Land cover change as a determinant of house infestation with Chagas disease vectors in the Argentine Chaco

GASPE MS; ARGIBAY HD; RODRIGUEZ-PLANES LI; GÜRTLER RE

Nueva Orleans

Congreso; ESA Annual Meeting; 2018

The transmission of vector-borne pathogens requires the spatio-temporal coincidence of pathogens, hosts and vectors. Understanding the main determinants of vector occurrence and persistence may improve our ability to predict infestation risk and prevent pathogen transmission. Chagas disease is caused by Trypanosoma cruzi, which is transmitted between mammalian and human hosts through insects (Triatominae) in the Americas. The main vector, domestic Triatoma infestans, and a secondary peridomestic or sylvatic species (Triatoma sordida) live in sympatry and are able to transmit T. cruzi in rural houses from the Gran Chaco ecoregion. Forest fragments near houses may harbor triatominae colonies, and regional land-use change may increase or accelerate their arrival to houses. The aim of this work was to analyze how land cover and land cover change over time is related to house infestation risk. In total, 41% of the pixels shifted from forest fragments to short-disturbance or no vegetation over the 8-yr period. Humid forest, short-disturbance and no vegetation were the most relevant classes for house context discrimination. Vegetation near the houses at all spatial scales was intimately related to the prespraying pattern of house infestation with T. sordida but not T. infestans, which lacks local sylvatic foci. No-vegetation pixels within 100m radius around houses were associated with a 2.5-fold higher probability of post-spraying house infestation with either species. The frequency of pixels classified as forests before insecticide spraying and as short-disturbance or no vegetation at 8-yr postspraying significantly increases the probability of house reinfestation with T. sordida but not T. infestans. Our findings suggest that the loss of forest cover is associated with an increased risk of triatomine occurrence, especially for T. sordida, a non-target species with sylvatic foci. T. infestans, primary vector and regional elimination program target, was only associated with no-vegetation pixels. This may be relevant to direct vector control efforts to houses with higher infestation risk: hotspots of forest loss. Whether habitat loss or the higher temperature related to barren soil facilitate the invasion and successful establishment of triatomines remains unknown and deserves further investigation.