Chagas disease (CD) still imposes a heavy burden on most Latin American countries. Vector-borne and mother-to-child transmission cause several thousand new infections per year, and at least 5 million people carry Trypanosoma cruzi. Access to diagnosis and medical care, however, is far from universal. Starting in the 1990s, CD-endemic countries and the Pan American Health Organization-World Health Organization (PAHO-WHO) launched a series of multinational initiatives for CD control-surveillance. An overview of the initiatives’ aims, achievements, and challenges reveals some key common themes that we discuss here in the context of the WHO 2030 goals for CD. Transmission of T. cruzi via blood transfusion and organ transplantation is effectively under control. T. cruzi, however, is a zoonotic pathogen with 100+ vector species widely spread across the Americas; interrupting vector-borne transmission seems therefore unfeasible. Stronger surveillance systems are, and will continue to be, needed to monitor and control CD. Prevention of vertical transmission demands boosting current efforts to screen pregnant and childbearing-aged women. Finally, integral patient care is a critical unmet need in most countries. The decades-long experience of the initiatives, in sum, hints at the practical impossibility of interrupting vector-borne T. cruzi transmission in the Americas. The concept of disease control seems to provide a more realistic description of what can in effect be achieved by 2030.

Panstrongylus geniculatus (Latreille, 1811) is the triatomine with the largest geographic distribution in Latin America. It has been reported in 18 countries from southern Mexico to northern Argentina, including the Caribbean islands. Although most reports indicate that P. geniculatus has wild habitats, this species has intrusive habits regarding human dwellings mainly located in intermediate deforested areas. It is attracted by artificial light from urban and rural buildings, raising the risk of transmission of Trypanosoma cruzi. Despite the wide body of published information on P. geniculatus, many knowledge gaps exist about its biology and epidemiological potential. For this reason, we analysed the literature for P. geniculatus in Scopus, PubMed, Scielo, Google Scholar and the BibTriv3.0 databases to update existing knowledge and provide better information on its geographic distribution, life cycle, genetic diversity, evidence of intrusion and domiciliation, vector-related circulating discrete taxonomic units, possible role in oral T. cruzi transmission, and the effect of climate change on its biology and epidemiology.

Resumen Hay poca información sobre la inmunidad innata de los triatominos contra Trypanosoma rangeli, un parásito infeccioso para el humano, aunque no patógeno, y T. cruzi, el agente causal de la enfermedad de Chagas. En este trabajo se buscó llenar ese vacío mediante el estudio de la actividad tripanolítica in vitro de la hemolinfa de insectos no infectados con T. rangeli o T. cruzi. Se examinaron ocho especies de triatominos: Rhodnius prolixus, R. robustus, R. colombiensis, R. pallescens, R. pictipes, Triatoma dimidiata, T. maculata, y Panstrongylus geniculatus. La hemolinfa de las colonias de laboratorio de R. prolixus y R. robustus presentó una fuerte actividad tripanolítica durante las primeras 14 horas de incubación con los parásitos, evidenciando 81 y 90 % de lisis para los genotipos C y E de T. rangeli y 95 % para la unidad taxonómica discreta (DTU) de TcII, 94 % para TcV, 96% para TcVI, 94 % para Tcbat y 90 % para Tcmarinkellei. No se detectó lisis a las 14 ni a las 24 horas de incubación de los parásitos con las hemolinfas de colonias de laboratorio de R. pictipes, R. pallescens, P. geniculatus y T. maculata. Se registraron resultados idénticos (ausencia de lisis) con la hemolinfa de colonias de laboratorio de R. colombiensis y T. dimidiata y de especímenes capturados en ambientes selváticos. La actividad lítica de la hemolinfa fue similar en cultivos recientes de TcII (95 % de lisis) y en aquellos mantenidos por periodos prolongados (96 % de lisis). La actividad lítica de la hemolinfa de R. prolixus fue similar en ninfas, machos y hembras y en insectos alimentados con sangre de gallina o sangre de ratón. Este es el primer estudio comparativo de la actividad tripanolítica en la hemolinfa de diferentes especies de triatominos contra genotipos de T. rangeli y T. cruzi. Aunque la estructura química de los factores líticos, así como los mecanismos que determinan su expresión, aún no se han establecido completamente, su identificación permitirá comprender mejor la inmunidad innata de los triatominos y su papel en la trasmisión de los tripanosomas.

