Sources of reinfestation by Triatoma infestans following insecticide spraying in neighboring communities in northwestern Argentina.

CECERE MC, VAZQUEZ-PROKOPEC GM, GÜRTLER RE, KITRON U.

Washington DC, USA

Congreso; Emerging Infectious Diseases.; 2005

The spatio-temporal reinfestation patterns by Triatoma infestans following a blanket insecticide spraying in two proximate rural communities in northwestern Argentina during 1993-1997 were analyzed using GIS, satellite imagery, and spatial statistics. The two communities are surrounded by neighboring communities with different history of infestation and insecticide spraying, and the effects of external, residual and primary sources on the reinfestation pattern were evaluated. Using retrospective data for all domestic and peridomestic sites during 5 years, epicenters of infestation, spatial clustering of T. infestans abundance around sources of reinfestation and the range of distances over which such reinfestation occurred were determined. The reinfestation process in a group of communities following residual insecticide spraying was shown to depend not only on the primary sources but also on external sources, with surrounding communities serving as sources of reinfestation. Successful control at the meso-scale level and the reduction of the reinfestation risk, require that all communities and isolated sites within 1500 m of the target community be treated. In addition, during the surveillance phase spraying of all sites within 400 m of new foci will reduce the process of reinfestation. The degree of interactions between communities and the range of of T. infestans dispersal distance need to be in a spatial model  of   reinfestation dynamics.