Alliances for Chagas elimination in Central America

Chagas disease is mainly transmitted by triatomine insect vectors that feed on vertebrate blood. The disease has complex domiciliary infestation patterns and parasite transmission dynamics, influenced by biological, ecological, and socioeconomic factors. In this context, feeding patterns have been used to understand vector movement and transmission risk. Recently, a new technique using Liquid chromatography tandem mass spectrometry (LC-MS/MS) targeting hemoglobin peptides has showed excellent results for understanding triatomines’ feeding patterns. The aim of this study was to further develop the automated computational analysis pipeline for peptide sequence taxonomic identification, enhancing the ability to analyze large datasets.

Triatoma dimidiata is the main vector of Chagas disease in southern Mexico, Central America and northern South America. As a native vector, it moves readily among domestic, peri‑domestic and sylvatic environments, making it difficult to control only using insecticide as this requires regular application, and re-infestation frequently occurs. Other social innovation alternatives such as those based on Ecohealth principles can be used to tackle the dynamics of the disease in an integral way. We asked whether an Ecohealth intervention, implemented beginning in 2001 in a highly infested village, 41.8%, in southeastern Guatemala, was sustainable in the long term. This intervention included initial insecticide treatments, followed by making low-cost house improvements to eliminate transmission risk factors such as repairing cracked walls, covering dirt floors with a cement-like substance and moving domestic animals outside. We assessed the long-term sustainability through entomological and house condition surveys, as well as an analysis of community satisfaction. The Ecohealth approach is a low-cost, sustainable approach for the long-term control of vector-borne Chagas disease. We recommend this approach including ongoing community monitoring and institutional response for the long-term, integrated control of Chagas disease.

Widespread application of insecticide remains the primary form of control for Chagas disease in Central America, despite only temporarily reducing domestic levels of the endemic vector Triatoma dimidiata and having little long-term impact. Recently, an approach emphasizing community feedback and housing improvements has been shown to yield lasting results. However, the additional resources and personnel required by such an intervention likely hinders its widespread adoption. One solution to this problem would be to target only a subset of houses in a community while still eliminating enough infestations to interrupt disease transfer. Here we develop a sequential sampling framework that adapts to information specific to a community as more houses are visited, thereby allowing us to efficiently find homes with domiciliary vectors while minimizing sampling bias. The method fits Bayesian geostatistical models to make spatially informed predictions, while gradually transitioning from prioritizing houses based on prediction uncertainty to targeting houses with a high risk of infestation. A key feature of the method is the use of a single exploration parameter, α, to control the rate of transition between these two design targets. In a simulation study using empirical data from five villages in southeastern Guatemala, we test our method using a range of values for α, and find it can consistently select fewer homes than random sampling, while still bringing the village infestation rate below a given threshold. We further find that when additional socioeconomic information is available, much larger savings are possible, but that meeting the target infestation rate is less consistent, particularly among the less exploratory strategies. Our results suggest new options for implementing long-term T. dimidiata control.