A strategy for scaling up access to comprehensive care in adults with Chagas disease in endemic countries: The Bolivian Chagas Platform

Five-year serological and clinical evolution of chronic Chagas disease patients in Cochabamba, Bolivia

BACKGROUND

Chagas disease, caused by the parasite Trypanosoma cruzi, is a neglected infectious disease that exerts the highest public health burden in the Americas. There are two anti-parasitic drugs approved for its treatment-benznidazole and nifurtimox-but the absence of biomarkers to early assess treatment efficacy hinders patients´ follow-up.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a longitudinal, observational study among a cohort of 106 chronically T. cruzi-infected patients in Cochabamba (Bolivia) who completed the recommended treatment of benznidazole. Participants were followed-up for five years, in which we collected clinical and serological data, including yearly electrocardiograms and optical density readouts from two ELISAs (total and recombinant antigens). Descriptive and statistical analyses were performed to understand trends in data, as well as the relationship between clinical symptoms and serological evolution after treatment. Our results showed that both ELISAs documented average declines up to year three and slight inclines for the following two years. The recorded clinical parameters indicated that most patients did not have any significant changes to their cardiac or digestive symptoms after treatment, at least in the timeframe under investigation, while a small percentage demonstrated either a regression or progression in symptoms. Only one participant met the "cure criterion" of a negative serological readout for both ELISAs by the final year.

CONCLUSIONS/SIGNIFICANCE

The study confirms that follow-up of benznidazole-treated T. cruzi-infected patients should be longer than five years to determine, with current tools, if they are cured. In terms of serological evolution, the single use of a total antigen ELISA might be a more reliable measure and suffice to address infection status, at least in the region of Bolivia where the study was done. Additional work is needed to develop a test-of-cure for an early assessment of drugs´ efficacy with the aim of improving case management protocols.

Design and feasibility of an implementation strategy to address Chagas guidelines engagement focused on attending women of childbearing age and children at the primary healthcare level in Argentina: a pilot study

Background

Chagas is a public health problem, especially in Latin America, exacerbated by migratory movements and increasing urbanization. Argentina is among the countries with the highest estimated prevalence in the region, with 1,500,000 people infected, with mother to child as the main mode of transmission. Vertical transmission has been significantly reduced by treating women of childbearing age; several guidelines in the region recommend treatment as a primary prevention strategy for the child and a secondary prevention strategy for women and their families. Despite recommendations, women of childbearing age are not always treated, and children do not receive timely diagnosis and treatment. The objective of this research was to design an implementation strategy to improve using Chagas guidelines focused on attending women of childbearing age and children at the primary healthcare level and pilot it in three primary health care centers in Argentina.

Methods

We conducted a pilot feasibility study using the Consolidated Framework for Implementation Research. A qualitative process evaluation was conducted using semi-structured interviews with health care providers and observations in primary health care centers.

Results

We developed a multifaceted implementation strategy including training, flowcharts and reminders, a register of suspected and confirmed cases, and the selection of a management facilitator. The pilot study took place between September 2019 and May 2020. The implementation level was heterogeneous and varied depending on the components, being the facilitating factors, the simplicity of the intervention, professionals’ willingness to expand the indication of serologic tests, and staff commitment to the adoption of intervention components. The main barriers found were the change of authorities at the local level, some professionals´ reluctance to administer etiological treatment, staff shortages, lack of diagnostic supplies, and the health emergency caused by the COVID-19 pandemic.

Conclusions

Behavioral change strategies should be applied to improve implementation to address some of the main barriers, including support actions offered by opinion leaders, medical experts, and local health authorities. Rapid diagnostic tests should be readily available to maintain behavior changes. We suggest further refinement of the strategy and its implementation in more centers to assess outcomes prospectively with a hybrid implementation research design.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-022-01886-6.

Long-Standing International Cooperation in Parasitology Research: A Summary of 35 Years of Activities in the Bolivian Chaco

The Bolivian Chaco is a semiarid region with a low population density, situated in the southeast part of the Plurinational State of Bolivia. Here, despite the improvements of the last 15 years, poverty remains high in rural areas, where social vulnerability is widespread. The Guaraní ethnic group often lives in isolated communities with a low standard of hygiene and sanitation. This epidemiological scenario favors the spread of transmissible diseases, including several parasitic infections belonging to the neglected tropical diseases (NTDs) group. In this area, a long-standing research activity, built upon the synergism between local and foreign institutions, has been established since the late 1980s and helps to fill in the knowledge gap about the epidemiology dynamics of soil-transmitted helminths, vector-borne parasites, and other parasitic diseases. A 35-year history of cooperation programs in parasitology research has contributed to informing local health authorities of the NTD burden in the Bolivian Chaco and, ultimately, supports local healthcare providers in the management of parasitic diseases.

A Phase 2, Randomized, Multicenter, Placebo-Controlled, Proof-of-Concept Trial of Oral Fexinidazole in Adults With Chronic Indeterminate Chagas Disease

BACKGROUND

Chagas disease (CD) has significant global health impact, but safe, effective treatments remain elusive. The nitroimidazole fexinidazole is a potential treatment.

