Chagas prevention and control in an endemic area from the Argentinian Gran Chaco Region: Data from 14 years of uninterrupted intervention.

BACKGROUND: Chagas Disease (ChD) is a Neglected Tropical Disease (NTD) affecting 6 to 7 million people worldwide, mostly from Latin America. In Argentina, a national control program has been implemented since 1962, yet there are still an estimated 1.6 million infected individuals. Control programs were based almost exclusively on entomological surveillance and chemical control of households and were not continuous given a lack of coordination and resources. Argentina´s ChD program was originally vertical and centralized; later, it was partially and, in general, unsuccessfully transferred to the provinces. Herein, we describe the implementation of a control program for ChD with an ecohealth approach in rural settlements around the city of Añatuya, Santiago del Estero. METHODS: The program included yearly household visits for entomological surveillance and control, health promotion workshops, and structural house improvements. Improved structures included internal and external walls and roofs, as well as the construction of water wells and latrines, and the organization and improvement of peri-domestic structures. Activities were carried out by specifically trained personnel except for house improvements, which were performed by the community, under technical guidance and provision of materials. Data was collected using standardized questionnaires for household characterization, entomological infestation status and chemical control activities. RESULTS: This program was continuously implemented since 2005 with high community participation and adherence, incorporating 13 settlements and 502 households. During the surveillance phase, 4,193 domiciliary inspections were performed, and both the intra- and peri-domestic infestation rate were reduced from 17.9% to 0.2% (P < 0.01) and from 20.4% to 3%, respectively. Additionally, 399 households were structurally improved. CONCLUSION: The program is still ongoing and, after 14 years of implementation, has built social networks and collaboration between implementers and beneficiaries with a reduction of T. infestans infestation in the intra- and peri-domicile. This reduction, especially inside the household, has enabled access to diagnosis and treatment of the population, with minimal risk of re-infection.

Higher congenital transmission rate of Trypanosoma cruzi associated with family history of congenital transmission.

INTRODUCTION: Congenital transmission (CT) of Trypanosoma cruzi has led to globalization of Chagas disease and its growing relevance as a public health problem. Although the occurrence of CT has been associated with several factors, its mechanisms are still unknown. This study aimed to analyze the geographical and familiar variables of mothers and their association with CT of Chagas disease in a population living in non-endemic areas of Argentina for the last decades. METHODS: We developed a retrospective cohort study in a sample of 2120 mother-child pairs who attended three reference centers in the cities of Buenos Aires, Santa Fe, and Salta between 2002 and 2015. RESULTS: The highest CT rates were observed in children born to Argentinean mothers (10.7%) and in children born to mothers from Buenos Aires (11.7%). Considering the areas of origin of the mothers, those from areas of null-low risk for vector-borne infection had higher CT rates than those from areas of medium-high risk (11.1% vs 8.2%). We also observed a significant intra-familiar "cluster effect," with CT rates of 35.9% in children with an infected sibling, compared to 8.2% in children without infected siblings (RR=4.4 95% CI 2.3-8.4). CONCLUSIONS: The associations observed suggest a higher CT rate in children born to mothers who acquired the infection congenitally, with familiar antecedents, and from areas without the presence of vectors. These observations are considered new epidemiological evidence about Chagas disease in a contemporary urban population, which may contribute to the study of CT and may also be an interesting finding for healthcare professionals.

Higher congenital transmission rate of Trypanosoma cruzi associated with family history of congenital transmission

Abstract INTRODUCTION: Congenital transmission (CT) of Trypanosoma cruzi has led to globalization of Chagas disease and its growing relevance as a public health problem. Although the occurrence of CT has been associated with several factors, its mechanisms are still unknown. This study aimed to analyze the geographical and familiar variables of mothers and their association with CT of Chagas disease in a population living in non-endemic areas of Argentina for the last decades. METHODS: We developed a retrospective cohort study in a sample of 2120 mother-child pairs who attended three reference centers in the cities of Buenos Aires, Santa Fe, and Salta between 2002 and 2015. RESULTS: The highest CT rates were observed in children born to Argentinean mothers (10.7%) and in children born to mothers from Buenos Aires (11.7%). Considering the areas of origin of the mothers, those from areas of null-low risk for vector-borne infection had higher CT rates than those from areas of medium-high risk (11.1% vs 8.2%). We also observed a significant intra-familiar "cluster effect," with CT rates of 35.9% in children with an infected sibling, compared to 8.2% in children without infected siblings (RR=4.4 95% CI 2.3-8.4). CONCLUSIONS: The associations observed suggest a higher CT rate in children born to mothers who acquired the infection congenitally, with familiar antecedents, and from areas without the presence of vectors. These observations are considered new epidemiological evidence about Chagas disease in a contemporary urban population, which may contribute to the study of CT and may also be an interesting finding for healthcare professionals.

