Spatial patterns of community reinfestation by Triatoma guasayana (Heteroptera: Reduviidae) in rural northwestern Argentina

VAZQUEZ-PROKOPEC GM, CECERE MC, CANALE DM1, GÜRTLER RE, KITRON U

Valencia-España

Congreso; 10. IX European Multicolloquium of Parasitology.; 2004

Triatoma guasayana is a potential substitute for Triatoma infestans as a vector of Trypanosoma cruzi, the causal agent of Chagas disease, in the Chaco region of Argentina and Bolivia. However, up to now T. guasayana is not a target species of control actions. The spatial distribution of T. guasayana in the rural community of Amamá in northern Argentina over the 10 years that followed a blanket spraying with deltamethrin in October 1992 is described and analyzed using very high spatial resolution satellite imagery (1-4 m2), Geographic Information Systems (GIS) and spatial statistics. Site-specific domestic and peridomestic reinfestation by triatomine bugs were monitored by various methods semi annually from October 1993 to October 2002. The reinfestation by T. guasayana started with the finding of only adult bugs in a few domestic and peridomestic ecotopes. In both the southern and northern extremes of Amamá overall bug abundance was significantly clustered and predominantly peridomestic. The identified source of reinfestation in the northern cluster was a colony in a wood pile, whereas no potential peridomestic source was found for the southern cluster. Houses closer to the edges of the community were invaded significantly more by flight-dispersing T. guasayana bugs. Active dispersal from the hypothesized source and from the surrounding sylvatic environment, and passive transport of bugs into and from wood piles appear to be the most likely mechanisms underlying the observed spatial pattern of T. guasayana. The absence of persistent domestic colonizations indicates that to date there is no increasing trend toward domesticity of T. guasayana in the study area. The clustering zones can be considered high risk areas where T. guasayana invasion from the sylvatic environment is expected to be higher and in which the introduction of sylvatic T. cruzi is more likely to occur.