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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., Competing Interests: The authors have declared that no competing interests exist.

Trial Registration: NCT02646943., Competing Interests: The authors have declared that no competing interests exist.

Objective: To quantify the costs of Chagas disease in Colombia from a societal perspective in 2017., Methods: A cost-of-illness analysis was carried out using a prevalence-based approach. Costs attributable to Chagas were estimated from a bottom-up strategy, using population attributable fractions. Indirect costs were calculated using the human capital approach., Results: The estimated total cost of diagnosed Chagas disease was US $13.1 million and included $5.7 million in direct medical costs, $1.5 million in direct nonmedical costs, and $5.8 million in indirect costs: absenteeism ($2.2 million), presenteeism ($3.1 million), and premature deaths ($515228). On average, people diagnosed with Chagas disease incurred $594 in medical expenses, and more than half of that expense was directly attributable to Chagas. The annual cost to society for a person with chronic Chagas disease was $4226., Conclusions: Chagas disease imposes a substantial financial burden on healthcare system and society. Economic cost of illness-related productivity losses is much more significant. Our research suggests that a health policy framework addressing as many of the social determinants of health as possible may be pivotal in containing social costs. Therefore, reducing this burden is not only the responsibility of the health system., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Therapeutic vaccines to prevent Chagas disease progression to cardiomyopathy are under development because the only available medications (benznidazole and nifurtimox) are limited by their efficacy, long treatment course, and side effects. Better understanding the potential clinical and economic value of such vaccines can help guide development and implementation., Methods: We developed a computational Chagas Markov model to evaluate the clinical and economic value of a therapeutic vaccine given in conjunction with benznidazole in indeterminate and chronic Chagas patients. Scenarios explored the vaccine's impact on reducing drug treatment dosage, duration, and adverse events, and risk of disease progression., Results: When administering standard-of-care benznidazole to 1000 indeterminate patients, 148 discontinued treatment and 219 progressed to chronic disease, resulting in 119 Chagas-related deaths and 2293 DALYs, costing $18.9 million in lifetime societal costs. Compared to benznidazole-only, therapeutic vaccination administered with benznidazole (25-75% reduction in standard dose and duration), resulted in 37-111 more patients (of 1000) completing treatment, preventing 11-219 patients from progressing, 6-120 deaths, and 108-2229 DALYs (5-100% progression risk reduction), saving ≤$16,171 per patient. When vaccinating determinate Kuschnir class 1 Chagas patients, 10-197 fewer patients further progressed compared to benznidazole-only, averting 11-228 deaths and 144-3037 DALYs (5-100% progression risk reduction), saving ≤$34,059 per person. When vaccinating Kuschnir class 2 patients, 13-279 fewer progressed (279 with benznidazole-only), averting 13-692 deaths and 283-10,785 DALYs (5-100% progression risk reduction), saving ≤$89,759. Therapeutic vaccination was dominant (saved costs and provided health benefits) with ≥ 5% progression risk reduction, except when only reducing drug treatment regimen and adverse events, but remained cost-effective when costing <$200., Conclusions: Our study helps outline the thresholds at which a therapeutic Chagas vaccine may be cost-effective (e.g., <5% reduction in preventing cardiac progression, 25% reduction in benznidazole treatment doses and duration) and cost-saving (e.g., ≥5% and 25%, respectively)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: The World Health Organization's 2020 Goals for Chagas disease include access to antiparasitic treatment and care of all infected/ill patients. Policy makers need to know the economic value of identifying and treating patients earlier. However, the economic value of earlier treatment to cure and prevent the Chagas' spread remains unknown., Methods: We expanded our existing Chagas disease transmission model to include identification and treatment of Chagas disease patients. We linked this to a clinical and economic model that translated chronic Chagas disease cases into health and economic outcomes. We evaluated the impact and economic outcomes (costs, cost-effectiveness, cost-benefit) of identifying and treating different percentages of patients in the acute and indeterminate disease states in a 2,000-person village in Yucatan, Mexico., Results: In the absence of early treatment, 50 acute and 22 new chronic cases occurred over 50 years. Identifying and treating patients in the acute stage averted 0.5-5.4 acute cases, 0.6-5.5 chronic cases, and 0.6-10.8 disability-adjusted life years (DALYs), saving $694-$7,419 and $6,976-$79,950 from the third-party payer and societal perspectives, respectively. Treating in the indeterminate stage averted 2.2-4.9 acute cases, 6.1-12.8 chronic cases, and 11.7-31.1 DALYs, saving $7,666-$21,938 from the third-party payer perspective and $90,530-$243,068 from the societal perspective. Treating patients in both stages averted ≤9 acute cases and ≤15 chronic cases. Identifying and treating patients early was always economically dominant compared to no treatment. Identifying and treating patients earlier resulted in a cumulative cost-benefit of $7,273-$224,981 at the current cost of identification and treatment., Conclusions: Even when identifying and treating as little as 5% of cases annually, treating Chagas cases in the acute and indeterminate stages reduces transmission and provides economic and health benefits. This supports the need for improved diagnostics and access to safe and effective treatment., Competing Interests: The authors have declared that no competing interests exist.

