title: Biological behavior of Trypanosoma cruzi stocks obtained from the State of Amazonas, Western Brazilian Amazon, in mice.
abstract: BACKGROUND
  The biological diversity of circulating Trypanosoma cruzi stocks in the Amazon region most likely plays an important role in the peculiar clinic-epidemiological features of Chagas disease in this area.
  
  
  METHODS
  Seven stocks of T. cruzi were recently isolated in the State of Amazonas, Brazil, from humans, wild mammals, and triatomines. They belonged to the TcI and Z3 genotypes and were biologically characterized in Swiss mice. Parasitological and histopathological parameters were determined.
  
  
  RESULTS
  Four stocks did not promote patent parasitemia in mice. Three stocks produced low parasitemia, long pre-patent periods, and a patent period of 1 day or oscillating parasitemia. Maximum parasitemia ranged from 1,400 to 2,800 trypomastigotes/0.1 mL blood. Mice inoculated with the T. cruzi stocks studied showed low positivity during fresh blood examinations, ranging from 0% to 28.6%. In hemoculture, positivity ranged from 0% to 100%. Heart tissue parasitism was observed in mice inoculated with stocks AM49 and AM61. Stock AM49 triggered a moderate inflammatory process in heart tissue. A mild inflammatory process was observed in heart tissue for stocks AM28, AM38, AM61, and AM69. An inflammatory process was frequently observed in skeletal muscle. Examinations of brain tissue revealed inflammatory foci and gliosis in mice inoculated with stock AM49.
  
  
  CONCLUSIONS
  Biological and histopathological characterization allowed us to demonstrate the low infectivity and virulence of T. cruzi stocks isolated from the State of Amazonas.
authors.affiliation: Programa de Pós-Graduação em Medicina Tropical, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Universidade do Estado do Amazonas, Manaus, AM. wueltonmm@ibest.com.br
authors.forename: Wuelton Marcelo
authors.initials: WM
authors.lastname: Monteiro
authors.forename: Laylah Kelre Costa
authors.initials: LK
authors.lastname: Magalhães
authors.forename: Josué Costa
authors.initials: JC
authors.lastname: Oliveira
authors.forename: Jorge Augusto de Oliveira
authors.initials: JA
authors.lastname: Guerra
authors.forename: Henrique
authors.initials: H
authors.lastname: Silveira
authors.forename: Luiz Carlos de Lima
authors.initials: LC
authors.lastname: Ferreira
authors.forename: Max Jean de Ornelas
authors.initials: MJ
authors.lastname: Toledo
authors.forename: Maria das Graças Vale
authors.initials: Md
authors.lastname: Barbosa
mesh_terms: D000818:Animals; D001938:Brazil; D014355:Chagas Disease / Q000469:parasitology* / Q000473:pathology; D005838:Genotype; D006801:Humans; D008297:Male; D008394:Marsupialia / Q000469:parasitology; D051379:Mice; D018512:Parasitemia / Q000469:parasitology*; D014225:Triatominae / Q000469:parasitology; D014349:Trypanosoma cruzi / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*