The interplay of socio-structural factors and Chagas disease.

Chagas disease occurs in specific contexts marked by socio-cultural, political, economic, environmental and historical circumstances. Certain structural changes may influence the environment and people's living conditions, which, in turn, may trigger triatomin infestation (the Chagas disease insect vector) and provoke a higher risk of infection. Briceño-León [15] and Mastrangelo [16] described such case in the Amazon Region and Argentina, respectively: a shift in economic development during the 1980s towards industrial production and international trade played an important role determining social and environmental changes, which led to deterioration in living conditions. Land expropriations and deforestation forced families to migrate and engage in wage labor. Triatomins, previously located in more wooded areas, began occupying domestic spaces; and household re-infestation increased, in part because of its precarity.

Several reviewed studies focused on migration and stigmatization of infected people as pathways that caused their living conditions to deteriorate. Bayer et al. [17] showed how, in neighboring communities in Peru, vulnerability to triatomine infestation depended on the socio-economic processes underlying migration and settlement patterns. Displacements from endemic rural areas to urban settings or from non-endemic areas to endemic areas - for permanent or temporal labor - contributed to the appearance of infections in urban and non-endemic rural areas [16]–[20]. Other studies explored how the stigmatization of poor and rural populations and the discrimination of infected individuals affected their access to health-care and working conditions. Studies in different parts of Argentina [16], [21]–[22] described the mistreatment and discrimination that ethnic groups experienced in medical contexts, limiting their access to care. Employment-related stigma and discrimination [18], [23]–[24] was highlighted in urban settings [18], [23], [25]–[26], where Chagas disease - even positive serology regardless of symptoms – often resulted in labor exclusion. Chagas sufferers therefore commonly avoided the diagnostic tests that were often a prerequisite for employment, and sought informal sector, which caused deteriorations in living conditions. Chagas-related stigma also affected more socially and economically favored groups [18], [26]–[27]. Chagas disease's association with filth, neglect and misery led such groups to ignore possible infections, avoid testing, and meant that positive diagnosis caused great suffering.

Health practices.

Hygienic habits, household clutter, or cohabitation with domesticated animals were often identified as behaviors influencing Chagas prevention, and the persistence of the triatomine vector in dwellings [16], [18]–[19], [21]–[22], [25]–[26], [28]–[32]. Caballero Zamora et al. [28] and Rojas et al. [29] explained these behaviors in terms of a lack of knowledge about Chagas disease and its transmission. Therefore, as Sanmartino et al. [30] described, greater knowledge of Chagas disease would drive communities to acquire new health-related behaviors.

However, this was not always the case, and other authors, including Sanmartino in subsequent research, suggested that increased knowledge of Chagas disease was not always enough to change practices [16], [18]–[19], [25], [28]: “risk perceptions” [16], [18]–[19], [25], [28], and the ways of thinking about Chagas within a population's worldview [16], [18], [21]–[22], [25]–[26], [31]–[32] might explain behaviors. Five studies [16], [18]–[19], [25], [28] suggested that community members' views about the danger of triatomins and Chagas disease often differed from those of policy makers and clinicians. For example, in some highly endemic areas, where living conditions were demanding and the vector very common, Chagas disease was not perceived as a threat or, at least, as a health priority. Therefore, behavior was not always researchers expected. Moreover, an absence of symptoms and of an impact on everyday activities contributed to the naturalization and normalization of Chagas disease [25]–[26], [31], which influenced care seeking [19].

Insight into different ways of thinking about Chagas disease, its socio-cultural representations, was however seen as crucial to understand behavior and explain why knowledge about Chagas disease does not always imply behavior change [16], [18], [21]–[22], [25]–[26], [31]–[32]. For example, taking into account the failure of previous preventive programs based on increasing knowledge amongst indigenous populations in Las Lomitas, Argentina, Sosa-Estani [22] highlighted how, from the indigenous (pilagá) point of view, disease causation was explained in personalistic terms, or as violation of taboos or social norms. Preventive and curative practices may be therefore deeply linked to such representations, rather than the parasite or insect-vector. In Bolivia [28], some indigenous understanding of the vector as bearers of good luck was also a way to explain inaction against triatomines. In “peri-domestic” settings of Argentina's Gran Chaco region, the failures of vector control activities were attributed to differences between the conceptions of “landscape”, “wild” and “domesticated” used in preventive programs and those of the target population [16]. Preventive programs differentiated “domestic” from “peri-domestic” spaces as an indicator of human proximity to the insect vector, whereas the local population conceived these spaces as a continuum, allowing humans, animals and plant material brought from the mountain to cohabit “domestic” spaces.

Biomedical understandings of Chagas disease.

Particular ways of thinking about Chagas disease are not unique to target populations. Scientists' and health professionals' understandings are also developed in specific contexts and can affect their work. Kreimer et al. [3] reflected historically on the production of scientific knowledge on Chagas disease in Argentina: the “problem of Chagas” was defined according to the interests of different stakeholders, which involved recognizing certain facts and neglecting others. Historically, revised definitions of appropriate intervention strategies have also involved re-conceptualizations of Chagas disease: first seen as a problem of precarious living conditions; then as a question of fumigation; and finally, as a matter for basic research, for which molecular biology was prioritized. Ramos et al. [33] addressed the role of Brazilian mass media in the construction of the problem: positive assessments of Chagas' control strategies contributed to the social demobilization of a problem that was not yet under control.

Addressing health professionals' understandings of Chagas disease in an Argentinean urban context and in Brazil, Sanmartino [34] and Uchoa et al. [24] highlighted how a lack of relevant training and their own stereotypes affected the care they provided.