Insecticide spraying of housing units is an important control measure for vector-borne infections such as Chagas disease. As vectors may invade both from other infested houses and sylvatic areas and as the effectiveness of insecticide wears off over time, the dynamics of (re)infestations can be approximated by [Formula: see text]-type models with a reservoir, where housing units are treated as hosts, and insecticide spraying corresponds to removal of hosts. Here, we investigate three ODE-based models of this type. We describe a dual-rate effect where an initially very high spraying rate can push the system into a region of the state space with low endemic levels of infestation that can be maintained in the long run at relatively moderate cost, while in the absence of an aggressive initial intervention the same average cost would only allow a much less significant reduction in long-term infestation levels. We determine some sufficient and some necessary conditions under which this effect occurs and show that it is robust in models that incorporate some heterogeneity in the relevant properties of housing units.

After more than one century since its discovery, Chagas disease is still extremely prevalent in 21 Latin American countries. Chagas disease is one of the most concerning public health problems in Latin America; the overall cost of CD treatment is approximately 7 billion United States dollars per year and it has a strong social impact on populations. Little progress has been made regarding the access to diagnosis and treatment at the primary health care level, calling into question the current policies to ensure the right to health and access to essential medications. In this article, diverse dimensions of access to treatment for Chagas disease are reviewed, illustrating the present state of benznidazole medication in relation to global production capacity, costs, and needs. The findings are based on an investigation requested by Médecins Sans Frontières Brazil through a consultancy in 2015, aiming to estimate the current costs of benznidazole production.

