title: The role of sigmodontine rodents as sylvatic hosts of Trypanosoma cruzi in the Argentinean Chaco.
abstract: The role of rodents in the sylvatic transmission of Trypanosoma cruzi has seldom been investigated using parasitological and molecular methods. We assessed the occurrence of T. cruzi in wild small rodents from Pampa del Indio, in the Argentinean Chaco, and identified the taxonomic status of positive rodents by sequencing a fragment of cytochrome b gene (cytb) and performing BLAST searches and phylogenetic analyses. A total of 176 Sigmodontinae rodents was captured in six surveys using 5425 trap-nights in a wide range of sylvatic habitats between 2009 and 2011. Host infection was determined by xenodiagnosis and by polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR) from blood samples. None of the 176 rodents examined was xenodiagnosis-positive. The prevalence of infection determined by kDNA-PCR from blood samples was 16.2% (95% confidence interval, 10.1-21.9%). Half of the infections detected by kDNA-PCR were confirmed by nuclear satellite DNA-PCR or by kDNA-PCR of the rectal contents of xenodiagnostic bugs. The 24 positive specimens were assigned to eight species, providing the first records of T. cruzi in Akodon montensis, Akodon toba, Graomys chacoensis, and Oligoryzomys chacoensis. The occurrence of T. cruzi infection in Oligoryzomys nigripes, Calomys callosus, Necromys lasiurus and Oecomys sp. (most probably Oecomys mamorae) from the Gran Chaco is also reported for the first time. Although sigmodontine rodents were frequently infected, the intensity of bug rectal infection with T. cruzi was below the detection limit of xenodiagnosis (subpatent infectiousness to bugs), indicating they had a low reservoir host competence.
authors.affiliation: Laboratorio de Eco-Epidemiología, Departamento de Ecología, Genética y Evolución, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina; Instituto de Ecología, Genética y Evolución (IEGEBA), CONICET, Argentina.
authors.forename: M Marcela
authors.initials: MM
authors.lastname: Orozco
authors.affiliation: Laboratorio de Eco-Epidemiología, Departamento de Ecología, Genética y Evolución, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina; Instituto de Ecología, Genética y Evolución (IEGEBA), CONICET, Argentina.
authors.forename: Romina V
authors.initials: RV
authors.lastname: Piccinali
authors.affiliation: Instituto de Investigaciones Marinas y Costeras (IIMyC, CONICET), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, 7600, Mar del Plata, Argentina.
authors.forename: Matías S
authors.initials: MS
authors.lastname: Mora
authors.affiliation: Laboratorio de Eco-Epidemiología, Departamento de Ecología, Genética y Evolución, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina; Instituto de Ecología, Genética y Evolución (IEGEBA), CONICET, Argentina.
authors.forename: Gustavo F
authors.initials: GF
authors.lastname: Enriquez
authors.affiliation: Laboratorio de Eco-Epidemiología, Departamento de Ecología, Genética y Evolución, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina; Instituto de Ecología, Genética y Evolución (IEGEBA), CONICET, Argentina.
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Cardinal
authors.affiliation: Laboratorio de Eco-Epidemiología, Departamento de Ecología, Genética y Evolución, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina; Instituto de Ecología, Genética y Evolución (IEGEBA), CONICET, Argentina. Electronic address: gurtler@ege.fcen.uba.ar.
authors.forename: Ricardo E
authors.initials: RE
authors.lastname: Gürtler
mesh_terms: D000818:Animals; D001118:Argentina / Q000453:epidemiology; D014355:Chagas Disease / Q000453:epidemiology / Q000635:transmission*; D004197:Disease Reservoirs / Q000469:parasitology*; D016205:Sigmodontinae / Q000469:parasitology*; D014349:Trypanosoma cruzi / Q000302:isolation & purification*
keywords: Molecular diagnosis; Molecular identification; Reservoir competence; Rodents; Sigmodontinae; Trypanosoma cruzi