SCHIZOTRYPANUM CRUZ I 



427 



C brucei are susceptible to C. rhodesiensis. Is C. rhodesiensis a 

 variety of T. pecaudi ? No, because the former is more virulent than 

 the latter to animals, and because sleeping sickness is unknown in the 

 region where ' baleri ' is intense, and, finally, because an animal 

 immunized against C .rhodesiensis is not immune against T. pecaudi. 



We may therefore conclude that C. rhodesiensis Stephens and 

 Fantham, 1910, is a good species. 



Cultures. — 'Thomson has cultured it with partial success on a 

 modification of the Novy-McNeal-Nicolle medium. 



Vertebrate Reservoir. — It is claimed that the larger game animals 

 are the reservoir of this trypanosome. 



Pathogenicity. — C. rhodesiensis is the cause of one form of sleeping 

 sickness. 



Schizotrypanum cruzi Chagas, 1909. 



Synonym,— Trypanosoma cruzi Chagas, 1909. 



History. — This trypanosome was discovered by Chagas in the 

 intestine of Larnus megistus Burmeister in Brazil, and later it was 

 found in the blood of a child suffering from irregular fever, pro- 

 gressive anaemia, and enlargement of various groups of lymphatic 



Fig. 113. — Schizogony of Schizotrypamim cruzi Chagas. 

 (After Chagas.) 



I, Merozoite in red blood cell; 2, parasite totally enclosed in red cell, no 

 flagellum or undulating membrane; 3-5, parasites partially enclosed in red cell; 

 6, 7, parasites in human blood; 8-1 1, parasites in the lungs of Callithrix; 

 12, 13, initial forms of schizogony; 14, 15, schizogony in the lungs of Callithrix. 



glands. The trypanosome was characterized by the presence of a 

 large kinetonucleus, and by the facility with which it could be 

 cultivated on blood agar. In 1910-11 Chagas published a series 

 of papers upon the life-history of the parasite and the symptoma- 

 tology of the disease which it produces. In 191 1 Vianna studied 

 the pathological anatomy, while further studies on the parasite, 

 were made by Brumpt, Martin Mayer, Rocha-Lima, and others. 



Morphology. — In the peripheral blood of man S. cruzi appears in 

 two forms— either free or in the red blood-corpuscles. 