Background: Chagas disease is currently prevalent in European countries hosting large communities from Latin America. Whether asymptomatic individuals at risk of Chagas disease living in Europe should be screened and treated accordingly is unclear. We performed an economic evaluation of systematic Chagas disease screening of the Latin American population attending primary care centres in Europe., Methods: We constructed a decision tree model that compared the test option (screening of asymptomatic individuals, treatment, and follow-up of positive cases) with the no-test option (screening, treating, and follow-up of symptomatic individuals). The decision tree included a Markov model with five states, related to the chronic stage of the disease: indeterminate, cardiomyopathy, gastrointestinal, response to treatment, and death. The model started with a target population of 100 000 individuals, of which 4·2% (95% CI 2·2-6·8) were estimated to be infected by Trypanosoma cruzi. The primary outcome was the incremental cost-effectiveness ratio (ICER) between test and no-test options. Deterministic and probabilistic analyses (Monte Carlo simulations) were performed., Findings: In the deterministic analysis, total costs referred to 100 000 individuals in the test and no-test option were €30 903 406 and €6 597 403 respectively, with a difference of €24 306 003. The respective number of quality-adjusted life-years (QALYs) gained in the test and no-test option were 61 820·82 and 57 354·42. The ICER was €5442. In the probabilistic analysis, total costs for the test and no-test option were €32 163 649 (95% CI 31 263 705-33 063 593) and €6 904 764 (6 703 258-7 106 270), respectively. The respective number of QALYs gained was 64 634·35 (95% CI 62 809·6-66 459·1) and 59 875·73 (58 191·18-61 560·28). The difference in QALYs gained between the test and no test options was 4758·62 (95% CI 4618·42-4898·82). The incremental cost-effectiveness ratio (ICER) was €6840·75 (95% CI 2545-2759) per QALY gained for a treatment efficacy of 20% and €4243 per QALY gained for treatment efficacy of 50%. Even with a reduction in Chagas disease prevalence to 0·05% and with large variations in all the parameters, the test option would still be more cost-effective than the no-test option (less than €30000 per QALY)., Interpretation: Screening for Chagas disease in asymptomatic Latin American adults living in Europe is a cost-effective strategy. Findings of our model provide an important element to support the implementation of T cruzi screening programmes at primary health centres in European countries hosting Latin American migrants., Funding: European Commission 7th Framework Program., (Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license. Published by Elsevier Ltd.. All rights reserved.)

Competing Interests: The authors have declared that no competing interests exist.

Although Spain is the European country with the highest Chagas disease burden, the country does not have a national control program of the disease. The purpose of this study is to evaluate the efficiency of several strategies for Chagas disease screening among Latin American residents living in Spain. The following screening strategies were evaluated: (1) non-screening; (2) screening of the Latin American pregnant women and their newborns; (3) screening also the relatives of the positive pregnant women; (4) screening also the relatives of the negative pregnant women. A cost-utility analysis was carried out to compare the four strategies from two perspectives, the societal and the Spanish National Health System (SNHS). A decision tree representing the clinical evolution of Chagas disease throughout patient's life was built. The strategies were compared through the incremental cost-utility ratio, using euros as cost measurement and quality-adjusted life years as utility measurement. A sensitivity analysis was performed to test the model parameters and their influence on the results. We found the "Non-screening" as the most expensive and less effective of the evaluated strategies, from both the societal and the SNHS perspectives. Among the screening evaluated strategies the most efficient was, from both perspectives, to extent the antenatal screening of the Latin American pregnant women and their newborns up to the relatives of the positive women. Several parameters influenced significantly on the sensitivity analyses, particularly the chronic treatment efficacy or the prevalence of Chagas disease. In conclusion, for the general Latin American immigrants living in Spain the most efficient would be to screen the Latin American mothers, their newborns and the close relatives of the mothers with a positive serology. However for higher prevalence immigrant population the most efficient intervention would be to extend the program to the close relatives of the negative mothers., (Copyright © 2015 Elsevier B.V. All rights reserved.)

As an evaluation scheme, we propose certifying for "control", as alternative to "interruption", of Chagas disease transmission by native vectors, to project a more achievable and measurable goal and sharing good practices through an "open online platform" rather than "formal certification" to make the key knowledge more accumulable and accessible.

Background: Given current neglect for Chagas disease in public health programs in Mexico, future healthcare and economic development policies will need a more robust model to analyze costs and impacts of timely clinical attention of infected populations., Methodology/principal Findings: A Markov decision model was constructed to simulate the natural history of a Chagas disease cohort in Mexico and to project the associated short and long-term clinical outcomes and corresponding costs. The lifetime cost for a timely diagnosed and treated Chagas disease patient is US$ 10,160, while the cost for an undiagnosed individual is US$ 11,877. The cost of a diagnosed and treated case increases 24-fold from early acute to indeterminate stage. The major cost component for lifetime cost was working days lost, between 44% and 75%, depending on the program scenario for timely diagnosis and treatment., Conclusions/significance: In the long term, it is cheaper to diagnose and treat chagasic patients early, instead of doing nothing. This finding by itself argues for the need to shift current policy, in order to prioritize and attend this neglected disease for the benefit of social and economic development, which implies including treatment drugs in the national formularies. Present results are even more relevant, if one considers that timely diagnosis and treatment can arrest clinical progression and enhance a chronic patient's quality of life.

