Sonth American Trypanosomiasis 219 



the disease into new districts. Much, too, is being accomplished 

 by moving native villages from the fly belts, (c.f. fig. 137.) 



All measures to avoid the flies should be adopted. This means 

 locating and avoiding the fly belts as far as possible, careful screen- 

 ing of houses, and protection of the body against bites. 



Clearing the jungle along the water courses for some yards beyond 

 the natural range of the fly has proved a very important measure. 

 Castellani recommends that the area be one hundred yards and 

 around a village three hundred yards at least. 



Detailed studies of the parasites and the natural enemies of the 

 tsetse-fly are being undertaken and may ultimately yield valuable 

 results. 



South American Trypanosomiasis The tsetse-flies are distinc- 

 tively African in distribution and until recently there were no tryan- 

 osomes known to infest man in America. In 1909 Dr. Chagas, of 

 Rio de Janeiro described a new species, Trypanosoma cruzi, patho- 

 genic to man. 



Trypanosoma cruzi is the causative organism of a disease common 

 in some regions of Brazil, where it is known as "opilacao." It is 

 especially to be met with in children and is characterized by extreme 

 anemia, wasting, and stunted development associated with fever, 

 and enlargenemt of the thyroid glands. The disease is transmitted 

 by the bites of several species of assassin-bugs, or Reduviidas, not- 

 ably by Conorhinus megistus. The evolution of the parasite within 

 the bug has been studied especially by Chagas and by Brumpt. 

 From the latter's text we take the following summary. 



The adult tryanosomes, ingested by a Conorhinus megistus, of 

 any stage, first change into Crithidia-like forms and then those 

 which remain in the stomach become ovoid and non-motile. Brumpt 

 found these forms in immense numbers, in a Cornohinus which had 

 been infested fourteen months before. The forms which pass into 

 the intestine quickly assume the Crithidia form and continue to 

 develop rapidly under this form. Some weeks later they evolve 

 into the trypanosome forms, pathogenic for man. They then pass 

 out with the excrement of the bug and infect the vertebrate host 

 as soon as they come in contact with any mucous layer (buccal, 

 ocular or rectal). More rarely they enter through the epidermis. 



Brumpt showed that the development could take place in three 

 species ; bed-bugs (Cimex lectularius, C. hemipterus] and in the tick 



