The development and pathogenicity of a Trypanosoma cruzi strain ("Chile 5")
of low virulence were studied after infection of nude rats with different
doses of blood trypomastigotes (10-10(7) parasites/rat). Peak parasitemias
were correlated with the infection dose, which also influenced the mean sur
vival times (26-36 days post-infection). Within 26 or 27 days, a subcutaneo
us injection of 10(7) blood trypomastigotes developed to about 8-20 x 10(7)
parasites/ml.