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Risk factors of domiciliary infestation by triatomines

Because the disease is transmitted within human dwellings, many studies have examined the types of building that facilitate the development of triatomine colonies. However, an approach based on identifying risk factors for intradomiciliary infestation revealed the human activities that play a role in the disease’s epidemiological cycle. The results of these studies clearly showed that infestation is multifactorial and differs by region. Increasingly, it appears that the manner in which society and individuals position themselves and act against the disease and the vectors is crucial.82 Several studies found a strong association of disease prevalence with the type of construction, the materials used for walls and roofs, and the conditions of the materials. These factors facilitate triatomine colonizations inside a house, but other factors play a large role, including limited knowledge about the disease, socioeconomic status, crowded rooms, cleanliness (household hygiene), conviviality, and household pets. , For example, intervention by the inhabitants themselves through better household hygiene and housing construction would have the advantage of reducing the risk of infestation by triatomines for a longer duration than the standard intervention using insecticides.89 In the same way, the construction of an antitriatomine house model was developed in the province of Loja, involving the local population in the construction of houses.90

In addition, the peridomestic space is often a source of domestic infestation. The vectors may colonize several structures primarily related to domestic animals, but different vector species may colonize different structures. In rural localities in the state of Ceara, Brazil, T. brasiliensis primarily colonized brick piles and roofing tiles, T. pseudomaculata preferred wood poles and woodpiles, and R. nasutus was mainly found in roofing straw.91 Also, studies based on multivariate logistic regression analysis can rationally identify, among different structural and management factors, those that are associated with the infestation with triatomines.92-94 In a rural community in western Mexico, peridomestic infestation risks by T. longipennis and T. barberi (evaluated with multivariate logistic regression analysis) were related to the density of permanent and temporal structures but not with domestic animals because the main food source of triatomines was Rattus rattus.4995 In Guatemala, the persistence of T. dimidiata was associated with the conservation of habitats for dogs, chickens, and rodents.96 In the home, residents must rely on management changes to limit the infestation of triatomines in peridomestic areas. In other cases, attention must be paid to the immediate vegetation. For example, T. guasayana is a semisylvatic species that invades peridomestic sites in rural northwestern Argentina, and its spatial distribution is related to the local abundance of goats, but also with the density of vegetation habitats near houses including bromeliads, dry cacti, and fire- wood.97 The importance of the immediate environment in neotropical regions is even more striking because most species of Rhodnius are primarily associated with palm trees.98,99 Interestingly, in Panama an association was found between dog infections and the presence of palm trees in the peridomicile where the dog live and in the two nearest peridomiciles.100 Recently, a review of the relationships between palm trees and triatomines showed that the infestation of palm trees is not limited to rural areas but also occurs in urban areas; the palm trees that maintain the populations of triatomines, mostly species of the Rhodnius genus, favor the low continuous transmission of Chagas disease.101 Given that many triatomine species are attracted to light, or rather light guides their movements,102 house lights and street lighting undoubtedly play a role in the dispersal of triatomine bugs. A study in a village in Yucatan favors this hypothesis, showing a higher house infestation rate depending on their proximity to a public electric pole.103 Another study based on field collection and modeling explored the effect of different levels of illumination in a village: the model showed that increments in light could very significantly increase vector human contacts.104

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