Electrocardiographic Abnormalities and Treatment with Benznidazole among Children with Chronic Infection by Trypanosoma cruzi: A Retrospective Cohort Study.

BACKGROUND: Chronic infection by Trypanosoma cruzi could cause heart conduction disturbances. We sought to analyze electrocardiographic abnormalities among children with chronic T. cruzi infection with and without trypanocidal treatment with benznidazole. METHODOLOGY/PRINCIPAL FINDINGS: We studied 111 children 6-16 years of age with asymptomatic chronic T. cruzi infection who were recruited in 1991-1992 in Salta, Argentina. Most children were randomly assigned to benznidazole 5 mg/Kg/day (n = 47) or matching placebo (n = 48) for 60 days. Remaining children (n = 16) received treatment with benznidazole 5 mg/Kg/day open-label. Electrocardiograms were obtained at baseline and in 1995-1996, 1998, 2000 and 2005, and were analyzed using the Buenos Aires method. Among the 94 children with an electrocardiogram at baseline, 8 (8.5%) had electrocardiographic abnormalities, including 4 (4.7%) children with right bundle branch block. Proportion of abnormal electrocardiograms in the full population (n = 111) remained constant over time (media follow-up 8.6 years). Multivariable adjusted prevalence ratios (95% confidence interval [95%CI]) for electrocardiographic abnormalities in 1995-1996, 1998, 2000 and 2005 comparing children treated with benznidazole versus those not treated were 2.76 (0.66, 11.60), 2.33 (0.44, 12.31), 3.06 (0.48, 19.56), and 1.94 (0.33, 11.25), respectively. Among the 86 children with a normal electrocardiogram at baseline, 16 (18.6%) developed electrocardiographic abnormalities during follow-up. The multivariable adjusted hazard ratio for incident electrocardiographic abnormalities comparing children treated with benznidazole versus those not treated was 0.68 (95%CI: 0.25, 1.88). CONCLUSIONS/SIGNIFICANCE: Electrocardiographic abnormalities are frequent among children with chronic T. cruzi infection. Treatment with benznidazole for 60 days may not be associated with less electrocardiographic abnormalities.

Integrated control of Chagas disease for its elimination as public health problem--a review.

Chagas disease or American trypanosomiasis is, together with geohelminths, the neglected disease that causes more loss of years of healthy life due to disability in Latin America. Chagas disease, as determined by the factors and determinants, shows that different contexts require different actions, preventing new cases or reducing the burden of disease. Control strategies must combine two general courses of action including prevention of transmission to prevent the occurrence of new cases (these measures are cost effective), as well as opportune diagnosis and treatment of infected individuals in order to prevent the clinical evolution of the disease and to allow them to recuperate their health. All actions should be implemented as fully as possible and with an integrated way, to maximise the impact. Chagas disease cannot be eradicated due because of the demonstrated existence of infected wild triatomines in permanent contact with domestic cycles and it contributes to the occurrence of at least few new cases. However, it is possible to interrupt the transmission of Trypanosoma cruzi in a large territory and to eliminate Chagas disease as a public health problem with a dramatic reduction of burden of the disease.

Survey of Argentine health researchers on the use of evidence in policymaking.