METHODS

This double-blind, randomized, placebo-controlled, dose-finding, proof-of-concept study was conducted in Bolivia. Adults with serologically confirmed chronic indeterminate CD and positive PCR were randomly assigned to 1 of 6 fexinidazole regimens (1200 or 1800 mg/day for 2, 4, or 8 weeks) or placebo. Target recruitment was 20 patients/arm. The primary endpoint was sustained parasitological clearance by serial negative qPCR from end of treatment (EOT) until 6 months follow-up in the intention-to-treat (ITT) population. Follow-up was extended to 12 months.

RESULTS

Enrollment was interrupted after 4/47 patients presented with transient asymptomatic grade 3 and 4 neutropenia. Treatment of ongoing patients was stopped in all patients administered >2 weeks. A total of 40 patients received treatment with fexinidazole from 3 days to 8 weeks. Delayed-onset neutropenia (n = 8) and increased liver enzymes (n = 8) were found in fexinidazole patients vs none in the placebo arm. In the ITT analysis, sustained parasitological clearance from EOT to 12 months follow-up varied between 66.7% (1200 mg-2 week) and 100.0% (1800 mg-2 week). Rapid, sustained clearance of parasitemia was observed in all treated patients with available data, but not in any patients in the placebo group, at 12 months (P = .0056). Further exploratory exposure-response analysis suggested low dosages of fexinidazole may be safe and effective.

CONCLUSIONS

Further evaluation is needed to establish fexinidazole's minimum effective dosage and risk-benefit relationship. Results suggest potential for effective treatment regimens <10 days.

CLINICAL TRIALS REGISTRATION

NCT02498782.

Population movements, borders, and Chagas disease

Currently, Chagas disease is a complex global health problem with local and global implications. In the present article, we approach this complexity from the perspective of human mobility and its effects on people's health in places of origin and in transit and destination. We raise key concepts such as human mobility - understood as a possible socio-structural and economic determination of health -, the associated social and institutional barriers and the processes of social exclusion related to Chagas disease. We also propose what we identify as emerging opportunities from the perspective of health as a right. Finally, we propose strategies aimed at addressing Chagas disease from a multidimensional and intersectional perspective in complex, diverse and interconnected territories through migration.

Translational research in Chagas disease: perspectives in nutritional therapy emerging from selenium supplementation studies as a complementary treatment

Translational research (TR) is an interdisciplinary branch of the biomedical field that seeks to connect its three supporting pillars: basic research on the bench, the hospital beds and other health system services, and the delivery of products for the well-being and health of the community. Here, we review the five transition stages of the TR spectrum, registering the lessons learned during > 20 years leading to the first clinical trial designed and performed in Brazil for testing a complementary treatment for Chagas disease (CD): the selenium trial (STCC). Lessons learned were: (1) to consider all the TR spectrum since the beginning of the project; (2) to start simultaneously animal studies and translation to humans; (3) to ensure a harmonious interaction between clinical and basic research teams; (4) to include MSc and PhD students only in pre-clinical and basic studies (TR0) or vertical clinical studies using retrospective samples and data (TR1); (5) to identify potential suppliers in the national commercial market for a future final treatment since the pre-clinical stage; (6) to keep an international network of experts as permanent advisers on the project. In the whole process, some perspectives were created: a complementary clinical trial for the opened questions and the construction of a Brazilian clinical CD platform.

Results and evaluation of the expansion of a model of comprehensive care for Chagas disease within the National Health System: The Bolivian Chagas network

Background

Most people with chronic Chagas disease do not receive specific care and therefore are undiagnosed and do not receive accurate treatment. This manuscript discusses and evaluates a collaborative strategy to improve access to healthcare for patients with Chagas in Bolivia, a country with the highest prevalence of Chagas in the world.

Methods

With the aim of reinforcing the Chagas National Programme, the Bolivian Chagas Platform was born in 2009. The first stage of the project was to implement a vertical pilot program in order to introduce and consolidate a consensual protocol-based healthcare, working in seven centers (Chagas Platform Centers). From 2015 on the model was extended to 52 primary healthcare centers, through decentralized, horizontal scaling-up. To evaluate the strategy, we have used the WHO ExpandNet program.

Results

The strategy has significantly increased the number of patients cared for, with 181,397 people at risk of having T. cruzi infection tested and 57,871 (31·9%) new diagnostics performed. In those with treatment criteria, 79·2% completed the treatment. The program has also trained a significant number of health personnel through the specific Chagas guidelines (67% of healthcare workers in the intervention area).

Conclusions

After being recognized by the Chagas National Programme as a healthcare model aligned with national laws and priorities, the Bolivian platform of Chagas as an innovation, includes attributes that they have made it possible to expand the strategy at the national level and could also be adapted in other countries.

