title: The Chagas disease domestic transmission cycle in Guatemala: Parasite-vector switches and lack of mitochondrial co-diversification between Triatoma dimidiata and Trypanosoma cruzi subpopulations suggest non-vectorial parasite dispersal across the Motagua valley.
abstract: Parasites transmitted by insects must adapt to their vectors and reservoirs. Chagas disease, an American zoonosis caused by Trypanosoma cruzi, is transmitted by several species of triatomines. In Central America, Triatoma dimidiata is a widely dispersed vector found in sylvatic and domestic habitats, with distinct populations across the endemic region of Guatemala. Our aim was to test the strength of association between vector and parasite genetic divergence in domestic environments. Microsatellite (MS) loci were used to characterize parasites isolated from T. dimidiata (n=112) collected in domestic environments. Moderate genetic differentiation was observed between parasites north and south of the Motagua Valley, an ancient biogeographic barrier (FST 0.138, p=0.009). Slightly reduced genotypic diversity and increased heterozygosity in the north (Allelic richness (Ar)=1.00-6.05, FIS -0.03) compared to the south (Ar=1.47-6.30, FIS 0.022) suggest either a selective or demographic process during parasite dispersal. Based on parasite genotypes and geographic distribution, 15 vector specimens and their parasite isolates were selected for mitochondrial co-diversification analysis. Genetic variability and phylogenetic congruence were determined with mitochondrial DNA sequences (10 parasite maxicircle gene fragments and triatomine ND4+CYT b). A Mantel test as well as phylogenetic, network and principal coordinates analyses supported at least three T. dimidiata haplogroups separated by geographic distance across the Motagua Valley. Maxicircle sequences showed low T. cruzi genetic variability (π nucleotide diversity 0.00098) with no evidence of co-diversification with the vector, having multiple host switches across the valley. Sylvatic Didelphis marsupialis captured across the Motagua Valley were found to be infected with T. cruzi strains sharing MS genotypes with parasites isolated from domiciliated triatomines. The current parasite distribution in domestic environments can be explained by multiple parasite-host switches between vector populations and selection or bottleneck processes across the Motagua Valley, with a possible role for didelphids in domestic transmission.
authors.affiliation: Universidad del Valle de Guatemala, Centro de Estudios en Salud, 18 Avenida 11-95 Z. 15 VH III, Guatemala, Guatemala. Electronic address: pamelap@uvg.edu.gt.
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Pennington
authors.affiliation: London School of Hygiene & Tropical Medicine (University of London), Department of Infectious and Tropical Diseases, Keppel Street, London WC1E 7HT, UK.
authors.forename: Louisa Alexandra
authors.initials: LA
authors.lastname: Messenger
authors.affiliation: Universidad del Valle de Guatemala, Centro de Estudios en Salud, 18 Avenida 11-95 Z. 15 VH III, Guatemala, Guatemala.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Reina
authors.affiliation: Universidad del Valle de Guatemala, Centro de Estudios en Salud, 18 Avenida 11-95 Z. 15 VH III, Guatemala, Guatemala.
authors.forename: José G
authors.initials: JG
authors.lastname: Juárez
authors.affiliation: Centers for Disease Control and Prevention. Division of Parasitic Diseases and Malaria, 1600 Clifton Rd, Atlanta, GA 30333, USA.
authors.forename: Gena G
authors.initials: GG
authors.lastname: Lawrence
authors.affiliation: Centers for Disease Control and Prevention. Division of Parasitic Diseases and Malaria, 1600 Clifton Rd, Atlanta, GA 30333, USA.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Dotson
authors.affiliation: Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences,University of Wales, Bangor, Deiniol Road, Bangor, Gwynedd, LL57 2UW, UK.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Llewellyn
authors.affiliation: Universidad del Valle de Guatemala, Centro de Estudios en Salud, 18 Avenida 11-95 Z. 15 VH III, Guatemala, Guatemala. Electronic address: ccordon@ces.uvg.edu.gt.
authors.forename: Celia
authors.initials: C
authors.lastname: Cordón-Rosales
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000469:parasitology; D002489:Central America; D014355:Chagas Disease / Q000469:parasitology* / Q000635:transmission*; D004272:DNA, Mitochondrial / Q000235:genetics; D006166:Guatemala; D006790:Host-Parasite Interactions; D006801:Humans; D007303:Insect Vectors / Q000469:parasitology*; D010802:Phylogeny; D014224:Triatoma / Q000235:genetics* / Q000469:parasitology*; D014349:Trypanosoma cruzi / Q000235:genetics* / Q000469:parasitology*
chemical_list: D004272:DNA, Mitochondrial
keywords: Chagas disease; Cophylogeny; Phylogeography; Population genetics; Vector-borne disease