OBJECTIVE: In this study, Argentine health researchers were surveyed regarding their perceptions of facilitators and barriers to evidence-based policymaking in Argentina, as well as their publication activities, and research environment satisfaction. METHODS: A self-administered online survey was sent to health researchers in Argentina. The survey questions were based on a preceding qualitative study of Argentine health researchers, as well as the scientific literature. RESULTS: Of the 647 researchers that were reached, 226 accessed the survey, for a response rate of 34.9%. Over 80% of researchers surveyed had never been involved in or contributed to decision-making, while over 90% of researchers indicated they would like to be involved in the decision-making process. Decision-maker self-interest was perceived to be the driving factor in the development of health and healthcare policies. Research conducted by a research leader was seen to be the most influential factor in influencing health policy, followed by policy relevance of the research. With respect to their occupational environment, researchers rated highest and most favourably the opportunities available to present, discuss and publish research results and their ability to further their education and training. Argentine researchers surveyed demonstrated a strong interest and willingness to contribute their work and expertise to inform Argentine health policy development. CONCLUSION: Despite Argentina's long scientific tradition, there are relatively few institutionalized linkages between health research results and health policymaking. Based on the results of this study, the disconnect between political decision-making and the health research system, coupled with fewer opportunities for formalized or informal researcher/decision-maker interaction, contribute to the challenges in evidence informing health policymaking in Argentina. Improving personal contact and the building of relationships between researchers and policymakers in Argentina will require taking into account researcher perceptions of policymakers, as highlighted in this study.

Integrated control of Chagas disease for its elimination as public health problem - A Review

Chagas disease or American trypanosomiasis is, together with geohelminths, the neglected disease that causes more loss of years of healthy life due to disability in Latin America. Chagas disease, as determined by the factors and determinants, shows that different contexts require different actions, preventing new cases or reducing the burden of disease. Control strategies must combine two general courses of action including prevention of transmission to prevent the occurrence of new cases (these measures are cost effective), as well as opportune diagnosis and treatment of infected individuals in order to prevent the clinical evolution of the disease and to allow them to recuperate their health. All actions should be implemented as fully as possible and with an integrated way, to maximise the impact. Chagas disease cannot be eradicated due because of the demonstrated existence of infected wild triatomines in permanent contact with domestic cycles and it contributes to the occurrence of at least few new cases. However, it is possible to interrupt the transmission of Trypanosoma cruzi in a large territory and to eliminate Chagas disease as a public health problem with a dramatic reduction of burden of the disease.

Exploring health researchers' perceptions of policymaking in Argentina: a qualitative study.

Much of the published research on evidence-informed health policymaking in low- and middle-income countries has focused on policymakers, overlooking the role of health researchers in the research-to-policy process. Through 20 semi-structured, in-depth qualitative interviews conducted with researchers in Argentina's rural northwest and the capital of Buenos Aires, we explore the perspectives, experiences and attitudes of Argentine health researchers regarding the use and impact of health research in policymaking in Argentina. We find that the researcher, and the researcher's function of generating evidence, is nested within a broader complex system that influences the researcher's interaction with policymaking. This system comprises communities of practice, government departments/civil society organizations, bureaucratic processes and political governance and executive leadership. At the individual level, researcher capacity and determinants of research availability also play a role in contributing to evidence-informed policymaking. In addition, we find a recurrent theme around 'lack of trust' and explore the role of trust within a research system, finding that researchers' distrust towards policymakers and even other researchers are linked inextricably to the sociopolitical history of Argentina, which contributes to shaping researchers' identities in opposition to policymakers. For policymakers, national research councils and funders of national health research systems, this article provides a deeper understanding of researchers' perceptions which can help inform and improve programme design when developing interventions to enhance research utilization and develop equitable and rational health policies. For donors and development agencies interested in health research capacity building and achieving development goals, this research demonstrates a need for investment in building research capacity and training health researchers to interact with the public policy 'world' and enhancing research communications and transferability to decision makers. It also highlights an opportunity to invest in implementation research platforms, such as health policy research and analysis institutions.

Fine-scale genetic structure in populations of the Chagas' disease vector Triatoma infestans (Hemiptera, Reduvidae).

Fine scale patterns of genetic structure and dispersal in Triatoma infestans populations from Argentina was analysed. A total of 314 insects from 22 domestic and peridomestic sites from the locality of San Martín (Capayán department, Catamarca province) were typed for 10 polymorphic microsatellite loci. The results confirm subdivision of T. infestans populations with restricted dispersal among sampling sites and suggest inbreeding and/or stratification within the different domestic and peridomestic structures. Spatial correlation analysis showed that the scale of structuring is approximately of 400 m, indicating that active dispersal would occur within this distance range. It was detected difference in scale of structuring among sexes, with females dispersing over greater distances than males. This study suggests that insecticide treatment and surveillance should be extended within a radius of 400 m around the infested area, which would help to reduce the probability of reinfestation by covering an area of active dispersal. The inferences made from fine-scale spatial genetic structure analyses of T. infestans populations has demonstrated to be important for community-wide control programs, providing a complementary approach to help improve vector control strategies.

