Urbanisation, risk stratification and house infestation with a major vector of Chagas disease in an endemic municipality of the Argentine Chaco

María Sol Gaspe,Ricardo Esteban Gürtler,Natalia Paula Macchiaverna,Gustavo Fabián Enriquez,Marta Victoria Cardinal,Lucía Inés Rodríguez-Planes,María Del Pilar Fernández

doi:10.1186/s13071-020-04182-3

Abstract

BackgroundThe occurrence of the major vectors of Chagas disease has historically been linked to poor rural housing, but urban or peri-urban infestations are increasingly being reported. We evaluated a simple risk index to detect houses infested with Triatoma infestans and tested whether house infestation and vector abundance increased across the urban-to-rural gradient in Avia Terai, an endemic municipality of the Argentine Chaco; whether the association between infestation and selected ecological determinants varied across the gradient; and whether urban and peri-urban infestations were associated with population settlement history.MethodsWe conducted a screening survey of house infestation in 2296 urban, peri-urban and rural dwellings to identify high-risk houses based on a simple index, and then searched for triatomines in all high-risk houses and in a systematic sample of low-risk houses.ResultsThe risk index had maximum sensitivity and negative predictive value, and low specificity. The combined number of infested houses in peri-urban and urban areas equalled that in rural areas. House infestation prevalence was 4.5%, 22.7% and 42.4% across the gradient, and paralleled the increasing trend in the frequency of domestic animals and peridomestic structures. Multiple logistic regression analysis showed that house infestation was positively and significantly associated with the availability of poultry and bug refuges in walls, and was negatively associated with domestic insecticide use. Several pieces of evidence, including absence of spatial aggregation of house infestation, support that T. infestans has been a long-established occupant of urban, peri-urban and rural settings in Avia Terai.ConclusionsAn integrated vector management strategy targeting chicken coops and good husbandry practices may provide more cost-effective returns to insecticide-based vector elimination efforts.

Highlights

The occurrence of the major vectors of Chagas disease has historically been linked to poor rural hous‐ ing, but urban or peri-urban infestations are increasingly being reported
Average bug abundance was greater in rural areas, but when the total collected is considered at the aggregate level, the relative magnitude of urban or peri-urban versus rural setting was more balanced
Triatomine control operations in rural areas traditionally follow the rules of continuity and contiguity, and seek to achieve full coverage of house units depending on village-level house infestation rates

Summary

Introduction

The occurrence of the major vectors of Chagas disease has historically been linked to poor rural hous‐ ing, but urban or peri-urban infestations are increasingly being reported. The global urbanisation trend is expected to continue during the decades [1] and has major implications for human health, in low- and middle-income countries where unplanned urbanisation has led to impoverished settlements with increased transmission of infectious diseases [2]. Most of the regions undergoing fast urbanisation overlap with high-risk areas of neglected tropical diseases (NTDs) [3]. This changing environment led to the (re)emergence of many NTDs which may become more intense in the near future [4]. Multidisciplinary research on transmission risk factors in urban settings is essential for evidence-based policy development and decision making [5]

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Conclusion