The Bolivian Chagas Platform was born in 2009 to promote comprehensive care for Chagas disease (CD), a neglected tropical disease that affects more than a million people in Bolivia. A two-phase strategy was designed to introduce protocol-based healthcare in Bolivia through prevention, case-management, healthcare professionals training, and community activities. From an initial seven centers in the vertical phase (Chagas Platform centers), 52 healthcare primary healthcare centers adopted CD protocolized care in a second phase (Chagas Healthcare Network) through decentralized, horizontal scaling-up. 181,397 people at risk of having T. cruzi infection were tested (15%), 57,871 (31.9%) tested positive, and 18,582 (32.1%) were treated. Sixty-seven percent of healthcare workers were trained. Adequate domestic financial and human resources were ensured at the end of the scaling-up. Translational research and training activities improved evidence-based decision-making in clinical management. The Bolivian Chagas Platform as innovation, included attributes that enabled scaling-up at national and international level.

On-site experience of a project to increase access to diagnosis and treatment of Chagas disease in high-risk endemic areas of Colombia

Colombia has one of the largest burdens of Chagas disease globally, with about 438,000 people affected according to 2015 estimates. Despite this, < 1% of the population has had access to diagnosis and treatment. A patient-centered roadmap for Chagas disease was developed from 2015 onwards to address access barriers and increase diagnostic and therapeutic coverage and was implemented in five municipalities where Chagas disease is endemic. The mean number of people tested per year increased from 37 before the project to 262 following implementation, and the average days between medical order and diagnostic confirmation results decreased from 258 to 19. The mean days from diagnostic confirmation to treatment initiation decreased from 354 before the project to 135 after implementation. The 5,654 people tested included 3,467 women of childbearing age. The prevalence of T. cruzi infection was 11.5%, and thus far 266 people have received antitrypanosomal treatment. Collaborative creation and implementation of a patient-centered roadmap can address access barriers in specific contexts, helping to reduce the invisibility and burden of this neglected disease.

New chemotherapy regimens and biomarkers for Chagas disease: the rationale and design of the TESEO study, an open-label, randomised, prospective, phase-2 clinical trial in the Plurinational State of Bolivia

INTRODUCTION

Chagas disease (CD) affects ~7 million people worldwide. Benznidazole (BZN) and nifurtimox (NFX) are the only approved drugs for CD chemotherapy. Although both drugs are highly effective in acute and paediatric infections, their efficacy in adults with chronic CD (CCD) is lower and variable. Moreover, the high incidence of adverse events (AEs) with both drugs has hampered their widespread use. Trials in CCD adults showed that quantitative PCR (qPCR) assays remain negative for 12 months after standard-of-care (SoC) BZN treatment in ~80% patients. BZN pharmacokinetic data and the nonsynchronous nature of the proliferative mammal-dwelling parasite stage suggested that a lower BZN/NFX dosing frequency, combined with standard or extended treatment duration, might have the same or better efficacy than either drug SoC, with fewer AEs.

METHODS AND ANALYSIS

New ThErapies and Biomarkers for ChagaS infEctiOn (TESEO) is an open-label, randomised, prospective, phase-2 clinical trial, with six treatment arms (75 patients/arm, 450 patients). Primary objectives are to compare the safety and efficacy of two new proposed chemotherapy regimens of BZN and NFX in adults with CCD with the current SoC for BZN and NFX, evaluated by qPCR and biomarkers for 36 months posttreatment and correlated with CD conventional serology. Recruitment of patients was initiated on 18 December 2019 and on 20 May 2021, 450 patients (study goal) were randomised among the six treatment arms. The treatment phase was finalised on 18 August 2021. Secondary objectives include evaluation of population pharmacokinetics of both drugs in all treatment arms, the incidence of AEs, and parasite genotyping.

ETHICS AND DISSEMINATION

The TESEO study was approved by the National Institutes of Health (NIH), U.S. Food and Drug Administration (FDA), federal regulatory agency of the Plurinational State of Bolivia and the Ethics Committees of the participating institutions. The results will be disseminated via publications in peer-reviewed journals, conferences and reports to the NIH, FDA and participating institutions.

TRIAL REGISTRATION NUMBER

NCT03981523.

Community-based entomological surveillance in three Chagas disease-endemic regions in sub-Andean Bolivia

BACKGROUND

Chagas disease is endemic throughout most of Bolivia, with prevalence rates of 25% observed in some geographic areas located mainly in the sub-Andean region.

METHODS

Community-based entomological surveillance was carried out in the sub-Andean departments of Cochabamba (municipalities of Cochabamba, Punata and Sacaba), Tarija (municipality of Tarija) and Chuquisaca (municipality of Sucre). The surveillance parameters evaluated were: (i) the proportion of cards with the presence of triatomines; (ii) the distribution of positive cards by area; and (iii) the proportion of cards with the presence of infected triatomines.

RESULTS

Of the cards returned, in 852 (3.1%) there was a mention of the presence of triatomines. The species Triatoma infestans, Triatoma sordida and Triatoma guasayana were identified in 812 (95.3%), 39 (4.6%) and 1 (0.1%), respectively. The median monthly positivity rate of the cards during 2011-2018 was higher in Punata (9.1%; IQR=3.2-15.4%). The median monthly rate was highest in 2012 (2.7%; IQR=0-5.6%). Fifty positive cards (5.8%) presented insects that were positive for trypanosomatids, mainly in Cochabamba and Punata.