Therapy of chagas disease: implications for levels of prevention.

This paper reviews the evidence supporting the use of etiological treatment for Chagas disease that has changed the standard of care for patients with Trypanosoma cruzi infection in the last decades. Implications of this evidence on different levels of prevention as well as gaps in current knowledge are also discussed. In this regard, etiological treatment has shown to be beneficial as an intervention for secondary prevention to successfully cure the infection or to delay, reduce, or prevent the progression to disease, and as primary disease prevention by breaking the chain of transmission. Timely diagnosis during initial stages would allow for the prescription of appropriate therapies mainly in the primary health care system thus improving chances for a better quality of life. Based on current evidence, etiological treatment has to be considered as an essential public health strategy useful to reduce disease burden and to eliminate Chagas disease altogether.

Diagnóstico serológico como indicador del control durante la vigilancia participativa de la transmisión de trypanosoma cruzi en Catamarca, Argentina / Serological diagnosis as a control indicator during the participatory monitoring of the transmission of trypanosoma cruzi in Catamarca, Argentina

INTRODUCCION: El control de la transmisión vectorial de Trypanosoma cruzi en la provincia de Catamarca tuvo un comienzo de gran impacto y su sostenimiento se realizó por un estilo de vigilancia de línea vertical, con lo que se logró un estado avanzado de control. En la década de los 90, debido a las acciones realizadas, se alcanzó el estado de interrupción de la transmisión vectorial y/o transfusional de Trypanosoma cruzi. Esta situación permitió que la provincia fuera catalogada como de mediano riesgo.OBJETIVO: Investigar cuál es el indicador apropiado para señalar el riesgo de reiniciar la transmisión de Trypanosoma cruzi durante la vigilancia participativa.METODOS: En San Isidro y Santa Rosa (Departamento Valle Viejo, Provincia de Catamarca), se realizó un estudio descriptivo retrospectivo y, simultáneamente, otro de corte transversal. Los estudios incluyeron análisis serológicos en niños de 0-14 años, vigilancia mediante búsqueda activa del vector por hora/hombre en las viviendas seleccionadas, análisis parasitológico de los triatominos capturados y encuestas a los pobladores. También hubo talleres comunitarios y capacitación de agentes sanitarios.RESULTADOS: Se determinó una seroprevalencia de 0% en San Isidro y de 0,59% en Santa Rosa. Si bien los indicadores entomológicos registraron infestación intradomicilio del 2%, en cambio, la infestación domiciliaria fue del 10% y 14%, respectivamente, acompañada de una caída importante de las acciones de vigilancia por parte del Estado y de la comunidad.CONCLUSIONES: Es necesaria una reinstalación inmediata de la vigilancia participativa activa para mejorar las medidas de prevención por parte de la comunidad y las acciones de control estatal por parte de los efectores locales, provinciales y nacionales. El Estado debe realizar el ataque químico en las viviendas de acuerdo con las técnicas operativas vigentes y debe intensificar las acciones de vigilancia con evaluaciones hora/hombre.

INTRODUCTION: The control of vectorial transmission of Trypanosoma cruzi in the province of Catamarca had at the beginning a great impact and then was supported by a vertical surveillance. In this way, an advanced control was achieved. The actions undertaken in the 90s led to a state of interruption of vector transmision and/or transfussion of Trypanosoma cruzi. At that time the province was rated as medium risk.OBJECTIVE: To determine the appropiate indicator assessing the risk of transmission of Trypanosoma cruzi being restarted during the surveillance participation.METHODS: A descriptive retrospective study and, simultaneously, a cross-sectional study were conducted in San Isidro and Santa Rosa (Valle Viejo, Province of Catamarca), including serological tests for children aged 0-14 years, monitoring through active search of vector by man/hour method in the selected houses, parasitological study of captured triatomines and surveys to people living there. There were also community workshops and training of health workers.RESULTS: The seroprevalence was 0% in San Isidro and 0.59% in Santa Rosa. While entomological indicators collected indoors recorded 2%, in contrast, house infestation was 10% and 14% respectively, accompanied by a significant drop in the surveillance by the state and community.CONCLUSIONS: It is necessary to immediately re-establish an active participatory monitoring to improve community prevention measures and state surveillance through effectors at local, provincial and national level. The state should make a vector chemical attack at the houses according to current techniques and should intensify surveillance activities with evaluations using the man/hour method.