Abstract There is limited information about the innate immunity of triatomines against Trypanosoma rangeli, an infectious, non-pathogenic human parasite, and T. cruzi, the causative agent of Chagas' disease. This study aimed at addressing this gap by studying the in vitro trypanolytic hemolymph activity from insects not infected by T. rangeli or T. cruzi. Eight triatomine species were examined including Rhodnius prolixus, R. robustus, R. colombiensis, R. pallescens, R. pictipes, Triatoma dimidiata, T. maculata, and Panstrongylus geniculatus. The hemolymph of R. prolixus and R. robustus laboratory colonies demonstrated strong trypanolytic activity during the first 14 hours of parasite incubation with 81% lysis for the T. rangeli C genotype, 90% for the E genotype, 95% for T. cruzi discrete taxonomic unit (DTU) TcII, 94% for TcV, 96% for TcVI, 94% for Tcbat, and 90% for Tcmarinkellei. No lysis activity was detected 14 or 24 hours after parasite incubation with the hemolymph of insects from R. pictipes R. pallescens, P. geniculatus, and T. maculata colonies. Identical results (absence of lysis) were observed using hemolymph from R. colombiensis and T. dimidiata laboratory colonies and specimens captured in sylvatic environments. The hemolymph lytic activity against recently obtained cultures (95% decrease in live parasite count) and long-term T. cruzi TcII ones (96% decrease) was similar. Lytic activity was similar in hemolymph from R. prolixus nymphs, males and females and insects fed on chicken or mouse blood. This is the first comparative study of the trypanolytic activity of hemolymph from different triatomine species against T. rangeli and T. cruzi genotypes. Although the chemical structures of such lysis factors and the mechanisms determining their expression have not been fully determined, their identification furthers our understanding of triatomines' innate immunity and their role in Trypanosoma transmission.

Abstract This work was carried out with the indigenous community of the Mirití-Paraná river, a short tributary of the Caquetá (Japura) river, located northwest of Colombia’s Amazon basin. I set forth the therapeutic journey of Enio Yukuna, an old man who had a traffic accident and, when telling the story of what happened, recalled that his misfortune began some decades ago when he went tapir hunting in a clay lick. His story and journey are relevant because he talks about how he conceives the land, cosmopolitics, the ontological processes to learn shamanism, and of the interaction of biomedicine and the Western medical system. In doing so, he speaks explicitly of the typical healing processes that take place in his region, going through shamans of different ethnic groups and varied knowledge that behave in different ways vis-à-vis his affliction. He also talks about gender complementarity with his wife and about prejudice against youth migration, and finally tells how he was sent to Bogota to be treated for his ailment. It is an incredible story that gives us the opportunity to explore the multiple Amazonic universes regarding a person’s health.

Resumen Este trabajo se desarrolló con las comunidades indígenas del río Mirití-Paraná, un pequeño afluente del río Caquetá (Japura), en el noroccidente de la cuenca amazónica en Colombia. Lo que presento a continuación es el itinerario terapéutico de Enio Yukuna, un hombre mayor que sufrió un accidente de tránsito y que al momento de relatar lo que le había ocurrido se remontó en su memoria varias décadas atrás para explicar que el principio de su mal se dio cuando fue a cazar a una danta (tapir) en un salado. Su itinerario y la narración del suceso es pertinente, pues habla de la forma en que se concibe el territorio, la cosmopolítica, los procesos ontológicos para aprender el chamanismo y también de la interacción con la biomedicina y el sistema médico occidental. Así, este hombre hace explícitos los procesos propios de curación que se dan en su área geográfica, pasando por chamanes de diferentes etnias y variados conocimientos y que se comportan de manera distinta ante su mal. Habla también de la complementariedad de género con su mujer y de los prejuicios hacia la migración de los jóvenes, y finalmente cuenta cómo fue remitido a Bogotá para ser atendido por su dolencia. Es una narración de gran riqueza y complejidad que nos da la posibilidad de navegar por los diversos universos amazónicos con relación a la salud de un individuo.

Rhodnius prolixus, a blood-sucking triatomine with domiciliary anthropophilic habits, is the main vector of Chagas disease. The current paradigm of Trypanosoma cruzi transmission in Columbia includes a sylvatic and domiciliary cycle co-existing with domestic and sylvatic populations of reservoirs. The aim of this study is to evaluate the population densities and relative abundance of triatomines and mammals that may be involved in the sylvatic cycle of Chagas disease to clarify the epidemiological scenario in an endemic area in the province of Casanare. Insect vectors on Attalea butyracea palms were captured using both manual searches and bait traps. The capture of mammals was performed using Sherman and Tomahawk traps. We report an infestation index of 88.5% in 148 palms and an index of T. cruzi natural infection of 60.2% in 269 dissected insects and 11.9% in 160 captured mammals. High population densities of triatomines were observed in the sylvatic environment and there was a high relative abundance of reservoirs in the area, suggesting a stable enzootic cycle. We found no evidence of insect domiciliation. Taken together, these observations suggest that eco-epidemiological factors shape the transmission dynamics of T. cruzi, creating diverse scenarios of disease transmission.

This opinion piece presents an approach to standardisation of an important aspect of Chagas disease drug discovery and development: selecting Trypanosoma cruzi strains for in vitro screening. We discuss the rationale for strain selection representing T. cruzi diversity and provide recommendations on the preferred parasite stage for drug discovery, T. cruzi discrete typing units to include in the panel of strains and the number of strains/clones for primary screens and lead compounds. We also consider experimental approaches for in vitro drug assays. The Figure illustrates the current Chagas disease drug-discovery and development landscape.

