The extant T. cruzi population in Arequipa arose from a single, recent introduction.

Maximum clade credibility (MCC) tree shows that (A) all 123 T. cruzi isolated from bugs and domestic mammals in Arequipa form a monophyletic group with a single, recent common ancestor, indicative of a single immigration event in the recent past. Despite substantial genetic diversity among T. cruzi throughout South America, those collected in Arequipa show little diversity. (B) Three samples collected in Campo Florido and Naranjal, Peru and one sample from La Esperanza, Peru have nearly identical maxicircle sequences and form a monophyletic group. La Esperanza, Peru contains at least two distinct T. cruzi lineages, suggesting multiple independent introductions. (C) The only T. cruzi sample isolated from a human in Arequipa is distinct from all other samples from Arequipa, suggesting that this introduction has not established in the city. All tips represent a single sample except (A) (N = 123) and (B) (N = 4). All nodes have strong support (posterior probability≥0.99). Nodes are collapsed when the samples contained have nearly identical maxicircle sequences. Roman numerals signify DTU.