Sex, Subdivision, and Domestic Dispersal of Trypanosoma cruzi Lineage I in Southern Ecuador

Abstract

BackgroundMolecular epidemiology at the community level has an important guiding role in zoonotic disease control programmes where genetic markers are suitably variable to unravel the dynamics of local transmission. We evaluated the molecular diversity of Trypanosoma cruzi, the etiological agent of Chagas disease, in southern Ecuador (Loja Province). This kinetoplastid parasite has traditionally been a paradigm for clonal population structure in pathogenic organisms. However, the presence of naturally occurring hybrids, mitochondrial introgression, and evidence of genetic exchange in the laboratory question this dogma.Methodology/Principal FindingsEighty-one parasite isolates from domiciliary, peridomiciliary, and sylvatic triatomines and mammals were genotyped across 10 variable microsatellite loci. Two discrete parasite populations were defined: one predominantly composed of isolates from domestic and peridomestic foci, and another predominantly composed of isolates from sylvatic foci. Spatial genetic variation was absent from the former, suggesting rapid parasite dispersal across our study area. Furthermore, linkage equilibrium between loci, Hardy-Weinberg allele frequencies at individual loci, and a lack of repeated genotypes are indicative of frequent genetic exchange among individuals in the domestic/peridomestic population.Conclusions/SignificanceThese data represent novel population-level evidence of an extant capacity for sex among natural cycles of T. cruzi transmission. As such they have dramatic implications for our understanding of the fundamental genetics of this parasite. Our data also elucidate local disease transmission, whereby passive anthropogenic domestic mammal and triatomine dispersal across our study area is likely to account for the rapid domestic/peridomestic spread of the parasite. Finally we discuss how this, and the observed subdivision between sympatric sylvatic and domestic/peridomestic foci, can inform efforts at Chagas disease control in Ecuador.

Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses?

“…A few studies have challenged an RD pattern within T. cruzi near-clades and are consistent with the hypothesis that recombination is frequent within TCI (Barnabé et al, 2013;Messenger et al, 2012;Ocaña-Mayorga et al, 2010) and TCII (de Paula Baptista et al, 2014). However, studies by Barnabé et al (2013) and Ocaña et al (2010) were based on limited samples (79 strains partitioned into six populations in the first one, 16 strains in the second one), and have to be confirmed by broader sets of data to eliminate a possible statistical type II error. In the study by Messenger et al (2012), evidence for recombination was based on discrepancies between trees designed from mitochondrial and nuclear genotypes.…”

“…The PCE model has been quoted 'artefactual', 'conceptually outdated', 'unnecessarily complicated' Llewellyn, 2014, 2015), and 'challenged' (Messenger et al, 2012;Messenger and Miles, 2015;Ocaña-Mayorga et al, 2010;Rougeron et al, 2010). However, a model can be considered outdated or challenged only when it has been clearly rejected, not the way it is misleadingly enunciated by its opponents, but rather, as it is presented in the very terms (as mentioned earlier) of its authors.…”

Ecological host fitting of Trypanosoma cruzi TcI in Bolivia: mosaic population structure, hybridization and a role for humans in Andean parasite dispersal

“…1996), between domestic/peri‐domestic populations in Ecuador (Ocaña‐Mayorga et al . 2010) and within an endemic focus in Colombia (Ramírez et al . 2012) suggests that intensive local sampling of transmission cycles is an effective strategy to detect recombination.…”

“…2009a; Ocaña‐Mayorga et al . 2010; Lima et al . 2014), and divergent, but genetically homogeneous, strains isolated from human infections (Llewellyn et al .…”

Microsatellite and Mini-Exon Analysis of Mexican Human DTU ITrypanosoma cruziStrains and Their Susceptibility to Nifurtimox and Benznidazole

“…Subgroups of TcI have also been reported, using mini-exon gene sequences and microsatellite analysis (Macedo et al 2001, Falla et al 2009, Llewelyn et al 2009, Ocañ a-Mayorga et al 2010, Barnabé et al 2011). …”