Diagnóstico serológico como indicador del control durante la vigilancia participativa de la transmisión de trypanosoma cruzi en Catamarca, Argentina / Serological diagnosis as a control indicator during the participatory monitoring of the transmission of trypanosoma cruzi in Catamarca, Argentina

INTRODUCCION: El control de la transmisión vectorial de Trypanosoma cruzi en la provincia de Catamarca tuvo un comienzo de gran impacto y su sostenimiento se realizó por un estilo de vigilancia de línea vertical, con lo que se logró un estado avanzado de control. En la década de los 90, debido a las acciones realizadas, se alcanzó el estado de interrupción de la transmisión vectorial y/o transfusional de Trypanosoma cruzi. Esta situación permitió que la provincia fuera catalogada como de mediano riesgo.OBJETIVO: Investigar cuál es el indicador apropiado para señalar el riesgo de reiniciar la transmisión de Trypanosoma cruzi durante la vigilancia participativa.METODOS: En San Isidro y Santa Rosa (Departamento Valle Viejo, Provincia de Catamarca), se realizó un estudio descriptivo retrospectivo y, simultáneamente, otro de corte transversal. Los estudios incluyeron análisis serológicos en niños de 0-14 años, vigilancia mediante búsqueda activa del vector por hora/hombre en las viviendas seleccionadas, análisis parasitológico de los triatominos capturados y encuestas a los pobladores. También hubo talleres comunitarios y capacitación de agentes sanitarios.RESULTADOS: Se determinó una seroprevalencia de 0% en San Isidro y de 0,59% en Santa Rosa. Si bien los indicadores entomológicos registraron infestación intradomicilio del 2%, en cambio, la infestación domiciliaria fue del 10% y 14%, respectivamente, acompañada de una caída importante de las acciones de vigilancia por parte del Estado y de la comunidad.CONCLUSIONES: Es necesaria una reinstalación inmediata de la vigilancia participativa activa para mejorar las medidas de prevención por parte de la comunidad y las acciones de control estatal por parte de los efectores locales, provinciales y nacionales. El Estado debe realizar el ataque químico en las viviendas de acuerdo con las técnicas operativas vigentes y debe intensificar las acciones de vigilancia con evaluaciones hora/hombre.

INTRODUCTION: The control of vectorial transmission of Trypanosoma cruzi in the province of Catamarca had at the beginning a great impact and then was supported by a vertical surveillance. In this way, an advanced control was achieved. The actions undertaken in the 90’s led to a state of interruption of vector transmision and/or transfussion of Trypanosoma cruzi. At that time the province was rated as medium risk.OBJECTIVE: To determine the appropiate indicator assessing the risk of transmission of Trypanosoma cruzi being restarted during the surveillance participation.METHODS: A descriptive retrospective study and, simultaneously, a cross-sectional study were conducted in San Isidro and Santa Rosa (Valle Viejo, Province of Catamarca), including serological tests for children aged 0-14 years, monitoring through active search of vector by man/hour method in the selected houses, parasitological study of captured triatomines and surveys to people living there. There were also community workshops and training of health workers.RESULTS: The seroprevalence was 0% in San Isidro and 0.59% in Santa Rosa. While entomological indicators collected indoors recorded 2%, in contrast, house infestation was 10% and 14% respectively, accompanied by a significant drop in the surveillance by the state and community.CONCLUSIONS: It is necessary to immediately re-establish an active participatory monitoring to improve community prevention measures and state surveillance through effectors at local, provincial and national level. The state should make a vector chemical attack at the houses according to current techniques and should intensify surveillance activities with evaluations using the man/hour method.

National policy-makers speak out: are researchers giving them what they need?

