The long-term impact of an Ecohealth intervention: Entomological data suggest the interruption of Chagas disease transmission in southeastern Guatemala.

Triatoma dimidiata is the main vector of Chagas disease in southern Mexico, Central America and northern South America. As a native vector, it moves readily among domestic, peri­domestic and sylvatic environments, making it difficult to control only using insecticide as this requires regular application, and re-infestation frequently occurs. Other social innovation alternatives such as those based on Ecohealth principles can be used to tackle the dynamics of the disease in an integral way. We asked whether an Ecohealth intervention, implemented beginning in 2001 in a highly infested village, 41.8%, in southeastern Guatemala, was sustainable in the long term. This intervention included initial insecticide treatments, followed by making low-cost house improvements to eliminate transmission risk factors such as repairing cracked walls, covering dirt floors with a cement-like substance and moving domestic animals outside. We assessed the long-term sustainability through entomological and house condition surveys, as well as an analysis of community satisfaction. We found over a 19-year period, infestation with T. dimidiata was reduced to 2.2% and maintained at a level below the level (8%) where vector transmission is unlikely. This long-term maintenance of low infestation coincided with a large proportion of villagers (88.6%) improving their houses and completing other aspects of the Ecohealth approach to maintain the village at low risk for Chagas transmission. There was unanimous satisfaction among the villagers with their houses, following improvements using the Ecohealth method, which likely played a role in the long-term persistence of the modifications. Although the infestation has remained low, 11 years following the last intervention and as the population grew there has been an increase in the proportion of "at-risk" houses, to 33%, pointing out the necessity of maintaining vigilance. The Ecohealth approach is a low-cost, sustainable approach for the long-term control of vector-borne Chagas disease. We recommend this approach including ongoing community monitoring and institutional response for the long-term, integrated control of Chagas disease.

A multidisciplinary, collaborative, inter-agency and comprehensive approach for the control of Chagas Disease as a public health problem in Guatemala.

The Pan American Health Organization (PAHO) has defined Chagas Disease hotspots in Central America associated with the vector Triatoma spp. Triatoma dimidiata is a native vector adapted to multiple environments, including intra-domestic and peri-domestic habitats. A multi-institutional project named "Alliances for the elimination of Chagas in Central America" was created to help reduce the incidence of the disease in the region. Activities performed in the field as part of the project included aspects of vector surveillance and control, improvement of houses, diagnosis and treatment of individuals, health promotion, training of human resources and identification of access barriers to diagnosis and treatment. As a base line study, eleven villages, comprised of 1,572 households, were entomologically evaluated (83.4% overall participation); five were found to have very high infestation rates (>20%), three had high infestation rates (8-20%) and three had low-infestation rates (<8%), coinciding with the category of infestation-risk of the houses within each village. Serological tests were carried out in 812 people (>80% participation) in two of the 11 villages and none of the 128 children tested, less than 5 years of age, were positive for Trypanosoma cruzi infection. Community participation in all the activities was high (>70%). The collaboration between several subnational, national, and international institutions, each with specific roles, promoted community participation in the activities of vector control and patient care, thus, establishing a baseline to continue implementing and monitoring project progress.

Insights from a comprehensive study of Trypanosoma cruzi: A new mitochondrial clade restricted to North and Central America and genetic structure of TcI in the region.

More than 100 years since the first description of Chagas Disease and with over 29,000 new cases annually due to vector transmission (in 2010), American Trypanosomiasis remains a Neglected Tropical Disease (NTD). This study presents the most comprehensive Trypanosoma cruzi sampling in terms of geographic locations and triatomine species analyzed to date and includes both nuclear and mitochondrial genomes. This addresses the gap of information from North and Central America. We incorporate new and previously published DNA sequence data from two mitochondrial genes, Cytochrome oxidase II (COII) and NADH dehydrogenase subunit 1 (ND1). These T. cruzi samples were collected over a broad geographic range including 111 parasite DNA samples extracted from triatomines newly collected across North and Central America, all of which were infected with T. cruzi in their natural environment. In addition, we present parasite reduced representation (Restriction site Associated DNA markers, RAD-tag) genomic nuclear data combined with the mitochondrial gene sequences for a subset of the triatomines (27 specimens) collected from Guatemala and El Salvador. Our mitochondrial phylogenetic reconstruction revealed two of the major mitochondrial lineages circulating across North and Central America, as well as the first ever mitochondrial data for TcBat from a triatomine collected in Central America. Our data also show that within mtTcIII, North and Central America represent an independent, distinct clade from South America, named here as mtTcIIINA-CA, geographically restricted to North and Central America. Lastly, the most frequent lineage detected across North and Central America, mtTcI, was also an independent, distinct clade from South America, noted as mtTcINA-CA. Furthermore, nuclear genome data based on Single Nucleotide Polymorphism (SNP) showed genetic structure of lineage TcI from specimens collected in Guatemala and El Salvador supporting the hypothesis that genetic diversity at a local scale has a geographical component. Our multiscale analysis contributes to the understanding of the independent and distinct evolution of T. cruzi lineages in North and Central America regions.

