The vector, a species of triatomid bug, may ingest the typanosome 
stage in the blood or the leishmania stage within a macrophage 
during feeding. In the bug midgut the parasite becomes the flagellated 
crithidial form and multiplies. The organisms then migrate to the 
hindgut where they become metacyclic or infective trypanosomes. 
These forms passed in the feces discharged as the bug feeds, 
ordinarily enter the mammalian host by being rubbed into the bite 
wound. 
The triatomid species incriminated as vectors are Panstrongylus 
megistus , Triatoma infestans (southern South America), T. dimidiata 
(Central America) and Rhodnius prolixus (northern South America 
and Central America). 
Both domestic and wild mammals serve as reservoir hosts 
including dogs, cats, pigs, armadillos, and rodents among others. 
The second American species, T. rangeli, morphologically is 
more nearly like the African trypanosomes than like T. cruzi . How- 
ever, in its choice of a vector, a genus of triatomid bugs, it resembles 
the latter. The life cycle differs from that of T. cruzi in the following 
aspects: the metacyclic trypanosomes in the vector gain access to 
the vertebrate host through the bite of the bug as well as through 
fecal contamination of the bite wound as occurs in T. cruzi; no 
leishmania stages have been found in the vertebrate host. T. rangeli 
has been reported from northern South America and from Central 
America. 
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