CONICET | Buscador de Institutos y Recursos Humanos

Trypanosoma cruzi infection affects an estimated 230,000 people in Ecuador. Recent reports indicate limited effectiveness of insecticidebased vector control interventions, due to re-infestation by sylvatic triatomines. Previous studies demonstrated that the lineage I (TcI) of T. cruzi is the predominant lineage circulating in Loja (Southern Andes) and Manabi (Central Coastal) provinces. Furthermore, in southern Ecuador(Loja province) microsatellite analyses of TcI isolates showed two main parasite populations exist: one related with domestic and peridomestic environments and a second one related with sylvatic environments. The aim of this study was to evaluate TcI isolate divergence within and among Loja and Manabí using Multi Locus Sequence Typing (MLST). We sampled vectors and mammals and a wide geographic area within each province. Our results corroborate that the presence of two different parasite populations in Ecuador, according to habitat: In Loja province, the previous separation in two populations (domestic/peridomestic and sylvatic) was confirmed. In Manabí province, this tendency was also seen, where the sylvatic population was separated from the peridomesic population. However, in both cases, limited genetic flow was evidenced. Interestingly sylvatic samples of both provinces cluster together, suggesting genetic flow among sylvatic populations, while genetic separation was evident between domestic/peridomestic populations of both provinces. These results suggest that similar transmission dynamics are taking place in both provinces where albeit at different rates, there is limited genetic flow between sylvatic and domestic/peridomestic T. cruzi populations within a small geographical area. Therefore, control strategies need to be adapted to the intrinsic characteristics of a small geographic scale.