title: Detection of Trypanosoma cruzi in untreated chronic chagasic patients is improved by using three parasitological methods simultaneously.
abstract: OBJECTIVE
  This study compared three parasitological methods applied simultaneously in individuals with untreated chronic Chagas' disease in order to determine their individual and combined performances.
  
  
  METHODS
  From a total of 100 chronic chagasic patients from endemic areas of Chile, with informed consent, we extracted 2 mL of peripheral venous blood for PCR (PCR-B) and applied two xenodiagnosis (XD) boxes with seven uninfected Triatoma infestans nymphs each for microscopic examination and PCR of faecal samples of the triatomines fed on each patient (PCR-XD). The PCR-B and PCR-XD reactions were performed with oligonucleotides 121 and 122, which anneal to the four constant regions of the minicircles of Trypanosoma cruzi kinetoplasts. The 330 bp PCR product was analysed by electrophoresis in a 2% agarose gel and visualized by staining with ethidium bromide.
  
  
  RESULTS
  PCR-B detected T. cruzi in 58% of the cases, while PCR-XD proved to be more sensitive than XD (67% versus 14%, respectively) (P = 0.0001). There was no difference between the detection power of PCR-B and PCR-XD (P = 0.222). The percentage detected as positive was much greater when the three tests were considered (84%) (P = 0.00001).
  
  
  CONCLUSIONS
  The simultaneous application of more than one technique for the parasitological diagnosis of Chagas' disease in untreated individuals increases the possibility of detection of T. cruzi.
authors.affiliation: Laboratorio Parasitología Básico Clínico, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. izulanta@med.uchile.cl
authors.forename: Inés
authors.initials: I
authors.lastname: Zulantay
authors.forename: Werner
authors.initials: W
authors.lastname: Apt
authors.forename: Claudio
authors.initials: C
authors.lastname: Valencia
authors.forename: Alberto
authors.initials: A
authors.lastname: Torres
authors.forename: Miguel
authors.initials: M
authors.lastname: Saavedra
authors.forename: Jorge
authors.initials: J
authors.lastname: Rodríguez
authors.forename: Lea
authors.initials: L
authors.lastname: Sandoval
authors.forename: Gabriela
authors.initials: G
authors.lastname: Martínez
authors.forename: Patricio
authors.initials: P
authors.lastname: Thieme
authors.forename: Eduardo
authors.initials: E
authors.lastname: Sepúlveda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D014355:Chagas Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology; D002677:Chile; D005243:Feces / Q000469:parasitology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010274:Parasitology / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods; D014224:Triatoma / Q000469:parasitology; D014349:Trypanosoma cruzi / Q000302:isolation & purification*; D020525:Xenodiagnosis / Q000379:methods