South 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 Reduviidae, 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-hke 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 