CONCLUSIONS

The report of triatomines foci by inhabitants represents an effective surveillance system coordinated by a network of specialized and multidisciplinary health centers. These strategies, which should be included in the health policies of endemic countries, enable extending and deepening the dialogue among technicians, communities and their local authorities.

Social determinants in the access to health care for Chagas disease: A qualitative research on family life in the "Valle Alto" of Cochabamba, Bolivia

Introduction

Chagas disease is caused by the Trypanosoma cruzi infection. It is a neglected tropical disease with considerable impact on the physical, psychological, familiar, and social spheres. The Valle Alto of Cochabamba is a hyperendemic region of Bolivia where efforts to control the transmission of the disease have progressed over the years. However, many challenges remain, above all, timely detection and health-care access.

Methods

Following the Science Shop process, this bottom-up research emerged with the participation of the civil society from Valle Alto and representatives of the Association of Corazones Unidos por el Chagas from Cochabamba. The aim of this study is to explore the social determinants in the living realities of those affected by Chagas disease or the silent infection and how families in the Valle Alto of Cochabamba cope with it. An interdisciplinary research team conducted a case study of the life stories of three families using information from in-depth interviews and performed a descriptive qualitative content analysis and triangulation processes.

Findings

Findings provide insights into social circumstances of the research subjects’ lives; particularly, on how exposure to Trypanosoma cruzi infection affects their daily lives in terms of seeking comprehensive health care. Research subjects revealed needs and shared their experiences, thus providing an understanding of the complexity of Chagas disease from the socioeconomic, sociocultural, political, and biomedical perspectives. Results enlighten on three dimensions: structural, psychosocial, and plural health system. The diverse perceptions and attitudes toward Chagas within families, including the denial of its existence, are remarkable as gender and ethnocultural aspects. Findings support recommendations to various stakeholders and translation materials.

Conclusions

Intersectional disease management and community involvement are essential for deciding the most appropriate and effective actions. Education, detection, health care, and social programs engaging family units ought to be the pillars of a promising approach.

"You Don't Have a Normal Life": Coping with Chagas Disease in Los Angeles, California

Chagas disease is the neglected tropical disease of greatest public health impact in the United States, where it affects over 300,000 people. Diverse barriers limit healthcare access for affected people; fewer than 1% have obtained testing or treatment. We interviewed 50 people with Chagas disease in Los Angeles, California, and administered a cultural consensus analysis questionnaire. Participants were asked about their experiences and perceptions of Chagas disease, access to healthcare, and strategies for coping with the disease. In participants' narratives, the physical and emotional impacts of the disease were closely interwoven. Participant explanatory models highlight difficulties in accessing care, despite a desire for biomedical treatment. Obtaining testing and treatment for Chagas disease poses substantial challenges for US patients.

Multi-criteria decision analysis approach for strategy scale-up with application to Chagas disease management in Bolivia

OBJECTIVE

Design and build a strategy construction and evaluation software system to help stakeholders to develop viable strategies to expand (and adapt) the Chagas Platform healthcare model through the primary healthcare system in Bolivia.

METHODS

The software was built based on a ranking of medical Interventions and Actions (needed to support Interventions' implementation) needed for comprehensive management of Chagas Disease in Bolivia. The ranking was performed using a Multi Criteria Decision Analysis (MCDA) methodology adapted to the WHO's building blocks framework. Data regarding the criteria and the rankings was obtained through surveys and interviews with health care professionals working on Chagas disease. The Analytical Hierarchy Process was used to construct the decision criteria weights. Data Envelopment Analysis was used to identify the Interventions that lay on the efficiency frontier of outcomes and the complexity of associated Actions. These techniques were combined with integer programing tools using the open-source software R to build a decision-making tool to assess the outcomes and complexity of any combination of Interventions and Actions. This model and tool were applied to data concerning the care of Chagas disease in Bolivia collected through surveys of experts. The tool works by loading the data from each specific context.

RESULTS

The initial set of Interventions and Actions recommended after analysis of the survey data was further refined through face-to-face interviews with field experts in Bolivia, resulting in a strategy of 18 Interventions and 15 Actions. Within the WHO model the Leadership and Governance building block came up as the one needing more support with Actions such as the inclusion of Chagas into Annual Municipal Operational Plans by appointing local and provincial coordinators.

CONCLUSION

This project established the suitability of the model for constructing healthcare strategies. The model could be developed further resulting in a decision-making tool for program managers in a wide range of healthcare related issues, including neglected and/ or prevalent diseases. The tool has the potential to be used at different stages of decision making by diverse stakeholders in order to coordinate activities needed to address a health problem.

How effective are rapid diagnostic tests for Chagas disease?

