North American import? Charting the origins of an enigmatic Trypanosoma cruzi domestic genotype

Abstract

BackgroundTrypanosoma cruzi, the agent of Chagas disease, is currently recognized as a complex of six lineages or Discrete Typing Units (DTU): TcI-TcVI. Recent studies have identified a divergent group within TcI - TcIDOM. TcIDOM. is associated with a significant proportion of human TcI infections in South America, largely absent from local wild mammals and vectors, yet closely related to sylvatic strains in North/Central America. Our aim was to examine hypotheses describing the origin of the TcIDOM genotype. We propose two possible scenarios: an emergence of TcIDOM in northern South America as a sister group of North American strain progenitors and dispersal among domestic transmission cycles, or an origin in North America, prior to dispersal back into South American domestic cycles. To provide further insight we undertook high resolution nuclear and mitochondrial genotyping of multiple Central American strains (from areas of México and Guatemala) and included them in an analysis with other published data.FindingsMitochondrial sequence and nuclear microsatellite data revealed a cline in genetic diversity across isolates grouped into three populations: South America, North/Central America and TcIDOM. As such, greatest diversity was observed in South America (Ar = 4.851, π = 0.00712) and lowest in TcIDOM (Ar = 1.813, π = 0.00071). Nuclear genetic clustering (genetic distance based) analyses suggest that TcIDOM is nested within the North/Central American clade.ConclusionsDeclining genetic diversity across the populations, and corresponding hierarchical clustering suggest that emergence of this important human genotype most likely occurred in North/Central America before moving southwards. These data are consistent with early patterns of human dispersal into South America.

Circulation of Tc Ia discrete type unit Trypanosoma cruzi in Yucatan Mexico

“…Our findings are different than those observed in Colombia where Tc Ia (recently named Tc I DOM) is preferentially associated with R. prolixus and humans in domestic cycles (Falla et al 2009;Zumaya-Estrada et al 2012), whereas in the Yucatan Peninsula T. dimidiata is rather a visiting vector than a domiciliated participating more in peridomestic and sylvatic cycles. The human would be an accidental host in this cycle.…”

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

“…2012; Zumaya‐Estrada et al . 2012). However, the genetic determinants that drive natural T. cruzi diversification are largely unknown.…”

Prehistoric earth oven facilities and the pathoecology of Chagas disease in the Lower Pecos Canyonlands

“…Recent molecular analysis of six lineages of Chagas disease, and a divergent group, modifies even more our perspective on this disease (Zumaya-Estrada et al, 2012). This analysis, and accompanying molecular clock, suggests that the earliest migrations of humans encountered Chagas disease in North America.…”