Integrated vector control of Chagas disease in Guatemala: a case of social innovation in health.

BACKGROUND: Improved access to health care and quality of services require integrated efforts and innovations, including community empowerment and participation in transformation processes. Chagas disease is a neglected tropical disease that is generally controlled by insecticide spraying. To achieve community empowerment in a health program, actions for social innovations may include: community-based research, interdisciplinary and intersectoral participation, community perception of direct benefits and participation in health or environmental improvements. The aim of this study was to describe and analyze the processes by which an interdisciplinary team, in collaboration with communities of Comapa, Guatemala, developed an effective solution to address the risk for Chagas disease. METHODS: A qualitative study involving interviews semi-structured and direct observation was conducted using a case study approach to describe and understand the community-based research and intervention process developed by researchers from the Laboratory of Applied Entomology and Parasitology of the Universidad de San Carlos of Guatemala (Laboratorio de Entomologia y Parasitologia Aplicada). Nine interviews were conducted with the investigators, innovators, members of the community in which the intervention had been implemented. NVivo software (version 12) was used for the emergent coding and analysis of the interviews. RESULTS: Processes of social transformation were evident within households, and the communities that transcended the mere improvement of walls and floors. New social dynamics that favored the household economy and conditions of hygiene and home care that positively impacted the health of the community. We describe how the integration of criteria of social innovation into a home improvement strategy for Chagas disease control, can generate processes of transformation in health by considering sociocultural conditions, encouraging dialogue between public health approaches and traditional practices. We identify and discuss processes for Social Innovations in Health and identify their potential in improving community health in Latin America. CONCLUSIONS: When social innovation criteria are included in a health control initiative, the community-based research and the interdisciplinary and intersectoral participation facilitate the implementation of the control strategy, the perceived benefits by the community and its empowerment to sustain and share the strategy. The case study provided understanding of the intersectoral and interdisciplinary dynamics in particular contexts, and documented the relevance of innovation criteria in health processes.

Efecto de la educación comunitaria para control integrado del Triatoma Dimidiata (Hemiptera: Reduviidae) / EEffect of community education in an integrate control for Triatoma dimidiata (Hemiptera: Reduviidae) / EEffect of community education in an integrate control for Triatoma dimidiata (Hemiptera: Reduviidae)

Introduction: The Mesoamerican endemic specieTriatoma dimidiata is the main vector of Chagas disease in Central America, after the elimination of an introduced vector Rhodnius prolixus. The traditional method of vector control using insecticides results in reinfestation. An integrated Ecohealth approach, including education, house improvements and domestic animal management was shown effective for long-term control ofT. dimidiata, and it was applied in several villages in Guatemala. Objective: To evaluate the changes in community practices after an Ecohealth intervention in La Prensa, Olopa Chiquimula. Methods: Through three surveys, we measured risk factors associated withT. dimidiatainfestation, the infestation index, blood sources of T. dimidiata, the presence of Trypanosoma cruzi were analyzed using PCR. Statistics analysis included Wilcoxon signed-rank tests, Mc-Nemar test, Chi-square test and Fisher exact test to compare the surveys. Results: Over the years, risk factors associated with the presence of T. dimidiata and population density of the vector were observed. We found a decrease in consumption of human blood and the parasite in the vector population. However, we found the consumption of bird blood meal increased Conclusions: Our results provide evidence that an ecohealth approach for an endemic Chagas vector has impact on reducing vector-human contact, possibly by influencing people's behavior. Increasing the community knowledge about these risk factors can be an effective strategy to further reduce the risk of house reinfestation and Chagas transmission(AU)