Background: As Chagas disease continues to expand beyond tropical and subtropical zones, a growing need exists to better understand its resulting economic burden to help guide stakeholders such as policy makers, funders, and product developers. We developed a Markov simulation model to estimate the global and regional health and economic burden of Chagas disease from the societal perspective., Methods: Our Markov model structure had a 1 year cycle length and consisted of five states: acute disease, indeterminate disease, cardiomyopathy with or without congestive heart failure, megaviscera, and death. Major model parameter inputs, including the annual probabilities of transitioning from one state to another, and present case estimates for Chagas disease came from various sources, including WHO and other epidemiological and disease-surveillance-based reports. We calculated annual and lifetime health-care costs and disability-adjusted life-years (DALYs) for individuals, countries, and regions. We used a discount rate of 3% to adjust all costs and DALYs to present-day values., Findings: On average, an infected individual incurs US$474 in health-care costs and 0·51 DALYs annually. Over his or her lifetime, an infected individual accrues an average net present value of $3456 and 3·57 DALYs. Globally, the annual burden is $627·46 million in health-care costs and 806,170 DALYs. The global net present value of currently infected individuals is $24·73 billion in health-care costs and 29,385,250 DALYs. Conversion of this burden into costs results in annual per-person costs of $4660 and lifetime per-person costs of $27,684. Global costs are $7·19 billion per year and $188·80 billion per lifetime. More than 10% of these costs emanate from the USA and Canada, where Chagas disease has not been traditionally endemic. A substantial proportion of the burden emerges from lost productivity from cardiovascular disease-induced early mortality., Interpretation: The economic burden of Chagas disease is similar to or exceeds those of other prominent diseases globally (eg, rotavirus $2·0 billion, cervical cancer $4·7 billion) even in the USA (Lyme disease $2·5 billion), where Chagas disease has not been traditionally endemic, suggesting an economic argument for more attention and efforts towards control of Chagas disease., Funding: Bill & Melinda Gates Foundation, the National Institute of General Medical Sciences Models of Infectious Disease Agent Study., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Chagas disease, caused by the parasite Trypanosoma cruzi (T. cruzi), is the leading etiology of non-ischemic heart disease worldwide, with Latin America bearing the majority of the burden. This substantial burden and the limitations of current interventions have motivated efforts to develop a vaccine against T. cruzi., Methodology/principal Findings: We constructed a decision analytic Markov computer simulation model to assess the potential economic value of a T. cruzi vaccine in Latin America from the societal perspective. Each simulation run calculated the incremental cost-effectiveness ratio (ICER), or the cost per disability-adjusted life year (DALY) avoided, of vaccination. Sensitivity analyses evaluated the impact of varying key model parameters such as vaccine cost (range: $0.50-$200), vaccine efficacy (range: 25%-75%), the cost of acute-phase drug treatment (range: $10-$150 to account for variations in acute-phase treatment regimens), and risk of infection (range: 1%-20%). Additional analyses determined the incremental cost of vaccinating an individual and the cost per averted congestive heart failure case. Vaccination was considered highly cost-effective when the ICER was ≤1 times the GDP/capita, still cost-effective when the ICER was between 1 and 3 times the GDP/capita, and not cost-effective when the ICER was >3 times the GDP/capita. Our results showed vaccination to be very cost-effective and often economically dominant (i.e., saving costs as well providing health benefits) for a wide range of scenarios, e.g., even when risk of infection was as low as 1% and vaccine efficacy was as low as 25%. Vaccinating an individual could likely provide net cost savings that rise substantially as risk of infection or vaccine efficacy increase., Conclusions/significance: Results indicate that a T. cruzi vaccine could provide substantial economic benefit, depending on the cost of the vaccine, and support continued efforts to develop a human vaccine.

