Factors Affecting Infestation by Triatoma infestans in a Rural Area of the Humid Chaco in Argentina: A Multi- Model Inference Approach

JUAN M. GUREVITZ; LEONARDO A. CEBALLOS; MARÍA SOL GASPE; JULIÁN A. ALVARADO OTEGUI

PLOS NEGLECTED TROPICAL DISEASES

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2011 vol. 5

1935-2735

AbstractBackground: Transmission of Trypanosoma cruzi by Triatoma infestans remains a major public health problem in the GranChaco ecoregion, where understanding of the determinants of house infestation is limited. We conducted a cross-sectionalstudy to model factors affecting bug presence and abundance at sites within house compounds in a well-defined rural areain the humid Argentine Chaco.Methodology/Principal Findings: Triatoma infestans bugs were found in 45.9% of 327 inhabited house compounds but onlyin 7.4% of the 2,584 sites inspected systematically on these compounds, even though the last insecticide spraying campaignwas conducted 12 years before. Infested sites were significantly aggregated at distances of 0.8?2.5 km. The most frequentlyinfested ecotopes were domiciles, kitchens, storerooms, chicken coops and nests; corrals were rarely infested. Domiciles withmud walls and roofs of thatch or corrugated tarred cardboard weremore often infested (32.2%) than domiciles with brick-andcementwalls and corrugated metal-sheet roofs (15.1%). A multi-model inference approach using Akaike?s information criterionwas applied to assess the relative importance of each variable by running all possible (17,406) models resulting from allcombinations of variables. Availability of refuges for bugs, construction with tarred cardboard, and host abundance (humans,dogs, cats, and poultry) per site were positively associated with infestation and abundance, whereas reported insecticide useshowed a negative association. Ethnic background (Creole or Toba) adjusted for other factors showed little or no association.Conclusions/Significance: Promotion and effective implementation of housing improvement (including key peridomesticstructures) combined with appropriate insecticide use and host management practices are needed to eliminate infestations.Fewer refuges are likely to result in fewer residual foci after insecticide spraying, and will facilitate community-based vectorsurveillance. A more integrated perspective that considers simultaneously social, economic and biological processes at localand regional scales is needed to attain effective, sustainable vector and disease control.