in the heart, the voluntary muscles or 

 in the viscera or the nervous system. Disturbances of almost any 

 part of the body may result. While the foci may be generalized 

 they do not follow the blood vessels. 



Leishmania. This genus was founded by Boss in 1903 for the 

 Leishman-Donovan and Wright bodies found in kala-azar and Delhi 

 boil, to which Nicolle added another in 1909, the parasite of infantile 

 splenomegaly. Leishman, Donovan and Wright, working independ- 

 ently, described the first two parasites in 1903, and, although they 

 have received various names, leishmania is now the accepted term. 

 Rogers, Calkins and others, however, class them as herpetomonads, 

 because of the elongated, flagellated form all take in cultures on the 

 Novy-MacNeal-Nicolle blood agar medium. It is, however, best to 

 consider them as a separate genus, because of their natural parasitic 

 habits in human beings. Leveran, Fantham and others have shown 

 that it is possible in the laboratory to induce the herpetomonads 

 parasitic in the intestine of various insects to become parasitic in 

 various vertebrates. 



Leishmajiia donovani (Kala-azar). This parasite is the cause of 

 kala-azar, a disease characterized by irregular fever, weakness, 

 anemia, cachexia and a remarkable enlargement of the spleen, and 

 occasionally of the liver. It is chronic, progressive and frequently 

 fatal, the mortality being about 80 to 90 per cent. This disease is 

 common in tropical Asia and in northeastern Africa. 



Morphology. The parasite is intracellular, and is found prin- 