Introduction: Diagnosis of chronic Chagas disease relies on the agreement of two conventional serological tests based on distinct antigens. These require cold to preserve reagents and samples, and equipment and trained personnel to run them. Moreover, results turnaround may be delayed for several weeks risking a loss to follow-up of infected subjects, summoning major disadvantages to access diagnosis (and treatment) in many highly endemic areas.Areas covered: Recent studies have shown the versatility of rapid diagnostic tests for the detection of chronic Trypanosoma cruzi infections in referral centers and in field campaigns, with a performance equivalent to that of conventional tools. Remarkably, RDTs do not require cold storage and provide results within an hour. Additionally, they are easy-to-use and can work with a tiny volume of finger-pricked whole blood. Altogether, major advantages toward generalizing their use as an alternative to conventional tests.Expert opinion: Already in 2021, only a small percentage of T. cruzi-infected people are diagnosed and treated. The unsuitability of currently used diagnostics, and of the recommended algorithm, to the conditions found in many regions do not help to fill this gap. RDTs stand as a promising solution, even though geographical validation should precede their implementation.

Benznidazole for the treatment of Chagas disease

INTRODUCTION

Chagas disease affects 6-7 million people, mainly in the Americas, and benznidazole is one of the two therapeutic options available. Trypanocide treatment aims to eliminate the parasite from the body to prevent the establishment or progression of visceral damage, mainly cardiac and/or digestive. Remarkably, it helps interrupt vertical transmission when administered to women of childbearing age.

AREAS COVERED

We discuss the basic and scarce data regarding chemical, pharmacokinetic, and pharmacodynamic structure. We also collect the most important data from previous phase II and III studies, as well as studies currently underway and upcoming. We reflect on the main indications for treatment and its challenges, such as the profile of adverse effects in adults, the pharmaceutical formulations, the search for reliable biomarkers, as well as regulatory aspects and access barriers. Alternative strategies such as shorter regimens, lower doses, and fixed doses are currently being evaluated to improve access and the safety profile of this treatment.

EXPERT OPINION

Benznidazole is likely to continue to be the drug of choice for Chagas disease in the coming years. However, it would probably be with a different treatment scheme.

"We have already heard that the treatment doesn't do anything, so why should we take it?": A mixed method perspective on Chagas disease knowledge, attitudes, prevention, and treatment behaviour in the Bolivian Chaco

BACKGROUND

Chagas disease (CD) is highly endemic in the Bolivian Chaco. The municipality of Monteagudo has been targeted by national interventions as well as by Médecins Sans Frontières to reduce infection rates, and to decentralize early diagnosis and treatment. This study seeks to determine the knowledge and attitudes of a population with increased awareness and to identify remaining factors and barriers for sustained vector control, health care seeking behaviour, and access, in order to improve future interventions.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional survey was conducted among approximately 10% (n = 669) of the municipality of Monteagudo's households that were randomly selected. Additionally, a total of 14 in-depth interviews and 2 focus group discussions were conducted with patients and key informants. Several attitudes and practices were identified that could undermine effective control against (re-)infection. Knowledge of clinical symptoms and secondary prevention was limited, and revealed specific misconceptions. Although 76% of the participants had been tested for CD, only 18% of those who tested positive concluded treatment with benznidazole (BNZ). Sustained positive serologies after treatment led to perceived ineffectiveness of BNZ. Moreover, access barriers such as direct as well as indirect costs, BNZ stock-outs and a fear of adverse reactions triggered by other community members made patients opt for alternative treatments against CD such as veterinary ivermectin, used by 28% of infected participants in our study. The lack of accessible care for chronic complications as well as socioeconomic consequences, such as the exclusion from both job opportunities and bank loans contributed to the ongoing burden of CD.

CONCLUSIONS/SIGNIFICANCE

Large scale interventions should be accompanied by operational research in order to identify misconceptions and unintended consequences early on, to generate accessible data for future interventions, and for rigorous evaluation. An integrated, community-based approach tackling social determinants and including both traditional and animal health sectors might help to overcome current barriers and advocate for patients' rights.

Strengthening the Bolivian pharmacovigilance system: New surveillance strategies to improve care for Chagas disease and tuberculosis

Chagas disease (CD) and tuberculosis (TB) are important health problems in Bolivia. Current treatments for both infections require a long period of time, and adverse drug reactions (ADRs) are frequent. This study aims to strengthen the Bolivian pharmacovigilance system, focusing on CD and TB. A situation analysis of pharmacovigilance in the Department of Cochabamba was performed. The use of a new local case report form (CRF) was implemented, together with the CRF established by the Unidad de Medicamentos y Tecnología en Salud (UNIMED), in several healthcare centers. Training and follow-up on drug safety monitoring and ADR reporting was provided to all health professionals involved in CD and TB treatment. A comparative analysis of the reported ADRs using the CRF provided by UNIMED, the new CRF proposal, and medical records, was also performed. Our results showed that out of all patients starting treatment for CD, 37.9% suffered ADRs according to the medical records, and 25.3% of them were classified as moderate/severe (MS). Only 47.4% of MS ADRs were reported to UNIMED. Regarding TB treatment, 9.9% of all patients suffered ADRs, 44% of them were classified as MS, and 75% of MS ADRs were reported to UNIMED. These findings show that the reinforcement of the Bolivian pharmacovigilance system is an ambitious project that should involve a long-term perspective and the engagement of national health workers and other stakeholders at all levels. Continuity and perseverance are essential to achieve a solid ADR reporting system, improving patient safety, drug efficacy and adherence to treatment.

