title: Oral transmission of Chagas disease: typing of Trypanosoma cruzi from five outbreaks occurred in Venezuela shows multiclonal and common infections in patients, vectors and reservoirs.
abstract: In Venezuela six episodes of oral transmission of Chagas disease (OChD) have been described, being the one reported in 2007 with a total of 103 people infected the largest worldwide. This work shows the use of three molecular markers (mini-exon gene and domains 24Sα and 18S of the ribosomal RNA) to characterize the infecting Trypanosoma cruzi strain of patients, reservoirs and vectors involved in five of the six OChD outbreaks. For this, 28 T. cruzi isolates were characterized by PCR, and the products of these reactions cloned and sequenced to reveal the existence of different TcI SL-IR genotypes. We also describe a new PCR assay able to discriminate between TcIb and TcId parasite populations. In summary, we have identified mostly parasites with the TcId haplotype and multiclonal populations with predominance of haplotype TcId (65.2%). Additionally, populations of haplotypes TcIb, TcIa and mixtures (TcId+TcIb, TcId+TcIa, TcIb+TcIa) are recurrent in samples obtained from children. The analysis of the SL-IR motif showed two clones depicting a different motif that could be an evidence for a possible hybrid haplotype between TcIa and TcIb (haplotype TcIa/Ib). Interestingly, in a single patient haplotype differences between T.cruzi isolates obtained pre and post-treatment were found. In conclusion, our findings show that in order to understand the pathogenic mechanisms involved in the orally acquired Chagas disease there is a need to join efforts to study T. cruzi haplotypes, their tissue tropisms and their susceptibility to chemoteraphy.
authors.affiliation: Sección de Inmunología, Instituto de Medicina Tropical, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela.
authors.forename: A
authors.initials: A
authors.lastname: Muñoz-Calderón
authors.forename: Z
authors.initials: Z
authors.lastname: Díaz-Bello
authors.forename: B
authors.initials: B
authors.lastname: Valladares
authors.forename: O
authors.initials: O
authors.lastname: Noya
authors.forename: M C
authors.initials: MC
authors.lastname: López
authors.forename: B
authors.initials: B
authors.lastname: Alarcón de Noya
authors.forename: M C
authors.initials: MC
authors.lastname: Thomas
mesh_terms: D000818:Animals; D001483:Base Sequence; D014355:Chagas Disease / Q000453:epidemiology* / Q000635:transmission*; D004196:Disease Outbreaks; D004197:Disease Reservoirs / Q000469:parasitology; D004199:Disease Vectors; D005091:Exons; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D018895:Microsatellite Repeats; D058889:Molecular Typing; D020038:RNA, Spliced Leader; D014349:Trypanosoma cruzi / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D014687:Venezuela / Q000453:epidemiology
chemical_list: D020038:RNA, Spliced Leader