title: Chagas' disease in Aboriginal and Creole communities from the Gran Chaco Region of Argentina: Seroprevalence and molecular parasitological characterization.
abstract: Most indigenous ethnias from Northern Argentina live in rural areas of "the Gran Chaco" region, where Trypanosoma cruzi is endemic. Serological and parasitological features have been poorly characterized in Aboriginal populations and scarce information exist regarding relevant T. cruzi discrete typing units (DTU) and parasitic loads. This study was focused to characterize T. cruzi infection in Qom, Mocoit, Pit'laxá and Wichi ethnias (N=604) and Creole communities (N=257) inhabiting rural villages from two highly endemic provinces of the Argentinean Gran Chaco. DNA extracted using Hexadecyltrimethyl Ammonium Bromide reagent from peripheral blood samples was used for conventional PCR targeted to parasite kinetoplastid DNA (kDNA) and identification of DTUs using nuclear genomic markers. In kDNA-PCR positive samples from three rural Aboriginal communities of "Monte Impenetrable Chaqueño", minicircle signatures were characterized by Low stringency single primer-PCR and parasitic loads calculated using Real-Time PCR. Seroprevalence was higher in Aboriginal (47.98%) than in Creole (27.23%) rural communities (Chi square, p=4.e(-8)). A low seroprevalence (4.3%) was detected in a Qom settlement at the suburbs of Resistencia city (Fisher Exact test, p=2.e(-21)).The kDNA-PCR positivity was 42.15% in Aboriginal communities and 65.71% in Creole populations (Chi square, p=5.e(-4)). Among Aboriginal communities kDNA-PCR positivity was heterogeneous (Chi square, p=1.e(-4)). Highest kDNA-PCR positivity (79%) was detected in the Qom community of Colonia Aborigen and the lowest PCR positivity in two different surveys at the Wichi community of Misión Nueva Pompeya (33.3% in 2010 and 20.8% in 2014). TcV (or TcII/V/VI) was predominant in both Aboriginal and Creole communities, in agreement with DTU distribution reported for the region. Besides, two subjects were infected with TcVI, one with TcI and four presented mixed infections of TcV plus TcII/VI. Most minicircle signatures clustered according to their original localities, but in a few cases, signatures from one locality clustered with signatures from other village, suggesting circulation of the same strains in the area. Parasitic loads ranged from undetectable to around 50 parasite equivalents/mL, showing higher values than those generally observed in chronic Chagas disease patients living in urban centers of Argentina. Our findings reveal the persistence of high levels of infection in these neglected populations.
authors.affiliation: Area de Biología Molecular, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Argentina; Cátedra de Medicina III, Area Infectología, Facultad de Medicina, Universidad Nacional del Nordeste, Corrientes, Argentina.
authors.forename: R H
authors.initials: RH
authors.lastname: Lucero
authors.affiliation: Area de Biología Molecular, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Argentina.
authors.forename: B L
authors.initials: BL
authors.lastname: Brusés
authors.affiliation: Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular Dr Héctor Torres (INGEBI-CONICET), Buenos Aires, Argentina.
authors.forename: C I
authors.initials: CI
authors.lastname: Cura
authors.affiliation: Area de Biología Molecular, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Argentina.
authors.forename: L B
authors.initials: LB
authors.lastname: Formichelli
authors.affiliation: Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular Dr Héctor Torres (INGEBI-CONICET), Buenos Aires, Argentina.
authors.forename: N
authors.initials: N
authors.lastname: Juiz
authors.affiliation: Area de Biología Molecular, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Argentina.
authors.forename: G J
authors.initials: GJ
authors.lastname: Fernández
authors.affiliation: Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular Dr Héctor Torres (INGEBI-CONICET), Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Bisio
authors.affiliation: Laboratorio de Aplicaciones Moleculares, Cátedra de Microbiología, Parasitología e Inmunología de la Facultad de Medicina de la UNNE, Resistencia, Argentina.
authors.forename: G D
authors.initials: GD
authors.lastname: Deluca
authors.affiliation: Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular Dr Héctor Torres (INGEBI-CONICET), Buenos Aires, Argentina.
authors.forename: S
authors.initials: S
authors.lastname: Besuschio
authors.affiliation: Consultorio de Chagas, Facultad de Medicina, Universidad Nacional del Nordeste, Corrientes, Argentina.
authors.forename: D O
authors.initials: DO
authors.lastname: Hernández
authors.affiliation: Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular Dr Héctor Torres (INGEBI-CONICET), Buenos Aires, Argentina. Electronic address: schijman@dna.uba.ar.
authors.forename: A G
authors.initials: AG
authors.lastname: Schijman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001118:Argentina / Q000453:epidemiology; D014355:Chagas Disease / Q000453:epidemiology* / Q000208:ethnology / Q000469:parasitology; D002648:Child; D002675:Child, Preschool; D018105:DNA, Kinetoplast / Q000235:genetics*; D019353:Endemic Diseases; D006801:Humans; D007199:Indians, South American; D007223:Infant; D008875:Middle Aged; D059208:Parasite Load; D010802:Phylogeny; D012424:Rural Population; D016036:Seroepidemiologic Studies; D014349:Trypanosoma cruzi / Q000145:classification / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D035862:Vulnerable Populations
chemical_list: D018105:DNA, Kinetoplast
keywords: Aboriginal population; CTAB reagent, polymerase chain reaction; Chagas disease; Trypanosoma cruzi, discrete typing unit; parasitic load