Introducción: La especie endémica mesoamericana Triatoma dimidiata es el vector principal de la enfermedad de Chagas en América Central, después de la eliminación de un vector introducido Rhodnius prolixus. El método tradicional de control de vectores que utiliza insecticidas resulta en reinfestación. Se demostró que un enfoque integrado de ecosalud, que incluye la educación, mejorías en el hogar y manejo de animales domésticos, es efectivo para el control a largo plazo del T. dimidiata, y se aplicó en varias aldeas de Guatemala. Objetivo: evaluar los cambios en las prácticas comunitarias después de una intervención de ecosalud en La Prensa, Olopa Chiquimula. Métodos: a través de tres encuestas, se midieron los factores de riesgo asociados con la infestación de T. dimidiata, el índice de infestación, las fuentes sanguíneas de T. dimidiata y la presencia de Trypanosoma cruzi. Estas encuestas se analizaron mediante PCR. El análisis estadístico incluyó pruebas de Wilcoxon de rango con signo, la prueba de Mc-Nemar, la prueba de Chi-cuadrado y la prueba exacta de Fisher para comparar las encuestas. Resultados: A lo largo de los años, se observaron factores de riesgo asociados con la presencia de T. dimidiata y la densidad de población del vector. Encontramos una disminución del parásito en la población de vectores y en el consumo de sangre humana. Sin embargo, encontramos que aumentó el consumo de harina de sangre de aves. Conclusiones: Nuestros resultados proporcionan evidencia de que un enfoque de ecosalud para un vector de Chagas endémico impacta en la reducción del contacto vector-humano, posiblemente al influir en el comportamiento de las personas. Aumentar el conocimiento de la comunidad sobre estos factores de riesgo puede ser una estrategia efectiva para reducir aun más el riesgo de reinfestación en la casa y la transmisión de Chagas(AU)

Description of Triatomahuehuetenanguensis sp. n., a potential Chagas disease vector (Hemiptera, Reduviidae, Triatominae).

A new species of the genus Triatoma Laporte, 1832 (Hemiptera, Reduviidae) is described based on specimens collected in the department of Huehuetenango, Guatemala. Triatomahuehuetenanguensis sp. n. is closely related to T.dimidiata (Latreille, 1811), with the following main morphological differences: lighter color; smaller overall size, including head length; and width and length of the pronotum. Natural Trypanosomacruzi (Chagas, 1909) infection, coupled with its presence in domestic habitats, makes this species a potentially important vector of Trypanosomacruzi in Guatemala.

Implementation science: Epidemiology and feeding profiles of the Chagas vector Triatoma dimidiata prior to Ecohealth intervention for three locations in Central America.

The Ecohealth strategy is a multidisciplinary data-driven approach used to improve the quality of people's lives in Chagas disease endemic areas, such as regions of Central America. Chagas is a vector-borne disease caused by the parasite Trypanosoma cruzi. In Central America, the main vector is Triatoma dimidiata. Because successful implementation of the Ecohealth approach reduced home infestation in Jutiapa department, Guatemala, it was scaled-up to three localities, one in each of three Central American countries (Texistepeque, El Salvador; San Marcos de la Sierra, Honduras and Olopa, Guatemala). As a basis for the house improvement phase of the Ecohealth program, we determined if the localities differ in the role of sylvatic, synanthropic and domestic animals in the Chagas transmission cycle by measuring entomological indices, blood meal sources and parasite infection from vectors collected in and around houses. The Polymerase Chain Reaction (PCR) with taxa specific primers to detect both, blood sources and parasite infection, was used to assess 71 T. dimidiata from Texistepeque, 84 from San Marcos de la Sierra and 568 from Olopa. Our results show that infestation (12.98%) and colonization (8.95%) indices were highest in Olopa; whereas T. cruzi prevalence was higher in Texistepeque and San Marcos de la Sierra (>40%) than Olopa (8%). The blood meal source profiles showed that in Olopa, opossum might be important in linking the sylvatic and domestic Chagas transmission cycle, whereas in San Marcos de la Sierra dogs play a major role in maintaining domestic transmission. For Texistepeque, bird was the major blood meal source followed by human. When examining the different life stages, we found that in Olopa, the proportion bugs infected with T. cruzi is higher in adults than nymphs. These findings highlight the importance of location-based recommendations for decreasing human-vector contact in the control of Chagas disease.

The role of natural selection in shaping genetic variation in a promising Chagas disease drug target: Trypanosoma cruzi trans-sialidase.