Animal models of Chagas disease and their translational value to drug development

INTRODUCTION

American trypanosomiasis, better known as Chagas disease, is a global public health issue. Current treatments targeting the causative parasite, Trypanosoma cruzi, are limited to two old nitroheterocyclic compounds; new, safer drugs are needed. New tools to identify compounds suitable for parasitological cure in humans have emerged through efforts in drug discovery.

AREAS COVERED

Animal disease models are an integral part of the drug discovery process. There are numerous experimental models of Chagas disease described and in use; rather than going through each of these and their specific features, the authors focus on developments in recent years, in particular the imaging technologies that have dramatically changed the Chagas R&D landscape, and provide a critical view on their value and limitations for moving compounds forward into further development.

EXPERT OPINION

The application of new technological advances to the field of drug development for Chagas disease has led to the implementation of new and robust/standardized in vivo models that contributed to a better understanding of host/parasite interactions. These new models should also build confidence in their translational value for moving compounds forward into clinical development.

Emerging agents for the treatment of Chagas disease: what is in the preclinical and clinical development pipeline?

INTRODUCTION

Chagas disease treatment relies on the lengthy administration of benznidazole and/or nifurtimox, which have frequent toxicity associated. The disease, caused by the parasite Trypanosoma cruzi, is mostly diagnosed at its chronic phase when life-threatening symptomatology manifest in approximately 30% of those infected. Considering that both available drugs have variable efficacy by then, and there are over 6 million people infected, there is a pressing need to find safer, more efficacious drugs.

AREAS COVERED

We provide an updated view of the path to achieve the aforementioned goal. From state-of-the-art in vitro and in vivo assays based on genetically engineered parasites that have allowed high throughput screenings of large chemical collections, to the unfulfilled requirement of having treatment-response biomarkers for the clinical evaluation of drugs. In between, we describe the most promising pre-clinical hits and the landscape of clinical trials with new drugs or new regimens of existing ones. Moreover, the use of monkey models to reduce the pre-clinical to clinical attrition rate is discussed.

EXPERT OPINION

In addition to the necessary research on new drugs and much awaited biomarkers of treatment efficacy, a key step will be to generalize access to diagnosis and treatment and maximize efforts to impede transmission.

Implications of asymptomatic infection for the natural history of selected parasitic tropical diseases

Progress has been made in the control or elimination of tropical diseases, with a significant reduction of incidence. However, there is a risk of re-emergence if the factors fueling transmission are not dealt with. Although it is essential to understand these underlying factors for each disease, asymptomatic carriers are a common element that may promote resurgence; their impact in terms of proportion in the population and role in transmission needs to be determined. In this paper, we review the current evidence on whether or not to treat asymptomatic carriers given the relevance of their role in the transmission of a specific disease, the efficacy and toxicity of existing drugs, the Public Health interest, and the benefit at an individual level, for example, in Chagas disease, to prevent irreversible organ damage. In the absence of other control tools such as vaccines, there is a need for safer drugs with good risk/benefit profiles in order to change the paradigm so that it addresses the complete infectious process beyond manifest disease to include treatment of non-symptomatic infected persons.

Healthcare Professionals and Students' Awareness of Chagas Disease: Design and Validation of Chagas Level of Knowledge Scale (ChaLKS)

There are few studies evaluating awareness of Chagas disease among healthcare professionals attending migrants from Latin America or working in Chagas-endemic areas. The objective of this study was to design and validate instruments for assessing knowledge about Chagas disease among healthcare students and residents as well as students and professionals of social and other health science disciplines. Two validated scales have been developed: the 10-item Chagas Level of Knowledge Scale for healthcare professionals (ChaLKS-Medical) and the 8-item ChaLKS-Social&Health for potential aid workers from those fields. Both scales were considered adequate in terms of readability, internal consistency, construct validity, and discriminant validity. The mean number of correct answers on the ChaLKS-Medical among respondents from non-healthcare versus healthcare sectors was 1.80 versus 7.00 (P < 0.001). The scores on the ChaLKS-Social&Health also discriminated between the knowledge levels in these two groups (1.76 versus 6.78, P < 0.001). Knowledge among medical/pharmacy students and residents on the ChaLKS-Medical was acceptable and different (mean: 5.8 and 7.4, respectively; P < 0.001). Respondents' knowledge of Chagas disease was greater in those who had previously received information on the disease; this was true in both respondents from the healthcare sector (mean correct answers, ChaLKS-Medical: 7.2 versus 4.3, P < 0.001) and in potential aid workers (mean correct answers, ChaLKS-Social&Health: 5.1 versus 1.1, P = 0.001). The metric properties of both scales are adequate for their use in supporting aid operations in Chagas-endemic countries or in providing health and social care to migrant populations in non-endemic countries.