Background: Control and prevention of Chagas disease rely mostly on residual spraying of insecticides. In Argentina, vector control shifted from a vertical to a fully horizontal strategy based on community participation between 1992 and 2004. The effects of such strategy on Triatoma infestans, the main domestic vector, and on disease transmission have not been assessed., Methods and Findings: Based on retrospective (1993-2004) records from the Argentinean Ministry of Health for the Moreno Department, Northwestern Argentina, we performed a cost-effectiveness (CE) analysis and compared the observed CE of the fully horizontal vector control strategy with the expected CE for a vertical or a mixed (i.e., vertical attack phase followed by horizontal surveillance) strategy. Total direct costs (in 2004 US$) of the horizontal and mixed strategies were, respectively, 3.3 and 1.7 times lower than the costs of the vertical strategy, due to reductions in personnel costs. The estimated CE ratios for the vertical, mixed and horizontal strategies were US$132, US$82 and US$45 per averted human case, respectively. When per diems were excluded from the costs (i.e., simulating the decentralization of control activities), the CE of vertical, mixed and horizontal strategies was reduced to US$60, US$42 and US$32 per averted case, respectively., Conclusions and Significance: The mixed strategy would have averted between 1.6 and 4.0 times more human cases than the fully horizontal strategy, and would have been the most cost-effective option to interrupt parasite transmission in the Department. In rural and dispersed areas where waning vertical vector programs cannot accomplish full insecticide coverage, alternative strategies need to be developed. If properly implemented, community participation represents not only the most appealing but also the most cost-effective alternative to accomplish such objectives.

The neglected tropical diseases (NTDs) represent some of the most common infections of the poorest people living in the Latin American and Caribbean region (LAC). Because they primarily afflict the disenfranchised poor as well as selected indigenous populations and people of African descent, the NTDs in LAC are largely forgotten diseases even though their collective disease burden may exceed better known conditions such as of HIV/AIDS, tuberculosis, or malaria. Based on their prevalence and healthy life years lost from disability, hookworm infection, other soil-transmitted helminth infections, and Chagas disease are the most important NTDs in LAC, followed by dengue, schistosomiasis, leishmaniasis, trachoma, leprosy, and lymphatic filariasis. On the other hand, for some important NTDs, such as leptospirosis and cysticercosis, complete disease burden estimates are not available. The NTDs in LAC geographically concentrate in 11 different sub-regions, each with a distinctive human and environmental ecology. In the coming years, schistosomiasis could be eliminated in the Caribbean and transmission of lymphatic filariasis and onchocerciasis could be eliminated in Latin America. However, the highest disease burden NTDs, such as Chagas disease, soil-transmitted helminth infections, and hookworm and schistosomiasis co-infections, may first require scale-up of existing resources or the development of new control tools in order to achieve control or elimination. Ultimately, the roadmap for the control and elimination of the more widespread NTDs will require an inter-sectoral approach that bridges public health, social services, and environmental interventions.

The first U.S. ELISA test for T. cruzi antibodies was licensed by the Food and Drug Administration (FDA) on December 13, 2006. Blood banks have begun screening in absence of FDA recommendations for best implementation methods. We surveyed 2,029 blood donors at five California sites with three risk-based Chagas risk-screening questions. Semi-Markov models compared the cost-effectiveness of three testing strategies. 30% of donors screened positively. Screening all dominated doing nothing, being less costly, and saving more lives. The choice to "screen and test" compared with "testing all" varied by Chagas prevalence, "screening and testing" being cost-effective for high (0.004) and low (0.00004) prevalences, and "testing all" cost-effective for moderate risk (0.0004). It is cost-effective to screen by ELISA rather than do nothing. The best strategy depends on site-specific risk. Census estimates of Hispanics do not predict donor risk well. We suggest using our screening questions to determine risk level and most cost-effective testing strategy.