The objective of this empirical study was to understand the perspectives and attitudes of policy-makers towards the use and impact of research in the health sector in low- and middle-income countries. The study used data from 83 semi-structured, in-depth interviews conducted with purposively selected policy-makers at the national level in Argentina, Egypt, Iran, Malawi, Oman and Singapore. The interviews were structured around an interview guide developed based on existing literature and in consultation with all six country investigators. Transcripts were processed using a thematic-analysis approach. Policy-makers interviewed for this study were unequivocal in their support for health research and the high value they attribute to it. However, they stated that there were structural and informal barriers to research contributing to policy processes, to the contribution research makes to knowledge generally, and to the use of research in health decision-making specifically. Major findings regarding barriers to evidence-based policy-making included poor communication and dissemination, lack of technical capacity in policy processes, as well as the influence of the political context. Policy-makers had a variable understanding of economic analysis, equity and burden of disease measures, and were vague in terms of their use in national decisions. Policy-maker recommendations regarding strategies for facilitating the uptake of research into policy included improving the technical capacity of policy-makers, better packaging of research results, use of social networks, and establishment of fora and clearinghouse functions to help assist in evidence-based policy-making.

Early diagnosis of congenital Trypanosoma cruzi infection, using shed acute phase antigen, in Ushuaia, Tierra del Fuego, Argentina.

Chagas' disease, or American trypanosomiasis, is caused by the protozoan parasite Trypanasoma cruzi. It is estimated that 15,000 new cases of congenital T. cruzi transmission occur in the Americas each year. The aim of this study was to estimate the rate of congenital T. cruzi infection in infants born to infected women living in Ushuaia, Argentina, as well to assess a serologic test using Shed Acute Phase Antigen (SAPA) for a timely diagnosis of congenital infection. The rate of congenital infection among children in the study was 4.4% (3/68). Our results show that for infants younger than 30 days of age, matched blood samples from mother and infant were capable of identifying congenital transmission of infection using an enzyme-linked immunosorbent assay with SAPA. For infants older than 3 months, congenital infection could be ruled out using the same procedure.

Etiological treatment of young women infected with Trypanosoma cruzi, and prevention of congenital transmission.

The objective was to detect Trypanosoma cruzi infection in 32 children in Salta, Argentina, born to 16 chronically infected young women who were treated with benznidazole. Tests were performed to assess the efficacy of treatment after 14 years. At the end of the follow up, 87.5% of the women were non-reactive to EIA tests, 62.5% to IHA and 43.8% to IFA. 62.5% of the women were non-reactive according to two or three serological tests. No infected children were detected among the newborns of mothers treated before their pregnancy.

Etiological treatment of young women infected with Trypanosoma cruzi, and prevention of congenital transmission / Tratamento etiológico de mulheres jovens infectadas com Trypanosoma cruzi e prevenção da transmissão congênita

The objective was to detect Trypanosoma cruzi infection in 32 children in Salta, Argentina, born to 16 chronically infected young women who were treated with benznidazole. Tests were performed to assess the efficacy of treatment after 14 years. At the end of the follow up, 87.5 percent of the women were non-reactive to EIA tests, 62.5 percent to IHA and 43.8 percent to IFA. 62.5 percent of the women were non-reactive according to two or three serological tests. No infected children were detected among the newborns of mothers treated before their pregnancy.

O objetivo foi detectar a infecção do Trypanosoma cruzi em 32 crianças nacidas de 16 jovens mulheres cronicamente infectadas e tratadas com benzinadol, em Salta, Argentina. Testes foram feitos para avaliar a eficácia após 14 anos do tratamento. Ao final do seguimento 87.5 por cento das mulheres foram não reativas ao EIA, 62.5 por cento ao IHA e 43.8 por cento ao IFA. 62.5 por cento das mulheres foram não reativas de acordo a 3 ou 2 testes serológicos. Nenhuma criança infectada foi detectada entre os recém-nascidos de mães tratadas antes da gravidez.

Therapy, diagnosis and prognosis of chronic Chagas disease: insight gained in Argentina.

The purpose of this review is to describe research findings regarding chronic Chagas disease in Argentina that have changed the standards of care for patients with Trypanosoma cruzi infection. Indirect techniques (serological tests) are still the main tools for the primary diagnosis of infection in the chronic phase, but polymerase chain reaction has been shown to be promising. The prognosis of patients with heart failure or advanced stages of chagasic cardiomyopathy is poor, but a timely diagnosis during the initial stages of the disease would allow for prescription of appropriate therapies to offer a better quality of life. Treatment of T. cruzi infection is beneficial as secondary prevention to successfully cure the infection or to delay, reduce or prevent the progression to disease and as primary disease prevention by breaking the chain of transmission. Current recommendations have placed the bulk of the diagnostic and treatment responsibility on the Primary Health Care System. Overall, the current research priorities with respect to Chagas disease should be targeted towards (i) the production of new drugs that would provide a shorter treatment course with fewer side effects; (ii) the development of new tools to confirm cure after a full course of treatment during the chronic phase and (iii) biomarkers to identify patients with a high risk of developing diseases.