WHF IASC Roadmap on Chagas Disease

Background

Chagas Disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi, with some of the most serious manifestations affecting the cardiovascular system. It is a chronic, stigmatizing condition, closely associated with poverty and affecting close to 6 million people globally. Although historically the disease was limited to endemic areas of Latin America recent years have seen an increasing global spread. In addition to the morbidity and mortality associated with the disease, the social and economic burdens on individuals and society are substantial. Often called the 'silent killer', Chagas disease is characterized by a long, asymptomatic phase in affected individuals. Approximately 30% then go on develop chronic Chagas cardiomyopathy and other serious cardiac complications such as stroke, rhythm disturbances and severe heart failure.

Methods

In a collaboration of the World Hearth Federation (WHF) and the Inter-American Society of Cardiology (IASC) a writing group consisting of 20 diverse experts on Chagas disease (CD) was convened. The group provided up to date expert knowledge based on their area of expertise. An extensive review of the literature describing obstacles to diagnosis and treatment of CD along with proposed solutions was conducted. A survey was sent to all WHF Members and, using snowball sampling to widen the consultation, to a variety of health care professionals working in the CD global health community. The results were analyzed, open comments were reviewed and consolidated, and the findings were incorporated into this document, thus ensuring a consensus representation.

Results

The WHF IASC Roadmap on Chagas Disease offers a comprehensive summary of current knowledge on prevention, diagnosis and management of the disease. In providing an analysis of 'roadblocks' in access to comprehensive care for Chagas disease patients, the document serves as a framework from which strategies for implementation such as national plans can be formulated. Several dimensions are considered in the analysis: healthcare system capabilities, governance, financing, community awareness and advocacy.

Conclusion

The WHF IASC Roadmap proposes strategies and evidence-based solutions for healthcare professionals, health authorities and governments to help overcome the barriers to comprehensive care for Chagas disease patients. This roadmap describes an ideal patient care pathway, and explores the roadblocks along the way, offering potential solutions based on available research and examples in practice. It represents a call to action to decision-makers and health care professionals to step up efforts to eradicate Chagas disease.

Interventions to bring comprehensive care to people with Chagas disease: Experiences in Bolivia, Argentina and Colombia

Chagas disease (CD) affects over six million people and is a leading cause of heart failure in the Americas. Few are able to access diagnosis and treatment for CD, resulting in a missed opportunity to prevent morbimortality. Integration of testing and treatment with the primary healthcare level is a key step in ensuring affected people receive timely antitrypansomal therapy, which increasing evidence shows can prevent chronic complications from the disease and halt congenital transmission. This article describes three collaborative projects focused on increasing access to testing and treatment for CD through primary healthcare facilities in Bolivia, Argentina, and Colombia.

Determinants of intentions to prevent triatomine infestation based on the health belief model: An application in rural southern Ecuador

INTRODUCTION

Control of triatomine infestation is a key strategy for the prevention of Chagas disease (CD). To promote this strategy, it is important to know which antecedents to behavioral change are the best to emphasize when promoting prevention.

OBJECTIVE

The aim of this study was to determine predictors for intention to prevent home infestation based on the Health Belief Model (HBM), a commonly used health intervention planning theory.

MATERIALS & METHODS

A cross-sectional study was conducted with 112 heads of household in six communities with endemic and high rates of triatomine infestation in Loja province, Ecuador. The data was collected by a questionnaire including perceived severity, susceptibility, benefits to action, barriers to action, and self-efficacy. These data were also used to predict actual infestation of homes.

RESULTS

Community members reported strong intentions to prevent home infestation. HBM constructs predicted about 14% of the observed variance in intentions. Perceived susceptibility and severity did not predict behavioral intention well; perceived barriers to small-scale action that reduce likelihood of infestation and self-efficacy in participating in surveillance systems did. Self-efficacy and perception of barriers were equally powerful predictors. The HBM constructs, however, did not predict well actual infestation.

CONCLUSION

The findings supported the HBM as a way to predict intentions to prevent infestation of the home by triatomine bugs. The findings highlight that messages emphasizing self-efficacy in participating in surveillance systems and overcoming barriers to small-scale action that reduce likelihood of infestation, rather than a focus on risk, should be central messages when designing and implementing educational interventions for CD. The gap between behavioral intention and actual infestation reveals the need to assess home practices and their actual efficacy to fully enact and apply the HBM.

