Microgeographical analysis of genetic structure in Triatoma infestans populations from northern Argentina

MARCET PL, CUTRERA AP, JONES L, GURTLER RE, KITRON U Y DOTSON EM

Philadelphia, Pennsylvania USA

Congreso; 56th Annual Meeting of the American Society of Tropical Medicine and Hygiene; 2007

American Society of Tropical Medicine and Hygiene

The control of Triatoma infestans, the main vector of Chagas disease in South America, has had limited success in the Gran Chaco region due to high recolonization rates. A better understanding of the genetic structure, dispersal dynamics and phylogeographical relationships among T. infestans populations is needed in order to determine the source of reinfesting bugs and help design improved vector control strategies. We conducted a micro-geographical population structure study, analyzing the multilocus genotype of six microsatellites, from 337 T. infestans collected in 21 houses of 11 rural villages in Santiago del Estero province, northern Argentina. Genic and genotype diversity were assessed for populations at each capture site and pair-wise comparisons between sites were performed. Significant differences were detected among population pairs, among and within villages, and sub-structure was detected even within a capture site. The genetic differentiation among sample pairs was not consistent with a model of isolation by distance. The absence of significantly differentiated population pairs within a village, confirmed the occurrence of gene-flow by active migration, whereas events of local isolation were also detected. Reinfestation from independent sources might have occurred simultaneously in a village, and migration from different sources can explain the admixed origins populations established at a single site. Genetic structure of T. infestans populations varied among villages, which confirms differences in population history and dispersion dynamics reported previously for these neighboring villages. Evidence of gene-flow occurrence among villages reinforces the need of establishing vector control efforts beyond the village level.