Background: The objective of this study is to report the costs of Chagas disease in Colombia, in terms of vector disease control programmes and the costs of providing care to chronic Chagas disease patients with cardiomyopathy., Methods: Data were collected from Colombia in 2004. A retrospective review of costs for vector control programmes carried out in rural areas included 3,084 houses surveyed for infestation with triatomine bugs and 3,305 houses sprayed with insecticide. A total of 63 patient records from 3 different hospitals were selected for a retrospective review of resource use. Consensus methodology with local experts was used to estimate care seeking behaviour and to complement observed data on utilisation., Findings: The mean cost per house per entomological survey was $4.4 (in US$ of 2004), whereas the mean cost of spraying a house with insecticide was $27. The main cost driver of spraying was the price of the insecticide, which varied greatly. Treatment of a chronic Chagas disease patient costs between $46.4 and $7,981 per year in Colombia, depending on severity and the level of care used. Combining cost and utilisation estimates the expected cost of treatment per patient-year is $1,028, whereas lifetime costs averaged $11,619 per patient. Chronic Chagas disease patients have limited access to healthcare, with an estimated 22% of patients never seeking care., Conclusion: Chagas disease is a preventable condition that affects mostly poor populations living in rural areas. The mean costs of surveying houses for infestation and spraying infested houses were low in comparison to other studies and in line with treatment costs. Care seeking behaviour and the type of insurance affiliation seem to play a role in the facilities and type of care that patients use, thus raising concerns about equitable access to care. Preventing Chagas disease in Colombia would be cost-effective and could contribute to prevent inequalities in health and healthcare.

The Southern Cone Initiative (Iniciativa de Salud del Cono Sur, INCOSUR) to control domestic transmission of Trypanosoma cruzi is a substantial achievement based on the enthusiasm of the scientific community, effective strategies, leadership, and cost-effectiveness. INCOSUR triggered the launch of other regional initiatives in Central America and in the Andean and Amazon regions, which have all made progress. The Central American Initiative targeted the elimination of an imported triatomine bug (Rhodnius prolixus) and the control of a widespread native species (Triatoma dimidiata), and faced constraints such as a small scientific community, the difficulty in controlling a native species, and a vector control programme that had fragmented under a decentralized health system. International organizations such as the Japan International Cooperation Agency (JICA) have played an important role in bridging the gaps between fragmented organizational resources. Guatemala achieved virtual elimination of R. prolixus and ;reduction of Tri. Dimidiata and El Salvador and Honduras revitalized their national programmes. The programme also revealed new challenges. Tri. dimidiata control needs to cover a large geographic area efficiently with stratification, quality control, community mobilization, and information management. Stakeholders such as the National Chagas Program, the local health system and their communities, as well as local government must share responsibilities to continue comprehensive vector control.

Chagas disease, named after Carlos Chagas who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, transmitted to humans by blood-sucking triatomine bugs and by blood transfusion. Chagas disease has two successive phases, acute and chronic. The acute phase lasts 6 to 8 weeks. After several years of starting the chronic phase, 20% to 35% of the infected individuals, depending on the geographical area will develop irreversible lesions of the autonomous nervous system in the heart, esophagus, colon and the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980's as a result of the demographically representative cross-sectional studies carried out in countries where accurate information was not available. A group of experts met in Bras lia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country program in the Southern Cone countries the transmission of Chagas disease by vectors and by blood transfusion has been interrupted in Uruguay in1997, in Chile in 1999, and in 8 of the 12 endemic states of Brazil in 2000 and so the incidence of new infections by T. cruzi in the whole continent has decreased by 70%. Similar control multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been recorded to ensure the interruption of the transmission of Chagas disease by 2005 as requested by a Resolution of the World Health Assembly approved in 1998. The cost-benefit analysis of the investments of the vector control program in Brazil indicate that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the program is a health investment with good return. Since the inception in 1979 of the Steering Committee on Chagas Disease of the Special Program for Research and Training in Tropical Diseases of the World Health Organization (TDR), the objective was set to promote and finance research aimed at the development of new methods and tools to control this disease. The well known research institutions in Latin America were the key elements of a world wide network of laboratories that received - on a competitive basis - financial support for projects in line with the priorities established. It is presented the time line of the different milestones that were answering successively and logically the outstanding scientific questions identified by the Scientific Working Group in 1978 and that influenced the development and industrial production of practical solutions for diagnosis of the infection and disease control.

