[Polymorphism of Trypanosoma cruzi in the blood of a vertebrate host].

Tetramorphism of trypomastigote forms has been discovered in the blood stream of mice infected with Trypanosoma cruzi, that is C slender, C middle, S slender, S middle and forms intermediate between C and S. Regular changes of forms have been observed in the course of the infection. In the middle of the process, at the moment of maximum destruction of parasites affected by immunosystems of the host, C-forms prevailing on the whole substantially give place to S-forms, slender variants being replaced by middle ones within each of them. Polymorphism in the bloodstream of the vertebrate host is the general property of all trypanosomes, with their common biological value: immunological adaptation to parasitism in the blood and preadaptation to the continuation of the life cycle in the invertebrate host.