Estoques de tripanossomas isolados de pacientes na fase aguda da doença de Chagas foram injetados em grupos de camundongos albinos não isogênicos nas doses de 10³, 10(4) e 10(5) parasitas/camundongos. O curso da infecção foi seguido por três meses. A pctrasitemia foi em geral baixa, com picos recorrentes, na maioria das vezes os animais evoluiam para cronicidade. Somente um estoque induziu alto índice de mortalidade. Os parasitas e as lesões apesar de detectadas no pico da parasitemia e restritos ao coração estavam ausentes aos três meses. Nesta época os perfis de Igs apresentaram diferenças marcantes. Grupos de animais que foram inoculados com estes estoques foram desafiados com doses letais da cepa Y ou CL. Em alguns casos obteve-se uma parasitemia, mas patente.

Ten stocks of trypanosomes isolated from patients at the acute phase of Chagas'disease were injected into groups of outbred normal mice at the doses of 10³, 10(4) and 10s5 parasites/mouse and the course of the infections followed up for 3 months. The parasitemia was usually low, with recurrent peaks, the animals evolving to chronicity, only one of them inducing high ratio of mortality. Pattems of parasitemia and mortality were essentially different for each stock studied; only one stock did show similar pattems to well known strains (Yand CL) commonly used in experimental work. Parasites and lesions, although detected at the peak of parasitemia and restricted to heart were absent after three months. At this period the Igs profiles showed striking differences with respect to their distribution. Groups of mice that had been inoculated with one of the stocks were challenged with the Y or CL strains. In some instances low parasitemias although patent were seen after the infecting dose.