1284 



SOUTH AMERICAN TRYPANOSOMIASIS 



hinus geniculatus) of the family Reduviidse is one of the carriers of 

 the same trypanosome. He also believes that Triatoma infestans 

 and T. sordida may be carriers. It may be stated that T. gmiculata 

 lives in the burrows of the armadillo, the flesh of which is rather a 

 delicacy. 



With regard to the history of the discovery of a trypanosome in man in 

 South America, Sambon informs us that in 1904 de Lacerda published a 

 paper entitled ' Etiologia de Beri-Beri ' in the Brazil Medico, in which he 

 stated that he had found trypanosomes in films taken from the spinal cord of 

 a case of beri-beri. We have been unable to obtain this paper, and therefore 

 cannot verify the statement, nor can we say whether the disease, which de 

 Lacerda was considering, was beri-beri or some other complaint. It would, 

 however, be interesting to have this historical problem elucidated. 



Climatology.— The disease is known among the poorer inhabitants 

 of the State of Minas in Brazil, where it appears to attack the whole 

 population, so that the children all become affected and either 

 recover, die, or pass into the chronic stage. 



etiology. — ^The disease is caused by Schizotrypanum cm^^'Chagas, 

 1909. This tr3/panosome, which is remarkable because of the large 

 size of its kinetonucleus, is capable of being transmitted by Lamus 

 megistus, and perhaps by species belonging to other genera of the 

 Reduviidae — e.g., Triatoma — to domestic animals and to man. 

 The reservoir of the trypanosome appea^rs to be an armadillo — 

 Dasypus novamcinctus. 



In the blood three forms are seen: the first with a large nucleus 

 and loose chromatin and a terminal kinetonucleus; the second 

 narrower, with an oval nucleus and dense chromatin; the third 

 with a long nucleus. The parasite undergoes schizogony in the 

 lungs, after which the merozoites enter the red blood cells and 

 become trypanosomes again. Sporogony takes place in the bug 

 Lamus megistus, the tinal forms being found in the salivary glands, 

 from whi'ch they pass during the act of biting into the verte- 

 brate. (For a description of the parasite and its life-history, see 

 Chapter XIX., p. 427.) 



Pathology. — ^The tryptinosomes enter the cells of the various 

 tissues and organs of the body, but especially those of the muscular 

 system, and more particularly those of the muscles of the extremities 

 and back. Inside these cells they assume Leishmania-hke forms 

 without fiagella, but provided with trophonucleus and kinetonucleus. 

 These forms divide by binary division, and so increasing in numbers, 

 dilate the cell considerably. During this process there is no reaction 

 upon the part of the surrounding tissue, but after a time the cell 

 membrane ruptures, and the parasites which have already become 

 flagellate inside the dilated remains of the cell, which is virtually 

 a cyst, escape. With this escape of the parasites into the tissues 

 the local inflammatory reaction appears, and with the appearance 

 of the trypanosomes in the blood the general symptoms make 

 themselves evident. Whether the parasites produce any toxins 

 or not is unknown, but it is probable that they do so, because of the 