The patient's experience of Chagas disease.

Studies that addressed experiences of Chagas disease from the sufferer's perspective showed how social groups described a variety of conceptions about the disease [21], [24], [35]–[37]: local communities do not only have knowledge and specific ways of thinking about “Chagas”, but people also syncretize different kinds of knowledge, producing new hybridized understandings.

Evaluating the first Chagas' preventive programs in Brazil, Magnani et al. [35] concluded that the emphasis placed on disease contributed to a rapid and effective response: it provoked awareness of people's responsibility for health and their role in combating the vector, and led to new preventive practices. Nevertheless, prevention programs that neglected those already affected disregarded the meanings attributed to “Chagas”: new meanings, such as associations with death, fear, suffering, distrust, and despair, caused suffering and could affect health seeking behaviors. For example, two studies from Brazil [24], [35] described how some people developed informal yet adaptive strategies, such as denying Chagas disease, when the emotional burden was unbearable.

In contrast, studies in Brazil [35] and Argentina [18] described how a positive serology can be enough to consider oneself as ill, even if asymptomatic: although biomedical nosologies classify different degrees of severity of Chagas disease based on symptoms, infection by Trypanosoma was conflated with diagnosis of Chagas disease. A positive serology saw infected individuals identify themselves as sick, was sufficient to promote feelings of discomfort, and caused individual and social suffering. In all these situations, the patient-provider relationship was identified a key element in patients making sense of the disease [16], [18], [24], [35]–[36].

Institutional strategies.

There is no effective vaccine for Chagas disease and treatments are not 100% effective (in chronic cases effectiveness is unknown, although known to be low). Therefore, in endemic countries, the main strategies to combat the disease involve prevention interventions, control of blood banks and monitoring pregnant women. Preventive strategies have focused on controlling the most common vector through three principal interventions [25]: housing improvements, insecticide spraying, and health education. Many of the reviewed studies were designed to supplement, improve or evaluate Chagas prevention and/or control interventions [16], [18]–[20], [22], [25], [27], [28]–[32], [34]–[40]

Four studies [16], [18], [24], [35] highlighted the need for these approaches, but raised the question of whether achievements in vector control led to improvements in social and individual wellbeing. Surveillance and control activities were often dissociated from diagnosis, management and care. Moreover, because Chagas disease was problematized with reference to a narrow biological framing that neglected other political, economical, socio-cultural and individual dimensions, activities focused on infected individuals or those at risk of infection were neglected.

Access to health services.

In non-endemic countries, Chagas control is based on screening protocols for migrants considered at risk of infection. Several studies highlighted the importance of monitoring migrants' access and utilization of health services [41]–[45]. In Europe, migrants' lack of information about services and working constraints were the main barriers to accessing health services [41]–[45]. Immigration policies [41], migrants' mobility and Chagas disease's lack of symptoms [42] were also highlighted. Although one study [42] concluded that a “lack of knowledge” about Chagas disease prevented Latin American migrants from accessing screening services in Madrid, an ethnography conducted in Barcelona [43] revealed that migrants tend to feign ignorance during medical consultation - waiting for information from health personnel - and discuss their experiences and knowledge in other contexts. Although the author highlighted the importance of providing information about Chagas disease, associated fears and meanings explained why some migrants resisted screening. Indeed, meanings of Chagas disease and experiences within the health system in migrants' countries of origin were key to understanding health-seeking in Spain. In USA [45], a lack of awareness about Chagas disease among Latinos and fears of being diagnosed with a disease associated with death were also reported as barriers to testing and treatment, together with reservations about quality of care and costs.

Gender relationships and identity also influenced migrants' patterns of healthcare utilization: men were less likely to utilize healthcare services because they associated seeking help with weakness, which challenged their ideals of masculinity. Furthermore, due to their social role as breadwinners, men prioritized their families' economic situation over their own health- [43]–[44]. Indeed, men did not use to seek care until symptoms were unbearable [45]. In contrast, women had closer ties to the health system due to their reproductive role. Mothers' feelings of responsibility and guilt, if their children received a positive diagnosis, led them to use health services to ensure their children received treatment [43]–[45].

Studies emphasized the importance of developing community-oriented programs [41]–[43], as well as the need to consider the wider social determinants of health-care access services and health-related – such as the factors that limit patients' capacity to alter their dietary habits to reduce Chagas-related constipation [46] - into strategies and health recommendations [41], [46].

Migratory goals as incentives for seeking care.

A study conducted in Madrid [44] described how Bolivian migrants attended a specialized tropical disease unit with chronic symptomatic Chagas disease, and following the death or diagnosis of a friend or relative. Patients were referred by family, friends, or through primary health care facilities. However, migrants' main motivations for seeking care were not only associated with the somatic dimension of Chagas disease; patients' main concerns were linked to their life projects and dying before achieving their migratory goals: ensuring the welfare of relatives, who depended on their income and the health of their children, was essential [43]–[44]. Although social relations, the family and migratory projects were key to understanding health seeking, these motivations contrasted with a disease-centered approach utilized in control interventions and care programs. This contrast was complicated by the mostly asymptomatic nature of the disease, its association with death and severe illness, and the lack of cure or effective treatment.

Regarding treatment, some patients claimed that it could lengthen life, and hence was a guarantee of achieving migratory goals [43]–[44]. Other asymptomatic patients considered it an unnecessary risk, assuming that symptoms would only present after achieving their migratory goals [44]. Side effects and uncertain outcome were reasons for refusing or abandonment treatment.