Rational drug design creates innovative therapeutics based on knowledge of the biological target to provide more effective and responsible therapeutics. Chagas disease, endemic throughout Latin America, is caused by Trypanosoma cruzi, a protozoan parasite. Current therapeutics are problematic with widespread calls for new approaches. Researchers are using rational drug design for Chagas disease and one target receiving considerable attention is the T. cruzi trans-sialidase protein (TcTS). In T. cruzi, trans-sialidase catalyzes the transfer of sialic acid from a mammalian host to coat the parasite surface membrane and avoid immuno-detection. However, the role of TcTS in pathology variance among and within genetic variants of the parasite is not well understood despite numerous studies. Previous studies reported the crystalline structure of TcTS and the TS protein structure in other trypanosomes where the enzyme is often inactive. However, no study has examined the role of natural selection in genetic variation in TcTS. To understand the role of natural selection in TcTS DNA sequence and protein variation, we examined a 471 bp portion of the TcTS gene from 48 T. cruzi samples isolated from insect vectors. Because there may be multiple parasite genotypes infecting one insect and there are multiple copies of TcTS per parasite genome, all 48 sequences had multiple polymorphic bases. To resolve these polymorphisms, we examined cloned sequences from two insect vectors. The data are analyzed to understand the role of natural selection in shaping genetic variation in TcTS and interpreted in light of the possible role of TcTS as a drug target. The analysis highlights negative or purifying selection on three amino acids previously shown to be important in TcTS transfer activity. One amino acid in particular, Tyr342, is a strong candidate for a drug target because it is under negative selection and amino acid substitutions inactivate TcTS transfer activity. AUTHOR SUMMARY: Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and transmitted to humans and other mammals primarily by Triatomine insects. Being endemic in many South and Central American countries and affecting millions of people the need for new more effective and safe therapies is evident. Here, we examine genetic variation and natural selection on DNA (471 bp) and amino acid (157 aa) sequence data of the T. cruzi trans-sialdiase (TcTS) protein, often suggested as a candidate for rational drug design. In our surveyed region of the protein there were five amino acid residues that have been shown to be integral to the function of TcTS. We found that three were under strong negative selection making them ideal candidates for drug design; however, one was under balancing selection and should be avoided as a drug target. Our study provides new information into identifying potential targets for a new Chagas drug.

The diversity of the Chagas parasite, Trypanosoma cruzi, infecting the main Central American vector, Triatoma dimidiata, from Mexico to Colombia.

Little is known about the strains of Trypanosoma cruzi circulating in Central America and specifically in the most important vector in this region, Triatoma dimidiata. Approximately six million people are infected with T. cruzi, the causative agent of Chagas disease, which has the greatest negative economic impact and is responsible for ~12,000 deaths annually in Latin America. By international consensus, strains of T. cruzi are divided into six monophyletic clades called discrete typing units (DTUs TcI-VI) and a seventh DTU first identified in bats called TcBat. TcI shows the greatest geographic range and diversity. Identifying strains present and diversity within these strains is important as different strains and their genotypes may cause different pathologies and may circulate in different localities and transmission cycles, thus impacting control efforts, treatment and vaccine development. To determine parasite strains present in T. dimidiata across its geographic range from Mexico to Colombia, we isolated abdominal DNA from T. dimidiata and determined which specimens were infected with T. cruzi by PCR. Strains from infected insects were determined by comparing the sequence of the 18S rDNA and the spliced-leader intergenic region to typed strains in GenBank. Two DTUs were found: 94% of infected T. dimidiata contained TcI and 6% contained TcIV. TcI exhibited high genetic diversity. Geographic structure of TcI haplotypes was evident by Principal Component and Median-Joining Network analyses as well as a significant result in the Mantel test, indicating isolation by distance. There was little evidence of association with TcI haplotypes and host/vector or ecotope. This study provides new information about the strains circulating in the most important Chagas vector in Central America and reveals considerable variability within TcI as well as geographic structuring at this large geographic scale. The lack of association with particular vectors/hosts or ecotopes suggests the parasites are moving among vectors/hosts and ecotopes therefore a comprehensive approach, such as the Ecohealth approach that makes houses refractory to the vectors will be needed to successfully halt transmission of Chagas disease.

The Role of Gender in Chagas Disease Prevention and Control in Honduras: An Analysis of Communication and Collaboration Networks.