Therapy, diagnosis and prognosis of chronic Chagas disease: insight gained in Argentina

The purpose of this review is to describe research findings regarding chronic Chagas disease in Argentina that have changed the standards of care for patients with Trypanosoma cruzi infection. Indirect techniques (serological tests) are still the main tools for the primary diagnosis of infection in the chronic phase, but polymerase chain reaction has been shown to be promising. The prognosis of patients with heart failure or advanced stages of chagasic cardiomyopathy is poor, but a timely diagnosis during the initial stages of the disease would allow for prescription of appropriate therapies to offer a better quality of life. Treatment of T. cruzi infection is beneficial as secondary prevention to successfully cure the infection or to delay, reduce or prevent the progression to disease and as primary disease prevention by breaking the chain of transmission. Current recommendations have placed the bulk of the diagnostic and treatment responsibility on the Primary Health Care System. Overall, the current research priorities with respect to Chagas disease should be targeted towards (i) the production of new drugs that would provide a shorter treatment course with fewer side effects; (ii) the development of new tools to confirm cure after a full course of treatment during the chronic phase and (iii) biomarkers to identify patients with a high risk of developing diseases.

Macrogeographic and microgeographic genetic structure of the Chagas' disease vector Triatoma infestans (Hemiptera: Reduviidae) from Catamarca, Argentina.

The genetic structure in populations of the Chagas' disease vector Triatoma infestans from six localities belonging to areas under the same insecticide treatment conditions of Catamarca province (Argentina) was examined at macrogeographical and microgeographical scales. A total of 238 insects were typed for 10 polymorphic microsatellite loci. The average observed and expected heterozygosities ranged from 0.319 to 0.549 and from 0.389 to 0.689, respectively. The present results confirm that populations of T. infestans are highly structured. Spatial genetic structure was detectable at macrogeographical and microgeographical levels. Comparisons of the levels of genetic variability between two temporal samples were carried out to assess the impact of the insecticide treatment. The genetic diversity of the population was not significantly affected after insecticide use since different genetic parameters (allele number, observed and expected heterozygosities) remained stable. However, loss of low frequency alleles and not previously found alleles were detected. The effective population size (N(e)) estimated was substantially lower in the second temporal sample than in the first; nevertheless, it is possible that the size of the remnant population after insecticide treatment was still large enough to retain the genetic diversity. Very few individuals did not belong to the local T. infestans populations as determined by assignment analyses, suggesting a low level of immigration in the population. The results of the assignment and first-generation migrant tests suggest male-biased dispersal at microgeographical level.

Sustainable vector control and management of Chagas disease in the Gran Chaco, Argentina.

Chagas disease remains a serious obstacle to health and economic development in Latin America, especially for the rural poor. We report the long-term effects of interventions in rural villages in northern Argentina during 1984-2006. Two community-wide campaigns of residual insecticide spraying immediately and strongly reduced domestic infestation and infection with Trypanosoma cruzi in Triatoma infestans bugs and dogs and more gradually reduced the seroprevalence of children <15 years of age. Because no effective surveillance and control actions followed the first campaign in 1985, transmission resurged in 2-3 years. Renewed interventions in 1992 followed by sustained, supervised, community-based vector control largely suppressed the reestablishment of domestic bug colonies and finally led to the interruption of local human T. cruzi transmission. Human incidence of infection was nearly an order of magnitude higher in peripheral rural areas under pulsed, unsupervised, community-based interventions, where human transmission became apparent in 2000. The sustained, supervised, community-based strategy nearly interrupted domestic transmission to dogs but did not eliminate T. infestans despite the absence of pyrethroid-insecticide resistance. T. infestans persisted in part because of the lack of major changes in housing construction and quality. Sustained community participation grew out of establishing a trusted relationship with the affected communities and the local schools. The process included health promotion and community mobilization, motivation, and supervision in close cooperation with locally nominated leaders.