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Health/Disease 18/10/2022

The dynamic health-disease process

Danielle Grynszpan

Laboratory of Biology of Interactions, Instituto Oswaldo Cruz/Fiocruz


Attention must be drawn to the fact that there is no such thing as total health or an absolute state of disease; what there is a health/disease process that clearly moves towards the disease – in the case of Chagas – the worse the socio-environmental conditions. In general, diseases, especially infectious-parasitic ones, are the product of greater environmental imbalance and lesser social equity!

As indicated in the Guide to Epidemiological Surveillance, recently published by the Ministry of Health (2014), a set of low-cost actions can be carried out to promote health.

However, only through education will populations be able to perceive the origins of the problems and appropriate knowledge about the necessary intervention strategies – in this way, with social participation, solutions will be collectively constructed and the process, dynamic, will revert towards the health of gradual but lasting way.

Attention! An educational process is long, not immediate, and cannot be summarized in information that is transmitted unidirectionally. Education in science, health and the environment demands cultural exchanges in which all social actors participate: scientists, health professionals, teachers, rural and school workers, among others – all equally important in the fight for better living and health conditions!

Deforestation and broken cycles: wounds that open

Although the subject is still controversial, the risk of Chagas’ disease remaining endemic is increasing, according to some scientists, for the following reasons: a) migration of infected human populations from their regions of origin, accompanied by domestic animals (such as dogs and cats) or other reservoirs and vectors (also infected with Trypanosoma cruzi) that are already adapted to household conditions; b) uncontrolled deforestation and colonization, altering the balance between reservoirs and wild vectors; c) favorable adaptation of reservoirs and wild vectors, with Trypanosoma cruzi, to peridomiciliary environments as a food alternative (in addition to humans, domestic animals or animals that cohabit with them, such as opossums and rodents can be infected). Cases of the acute form of Chagas’ disease were recently reported in Paraná, which must have occurred by oral transmission after ingestion of sugarcane juice contaminated with wild barber bug feces.

Endemic expansion risk: education and citizenship

The risk that Chagas’ disease may also become endemic in the Brazilian Amazon is primarily linked to the transposition from the wild to the domestic cycle. The endemic in the Amazon can also result from the domestic cycle already established in endemic areas in other regions of the country, such as the Southeast. It is known that among the main factors linked to the risk of spreading endemic diseases is the low human development index: investment in education has been insufficient, which has contributed to environmental devastation.

Fires and all types of deforestation have accompanied human migrations in search of better living and working conditions, a problem that has been expressed by the lack of construction of healthy housing. Precarious houses, such as “wattle and daub” or mud-brick houses, facilitate, or even promote, the domiciliation of vector insects (barber bugs). The lack of environmental sanitation is associated with the lack of social mobilization – better living conditions are the result of conquest. Environmental education work, integrated with health education, must be developed so that populations can claim the right to health guaranteed by the “Citizen Constitution” of Brazil of 1988:


States (Amazon, Ceará, Rio de Janeiro, and São Paulo)

  1. Chagas’ Disease in the Amazon

The Brazilian Amazon is a region known for its natural wealth, and especially for its biodiversity – and this is important for the maintenance of life. According to Coura, Junqueira and Giordano (1994), at least eighteen species of triatomines associated with numerous wild reservoirs can be found there. This means that most triatomines are not infected with Trypanosoma cruzi(or similar) – and there is still a relatively low number of human cases described with Chagas’ disease. Although triatomines, also known as “barber bugs”, are associated with vector transmission of Chagas’ disease, care must be taken in interpreting situations in everyday reality because there are other factors, especially socio-economic ones, that are determinant for the introduction and maintenance of this type of endemic.

  1. Chagas’ Disease in the State of Ceará

The State of Ceará occupies an area of 146,817 km², but its population is unevenly distributed, rare in the wilderness and dense in the mountains. The houses of the inhabitants of the municipality are typical of poor regions, with the floor and walls made of beaten clay or mud in areas of lower socioeconomic level. Epidemiological studies on Chagas’ disease in the region are unanimous in stating that it is the type of housing that has been causing the greatest infection, serving wild triatomines as artificial ecotopes. The settlement of families in areas of deforestation seems to be an important factor that conditions the higher prevalence of the disease.

  1. The case of Poço das Antas, State of Rio de Janeiro

The Poço das Antas Biological Reserve is located in the municipality of Silva Jardim, in the State of Rio de Janeiro. In this region, one of the most recognized programs for the conservation of an endangered species is being developed: the golden lion tamarin (Leontopithecus rosalia). The conservation program includes reintroduction and translocation, where isolated groups of golden lion tamarins, found in small remnants of Atlantic Forest, are transferred to another reserve. However, this program may be exposing golden lion tamarins to infection by a subpopulation of Trypanosoma cruzi, which seems to be also correlated with human infection at the site.

Therefore, it is essential to introduce environmental education programs in conservation units to guide professionals in service as well as visitors, in order to avoid a greater dispersion of vectors in nature and to establish integrated health and environment programs in areas of conservation.

  1. Chagas’ Disease in the State of São Paulo

Diseases evolve along with the societies in which they are inserted, resulting from the way in which the natural space is occupied and exploited.

According to Silva (1999), it was with the introduction of large-scale coffee plantations in São Paulo, initially in the Vale do Paraíba, that an endemic area for Chagas’ disease was constituted. This situation seems to be related to deforestation and disorderly occupation in precarious housing.

The presence of Triatoma infestans, colonizing these types of dwellings, has been used as an indicator of the occurrence of Chagas’ disease transmission. due to the quantity and extent of its distribution, the triatomine has been considered the most important vector in São Paulo. It can be said that its dispersion is confused with the distribution of the endemic itself.

But it is worth remembering that triatomines cannot be blamed for the illness of populations! They are also part of our country’s biodiversity. In fact, it would be more appropriate to attribute the endemics to the triangle “deforestation – unhealthy housing – lack of investment in education.” These are the conditions that have contributed to the expansion of Chagas’ disease in São Paulo, a phenomenon that has been repeated nationwide.