Microgeographical analysis of genetic structure and reinfestation dynamics of Triatoma infestans populations in northern Argentina.

MARCET PL, MORA MS, CUTRERA AP, GURTLER RE, KITRON U, DOTSON E

Washington, USA

Congreso; 58th Annual Meeting of the American Society of Tropical Medicine and Hygiene; 2009

The control of T. 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 phylogeographic 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 780 T. infestans collected in houses of rural villages in Santiago del Estero province, northern Argentina during pre and post spraying surveys using 10 microsatellite loci. Genic and genotype diversity were assessed for populations at each capture site, pair-wise comparisons between sites and bayesian based individual assignment were performed. Significant levels of substructure within villages and capture sites were detected. Migration among capture sites and colonization from multiple sources are likely causes of the genetic structure of T. infestans populations detected in these communities. A significant impact of vector control actions was reflected in the genetic structure of villages under different control pressure. Taking into account the total genetic pool available from two baseline pre-spraying studies, results showed that most bugs captured post-spraying could have originated from spraying survivors from within each community, and putative source were identified. Thus, these results provide support to the hypothesis of reinfestation by local survivors that actively disperse to neighboring sites. In addition, evidence of gene-flow among villages reinforces the need of establishing vector control efforts beyond the village level.