A four-step process for building sustainable access to diagnosis and treatment of Chagas disease

The vast majority of people with Chagas disease (CD) are undiagnosed and untreated. Improving access to diagnosis and treatment for CD involves confronting a wide range of barriers. This report discusses a collaborative approach to eliminate barriers and increase the availability of CD testing and treatment. Potential areas for intervention are selected based on burden of disease, support of local champions, and commitment from national and local authorities. A 4D approach (diagnose, design, deliver, and demonstrate impact) is then implemented. The diagnose step involves gathering key stakeholders at a seminar to collaboratively identify important barriers and propose solutions. The design step creates a specific plan to act upon the seminar’s conclusions with consensus on core indicators. The deliver step entails implementing the plan at pilot locations, while simultaneously strengthening health system capacity for CD testing and treatment. Lastly, the demonstrate impact step compares baseline data with annual post-implementation data to measure progress. In Colombia, this approach has helped simplify testing procedures and increase CD testing and treatment access in pilot communities, though challenges remain. The 4D approach represents one of several pathways toward ensuring that the best therapeutic and diagnostic products reach people affected by neglected tropical diseases.

Proposed multidimensional framework for understanding Chagas disease healthcare barriers in the United States

BACKGROUND

Chagas disease (CD) affects over 300,000 people in the United States, but fewer than 1% have been diagnosed and less than 0.3% have received etiological treatment. This is a significant public health concern because untreated CD can produce fatal complications. What factors prevent people with CD from accessing diagnosis and treatment in a nation with one of the world's most advanced healthcare systems?

METHODOLOGY/PRINCIPAL FINDINGS

This analysis of barriers to diagnosis and treatment of CD in the US reflects the opinions of the authors more than a comprehensive discussion of all the available evidence. To enrich our description of barriers, we have conducted an exploratory literature review and cited the experience of the main US clinic providing treatment for CD. We list 34 barriers, which we group into four overlapping dimensions: systemic, comprising gaps in the public health system; structural, originating from political and economic inequalities; clinical, including toxicity of medications and diagnostic challenges; and psychosocial, encompassing fears and stigma.

CONCLUSIONS

We propose this multidimensional framework both to explain the persistently low numbers of people with CD who are tested and treated and as a potential basis for organizing a public health response, but we encourage others to improve on our approach or develop alternative frameworks. We further argue that expanding access to diagnosis and treatment of CD in the US means asserting the rights of vulnerable populations to obtain timely, quality healthcare.

Strategies to enhance access to diagnosis and treatment for Chagas disease patients in Latin America

INTRODUCTION

Chagas disease, caused by infection with the parasite Trypanosoma cruzi, represents a huge public health problem in the Americas, where millions of people are affected. Despite the availability of two drugs against the infection (benznidazole and nifurtimox), multiple factors impede their effective usage: (1) gaps in patient and healthcare provider awareness; (2) lack of access to diagnosis; (3) drug toxicity and absence of treatment algorithms to address adverse effects; (4) failures in drug supply and distribution; and (5) inconsistent drug efficacy against the symptomatic chronic stage. Areas covered: We review new approaches and technologies to enhance access to diagnosis and treatment to reduce the disease burden. We also provide an updated picture of recently published and ongoing anti-T. cruzi drug clinical trials. Although there has been progress improving the research and development (R&D) landscape, it is unclear whether any new treatments will emerge soon. Literature search methodologies included multiple queries to public databases and the use of own-built libraries. Expert opinion: Besides R&D, there is a major need to continue awareness and advocacy efforts by patient associations, local and national governments, and international agencies. Overall, health systems strengthening is essential to ensure vector control commitments, as well as patient access to diagnosis and treatment.

Antileishmanial and antitrypanosomal drug identification

Although the treatments for human African trypanosomiasis (HAT), leishmaniasis and Chagas disease (CD) still rely on drugs developed several decades ago, there has been significant progress in the identification, development and use of novel drugs and formulations. Notably, there are now two drugs in clinical trial for HAT, fexinidazole and acoziborole; the liposomal amphotericin B formulation AmBisome has become an essential tool for both treatment and control of visceral leishmaniasis; and antifungal triazoles, posoconazole and ravuconazole, together with fexinidazole, have reached clinical trials for CD. Several other novel and diverse candidates are moving through the pipeline; sustained funding for their clinical development will now be the key to bring new safe, oral, shorter-course treatments to the clinic.

Phenotypic screening approaches for Chagas disease drug discovery

INTRODUCTION

Chagas disease, caused by the parasite Trypanosoma cruzi, is a global public health issue. Current treatments targeting the parasite are limited to two old nitroheterocyclic drugs with serious side effects. The need for new and safer drugs has prompted numerous drug discovery efforts to identify compounds suitable for parasitological cure in the last decade. Areas covered: Target-based drug discovery has been limited by the small number of well-validated targets - the latest example being the failure of azoles, T. cruzi CYP51 inhibitors, in proof-of-concept clinical trials; instead phenotypic-based drug discovery has become the main pillar of Chagas R&D. Rather than focusing on the technical features of these screening assays, the authors describe the different assays developed and available in the field, and provide a critical view on their values and limitations in the screening cascade for Chagas drug development. Expert opinion: The application of technological advances to the field of Chagas disease has led to a variety of phenotypic assays that have not only changed the disease discovery landscape but have also helped us to gain a better understanding of parasite/host interactions. Recent examples of target resolution from phenotypic hits will uncover new opportunities for drug discovery for Chagas disease.