To study the injluence ofthe intermediate host stage on the course of mouse infection, Trypanosoma cruzi belonging to the Peruvian (Type I), 12 SF (Type II) and Colombian (Type 111) strains were passaged through either Rhodnius prolixus, Panstrongylus megistus or Triatoma infestans. T. cruzimetacyclicforms (dose 10*) from the different strains were obtained from each bug and inoculated into 8-10 gm mice. Comparison was made in mice inoculated with bloodforms. Parasitaemia curves were plotted in the peripheral blood for each strain, reaching more elevated peaks with Peruvian strain parasites from P. megistus and R. prolixus, 12 SF strain from P. megistus and Colombian strain from R. prolixus. Tissue tropism and histopathologiealpatterns were those usually seen in mice infected with each respective strain type. Peruvian virulence was the same for all groups. Slender forms predominate among mice inoculated with metacy clic forms of Colombian and 12 SF strains, probably an adaptative parasite change related to the intermediate host.
Trypanosoma cruzi; Triatominae; T. cruzi strains; Biological characters; Vectors