Chagas disease (also known as American trypanosomiasis) is now ranked as the most serious parasitic disease of the Americas, with an economic impact far outranking the combined effects of other parasitic diseases such as malaria, schistosomiasis and leishmaniasis. Although the chronic infection remains virtually incurable, transmission can be halted by eliminating the domestic insect vectors and screening blood donors to avoid transfusional transmission. In line with this strategy, governments of the six Southern Cone countries (Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay) launched in 1991 an ambitious initiative to control Chagas disease through elimination of the main vector, Triatoma infestans, and large-scale screening of blood donors. Now at its mid-point, the programme has achieved remarkable success, with transmission halted over vast areas of the previously endemic regions. Well over 2 million rural houses have been sprayed to eliminate T. infestans, and the programme has already shown significant economic rates of return in addition to the medical and social benefits.

Chagas disease has been controlled in the Department of Anta, Province of Salta, Argentina, through a series of vector control interventions beginning in 1983. Based on data from this programme, together with estimates of the value of benefits accruing to the programme due to avoidance of new cases of Chagas disease, we present an analysis of costs and benefits of the vector control interventions. Under all assumptions, the interventions have been highly profitable from a societal point of view, with an internal rate of return in excess of 60%. The net present value of benefits accruing to the programme is estimated to be above US$7 million.

According to the gathered information from the 1992 Chile census and an extensive epidemiological field study of Chagas' disease in rural-periurban sections of the seven most northern regions where this malady is endemic, the following epidemiological outline arises: Total population in the country 13,348,401. Population in endemic regions 8,824,205 (urban 8,050,700, rural 773,505). Number of infected 142,000 (16.7%). Total number of cardiopathies 26,554 (18.7%). In considering the regime of fees for health attentions of the National Health Funds--including hospitalization, laboratory tests and surgical interventions--in its minimal prices plus the value of medicaments, it is possible to produce some estimates on the cost of attention and treatment, in U.S. dollars, of the chagasic patient. Average annual cost of a patient with chronic chagasic cardiopathy U.S. $439.29 to U.S. $584.25 If these values are multiplied by 26,554 give rise to a figure ranging from U.S. $11,644,906 to U.S. $15,514,474.

From a global perspective, Chagas disease represents the third largest tropical disease burden after malaria and schistosomiasis. The estimated average annual per-capita gross domestic product in Latin America is US$2,966. The economic loss for the continent due to early mortality and disability by this disease in economically most productive young adults currently amounts to US$8,156 million which is equivalent to 2.5% of the external debt of the whole continent in 1995. In 1991, the Ministers of Health of Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay, launched the Southern Cone Initiative for elimination of transmission of Chagas disease. The progress towards elimination of vectorial and transfusional transmission of Chagas disease in Uruguay, Chile, Argentina and Brazil has been documented by reports from the national control programmes of the above countries. Current data on disinfestation of houses, coverage of screening in blood banks and serology in children and young adults indicate that the interruption of the vectorial and transfusional transmission of Chagas disease will be achieved in these countries as follows: Uruguay and Chile in 1999, Brazil and Argentina in 2003. By eliminating the transmission of Chagas disease in the above countries, the incidence of the disease in the whole of Latin America will be reduced by more than 70%.