title: Trypanosoma cruzi strain TcI is associated with chronic Chagas disease in the Brazilian Amazon.
abstract: BACKGROUND
  Chagas disease in the Amazon region is considered an emerging anthropozoonosis with a predominance of the discrete typing units (DTUs) TcI and TcIV. These DTUs are responsible for cases of acute disease associated with oral transmission. Chronic disease cases have been detected through serological surveys. However, the mode of transmission could not be determined, or any association of chronic disease with a specific T. cruzi DTU's. The aim of this study was to characterize Trypanosoma cruzi in patients with chronic Chagas disease in the State of Amazonas, Brazil.
  
  
  METHODS
  Blood culture and xenodiagnosis were performed in 36 patients with positive serology for Chagas disease who participated in a serological survey performed in urban and rural areas of Manaus, Amazonas. DNA samples were extracted from the feces of triatomines used for xenodiagnosis, and the nontranscribed spacer of the mini-exon gene and the mitochondrial gene cytochrome oxidase subunit II (COII) were amplified by PCR and sequenced.
  
  
  RESULTS
  Blood culture and xenodiagnosis were negative in 100% of samples; however, molecular techniques revealed that in 13 out of 36 (36%) fecal samples from xenodiagnosis, T. cruzi was characterized as the DTU TcI, and different haplotypes were identified within the same DTU.
  
  
  CONCLUSIONS
  The DTU TcI, which is mainly associated with acute cases of Chagas disease in the Amazon region, is also responsible for chronic infection in patients from a region in the State of Amazonas.
authors.forename: Rosa Amélia Gonçalves
authors.initials: RA
authors.lastname: Santana
authors.forename: Laylah Kelre Costa
authors.initials: LK
authors.lastname: Magalhães
authors.forename: Laise Kelman Costa
authors.initials: LK
authors.lastname: Magalhães
authors.forename: Suzane Ribeiro
authors.initials: SR
authors.lastname: Prestes
authors.forename: Marcel Gonçalves
authors.initials: MG
authors.lastname: Maciel
authors.forename: George Allan Villarouco
authors.initials: GA
authors.lastname: da Silva
authors.forename: Wuelton Marcelo
authors.initials: WM
authors.lastname: Monteiro
authors.forename: Felipe Rocha
authors.initials: FR
authors.lastname: de Brito
authors.forename: Leila Inês
authors.initials: LI
authors.lastname: de Aguiar Raposo Câmara Coelho
authors.forename: João Marcos
authors.initials: JM
authors.lastname: Barbosa-Ferreira
authors.forename: Jorge Augusto Oliveira
authors.initials: JA
authors.lastname: Guerra
authors.affiliation: Institute of Hygiene and Tropical Medicine (Instituto de Higiene e Medicina Tropical), New University of Lisbon (Universidade Nova de Lisboa), Lisbon, Portugal. HSilveira@ihmt.unl.pt.
authors.forename: Henrique
authors.initials: H
authors.lastname: Silveira
authors.forename: Maria
authors.initials: M
authors.lastname: das Graças Vale Barbosa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D001938:Brazil / Q000453:epidemiology; D014355:Chagas Disease / Q000097:blood / Q000453:epidemiology / Q000469:parasitology*; D002648:Child; D002908:Chronic Disease; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D005243:Feces / Q000469:parasitology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D050259:Genes, Mitochondrial; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D014224:Triatoma / Q000469:parasitology; D014349:Trypanosoma cruzi / Q000145:classification* / Q000235:genetics; D055815:Young Adult
chemical_list: D003576:Electron Transport Complex IV