Data showing differences in the interaction (differentiation and multiplication) o/Trypanosoma cruzi Yand CL strains ("polar strains ”), in Triatoma infestans Panstrongylus megistus and Dipetalogaster maximus are presented. It is concluded that with T. infestans 40% of the individual bugs have accentuated resistance to infection with the Y strain of T. cruzi. P. megistus was found to be a good vector to the studied strains presenting good development and differentiation of the parasites with low percentage of rejection of infection. Better development and differentiation is shown by D. maximus which is indicated for xenodiagnosis in Chagas' disease. The authors suggest the presence of two factors responsible for this vector-parasite interaction: a resistance factor to infection, perhaps related to the presence of nutrients, and also a factor that regulates differentiation to metacyclic forms of T. cruzi.
Trypanosoma cruzi-vtctor interaction; Xenodiagnosis; Infection resistance factor; Differentiation