Different profiles and epidemiological scenarios: past, present and future

Abstract

The multiplicity of epidemiological scenarios shown by Chagas Disease, derived from multiple transmission routes of the aetiological agent, occurring on multiple geo-ecobiosocial settings determines the complexity of the disease and reveal the difficulties for its control. From the first description of the link between the parasite, the vector and its domestic habitat and the disease that Carlos Chagas made in 1909, the epidemiological scenarios of the American Trypanosomiasis has shown a dynamic increasing complexity. These scenarios changed with time and geography because of new understandings of the disease from multiple studies, because of policies change at the national and international levels and because human movements brought the parasite and vectors to new geographies. Paradigms that seemed solid at a time were broken down, and we learnt about the global dispersion of Trypanosoma cruzi infection, the multiplicity of transmission routes, that the infection can be cured, and that triatomines are not only a health threat in Latin America. We consider the multiple epidemiological scenarios through the different T. cruzi transmission routes, with or without the participation of a Triatominae vector. We then consider the scenario of regions with vectors without the parasite, to finish with the consideration of future prospects.

Urban vectors of Chagas disease in the American continent: A systematic review of epidemiological surveys

“…However, we are currently facing a new paradigm in the continent, in which biomedical, epidemiological, social and cultural aspects are combined in a multidimensional way [1]. In this scenario, the vectorial transmission of T. cruzi is maintained through populations of triatomines that colonize dwellings not only of rural or semi-rural environments, but also of purely urban environments [5,14]. The proportion of the Latin American population living in large urban agglomerations has increased significantly from 41% in 1950 to 82% at present [15].…”

“…Since the relationship found between the parasite, the vector, its domestic habitat and the disease by Carlos Chagas in 1909, the epidemiological, environmental, social, political and cultural scenarios of the disease have been modified, showing an increasing dynamic complexity [ 1 , 5 ]. In addition, during the last decades, these scenarios have also been modified by changes in policies at national and international levels, as well as by human migratory processes, which have enhanced the dispersion of the parasite and vectors through different geographical areas [ 5 ].…”

“…Triatomine-mediated transmission of T . cruzi has been recorded in several countries of South America and Central America, and incipiently recognized in areas of southern USA [ 5 ]. Currently, there are 157 described triatomine species (154 living species and three fossil species) [ 7 ], which differ both in their epidemiological relevance [ 8 ] and in aspects of their biology (habitats, food sources, life cycles, etc.).…”

“…In this scenario, the vectorial transmission of T . cruzi is maintained through populations of triatomines that colonize dwellings not only of rural or semi-rural environments, but also of purely urban environments [ 5 , 14 ]. The proportion of the Latin American population living in large urban agglomerations has increased significantly from 41% in 1950 to 82% at present [ 15 ].…”

Reflections on Chagas disease in the Amazon

“…The presence of the parasite could turn them into active transmission foci, a remote but not impossible eventuality that has already occurred in other latitudes. (1) In this scenario, it is pertinent to restore Pavlovsky's (1939) (2) theory of natural foci, which from an ecological and geographical point of view, helps to understand the impact of human activities on the transformation of natural foci of some zoonoses. The transformation of natural foci explains the changes in the circulation of parasites in household and peri-household environments and their adaptation to new epidemiological patterns.…”