Statistical phylogeography of Chagas disease vector Triatoma infestans: Testing biogeographic hypotheses of dispersal

Chagas disease is one of the most important vector-borne diseases in Latin America. The disease, caused by the flagellate protozoan Trypanosoma cruzi, is commonly transmitted to humans by Triatoma infestans in South America. Using mitochondrial DNA sequences, we assessed alternative biogeographic scenarios of dispersal of T. infestans using coalescence simulations. We also assessed phylogeographic structure and spatial genetics of T. infestans in Chile. Two major routes of dispersal in southern South America were supported including a dual-origin of T. infestans in Chile. Phylogeographic analyses identified two primary clades with Chilean haplotypes partitioned into either a northern cluster with Peruvian and Bolivian haplotypes or a north-central cluster with Argentinean and Uruguayan haplotypes. The north-central clade is further divided into two subgroups. Domestic and sylvatic T. infestans in central Chile were not segregated in the phylogeographic reconstruction. Spatial genetic analyses show higher distances in northern Chile, congruent with the presence of two divergent lineages of T. infestans. Phylogenetic evidence does not unequivocally support the hypothesized Bolivian origin of T. infestans, so we discuss alternative scenarios.

Research highlights▶ Two major routes of dispersal are supported for T. infestans in South America. ▶ Andean and non-Andean lineages of T. infestans colonized Chile. ▶ Sylvatic T. infestans in Chile may be the result of colonization from Argentina. ▶ Bolivia is not unequivocally supported as the center of origin of T. infestans. ▶ Earliest dispersal events for T. infestans in South America were not human-mediated.