In Honduras, where Chagas disease is a serious health and environmental concern, prevention measures face the challenge of achieving widespread and long-term sustainable adoption by communities. The article integrates social network analysis and a gender-sensitive approach to understand the role of men and women in the implementation of a community-level intervention, based on the adoption of housing improvements to reduce the presence of the insect vector. A total of 108 people in the community of El Salitre were interviewed. Data were collected on socio-demographic characteristics, participation in project activities, communication and collaboration networks related to Chagas disease prevention, knowledge of Chagas disease, and adoption of housing improvements techniques. Communication mostly occurred between the same gender individuals and was associated with knowledge of Chagas disease. Socioeconomic status, Chagas disease knowledge, and collaboration with men were associated with women adopting housing improvements. For men, however, participation in project activities, formal education, and collaboration with women were associated with adoption. These findings suggest that men and women were driven by distinct concerns, interests, and motivations when adopting new Chagas disease prevention strategies. Participatory community interventions that seek to generate health knowledge and foster collaborations to reduce health risk should address gender differences.

Ecohealth interventions limit triatomine reinfestation following insecticide spraying in La Brea, Guatemala.

In this study, we evaluate the effect of participatory Ecohealth interventions on domestic reinfestation of the Chagas disease vector Triatoma dimidiata after village-wide suppression of the vector population using a residual insecticide. The study was conducted in the rural community of La Brea, Guatemala between 2002 and 2009 where vector infestation was analyzed within a spatial data framework based on entomological and socio-economic surveys of homesteads within the village. Participatory interventions focused on community awareness and low-cost home improvements using local materials to limit areas of refuge and alternative blood meals for the vector within the home, and potential shelter for the vector outside the home. As a result, domestic infestation was maintained at ≤ 3% and peridomestic infestation at ≤ 2% for 5 years beyond the last insecticide spraying, in sharp contrast to the rapid reinfestation experienced in earlier insecticide only interventions.

Environmental determinants of the distribution of Chagas disease vectors in south-eastern Guatemala.

The associations between the presence of triatomines and environmental variables were studied using correlation analysis and logistic regression models for a sample of villages in the south-eastern provinces of Guatemala. Information on the presence of Triatoma dimidiata, T. nitida and Rhodnius prolixus came from entomological surveys carried out by the Ministry of Health of Guatemala as part of its vector control programme. Environmental information for each village was extracted from digital thematic maps developed by the Ministry of Agriculture. The presence of T. nitida was found to be significantly associated with the average minimum temperature. The odds of presence of T. nitida in a village decreased as the average minimum temperature increased. T. nitida exists at altitudes above 1000 m above sea level in temperate regions. The presence of R. prolixus showed a significant positive association with maximum absolute temperature and relative humidity. The logistic regression model for R. prolixus showed a good fit and predicted suitable habitats in the provinces of Chiquimula, Zacapa and Jalapa, which agrees with the known distribution of the species. Habitat partitioning between R. prolixus and T. dimidiata is suggested by their significant and opposite associations with maximum absolute temperature. Improved models to predict suitable habitats for T. dimidiata hold promise for spatial targeting of integrated vector management.

Habitats, dispersion and invasion of sylvatic Triatoma dimidiata (Hemiptera: Reduviidae: Triatominae) in Petén, Guatemala.

Dispersion and invasion capacity of sylvatic populations of Triatoma dimidiata (Latreille) were investigated during 14 mo by means of experimental chicken coops installed in a nature reserve within the Maya Biosphere, Petén, Guatemala. In addition, palm trees, underground archeological holes (chultunes) and piles of limestones within the forest were inspected as potential sylvatic habitats of T. dimidiata. From the three types of sylvatic habitats we inspected, all served as shelter and breeding sites for T dimidiata. The natural infection of these bugs (n = 72) with Trypanosoma cruzi (Chagas) was high (25%) and represent a risk for humans who colonize the forest. T. dimidiata quickly invaded the experimental chicken coops installed in the primary forest, albeit at very low densities. However, only one adult bug was encountered in the chicken coops installed in a secondary forest. Dispersal of adult T. dimidiata was most apparent at the end of the dry season. Overall, our results indicate a potential risk for invasion by sylvatic T. dimidiata of domestic environments in this area, with a risk of T. cruzi transmission to humans. We suggest that a system of community-based surveillance should be developed to detect new infestations and organize prompt treatment of any new cases of acute Chagas disease that may result.