A single polymerase chain reaction (PCR) reaction targeting the spliced-leader intergenic region of Trypanosoma cruzi I was standardised by amplifying a 231 bp fragment in domestic (TcIDOM) strains or clones and 450 and 550 bp fragments in sylvatic strains or clones. This reaction was validated using 44 blind coded samples and 184 non-coded T. cruzi I clones isolated from sylvatic triatomines and the correspondence between the amplified fragments and their domestic or sylvatic origin was determined. Six of the nine strains isolated from acute cases suspected of oral infection had the sylvatic T. cruzi I profile. These results confirmed that the sylvatic T. cruzi I genotype is linked to cases of oral Chagas disease in Colombia. We therefore propose the use of this novel PCR reaction in strains or clones previously characterised as T. cruziI to distinguish TcIDOMfrom sylvatic genotypes in studies of transmission dynamics, including the verification of population selection within hosts or detection of the frequency of mixed infections by both T. cruzi I genotypes in Colombia.

Introducción. La enfermedad de Chagas, cuyo agente causal es Trypanosoma cruzi, constituye una antropozoonosis ampliamente distribuida en América Latina. Los estudios moleculares y los perfiles genéticos han demostrado que el parásito presenta una gran variabilidad y han permitido la clasificación de T. cruzi en seis unidades discretas de tipificación (I-VI), de las cuales, TcII a TcVI han sido ampliamente caracterizadas por distintos marcadores moleculares. Objetivo. Evaluar la variabilidad genética de TcI, mediante el uso de marcadores de microsatélites. Materiales y métodos. Se evaluaron siete microsatélites en quince aislamientos colombianos obtenidos mediante PCR a partir de reservorios, vectores y humanos, y se analizaron en un gel para desnaturalizar de poliacrilamida de un secuenciador láser fluorescente automático (ALF). Los datos se analizaron en un software para análisis de genética de poblaciones (Arlequin® 3.1 y Microsat®). Resultados. Los resultados demostraron variabilidad dentro de TcI al obtener 24 alelos, de los cuales, 12 se reportan por primera vez. Aunque se encontraron genotipos asociados a la infección humana y al ciclo selvático de transmisión, ningún locus permitió comprobar la presencia de los genotipos previamente reportados. Los parámetros de heterocigocidad observada y esperada, permitieron determinar la presencia de dos poblaciones (aislamientos domésticos y selváticos); asimismo, el desequilibrio de ligamento facilitó la creación de dos mapas físicos para los loci analizados. Conclusiones. Se corrobora la gran variabilidad genética presente en TcI, lo que sugiere un patrón de variación intraespecífica en Colombia.

Introduction: Chagas disease which is caused by the protozoan Trypanosoma cruzi, is a major public health problem in Latin American countries with a different distribution of the parasite across the continent in which nearly 15 million people are infected and 28 million are at risk. Genetic profiling of T. cruzi has shown great diversity and variability of the parasite allowing its classification into six discrete typing units (DTUs I-VI) in which TcII to TcVI are well characterized by different molecular markers. However, the presence of four subgroups according to the transmission cycle has only been reported in DTU T. cruzi I. Objective: To evaluate the genetic variability evidenced within TCI by the use of microsatellite markers. Materials and methods: Seven microsatellite loci were tested in fifteen Colombian isolates from vectors, reservoirs, and humans by means of PCR and automatic laser fluorescent sequencer (ALF). Data were analyzed using a population genetic data analysis software (Arlequin® 3.1 and Microsat®). Results: Variability among the isolates was demonstrated with 24 alleles, from which twelve had never been reported before. However, none of the microsatellite loci were able to support the idea of genotypes within TcI strains. The parameters of expected and observed heterozygocity allowed us to determine presence of two populations (domestic and sylvatic isolates); likewise, the linkage disequilibrium helped with the construction of two physical maps for the loci analyzed. Conclusions: We corroborated the high genetic variability displayed by TcI populations suggesting a pattern of intraspecific variation in Colombia.

The breeding sites of Culicoides pachymerus are described for the first time in western Boyacá Province, Colombia, where this species is a public health problem. In addition to being a nuisance due to its enormous density and its high biting rates, C. pachymerus cause dermatological problems in the human population. Analysis of microhabitats by the sugar flotation technique and the use of emergence traps allowed us to recover 155 larvae of Culicoides spp and 65 adults of C. pachymerus from peridomiciliary muddy substrates formed by springs of water and constant rainwater accumulation. These important findings could aid in the design of integrated control meas-ures against this pest.

Over the last 10 years, Uruguay, Chile and Brazil have been certified as being free from disease transmission by Triatoma infestans, the main domiciliated vector for Chagas disease in the Southern Cone countries. This demonstrates that programmes addressing the vector for the disease's transmission are effective. These programmes have resulted in a dramatic decrease in the incidence of Chagas disease in Latin America. Guatemala was certified a few months ago as being free from disease transmission by Rhodnius prolixus, the main domiciliated vector for Chagas disease in Central American countries. However, the main concern for different countries' current control programmes is the continuity and sustainability of future vector control actions. The prevalence and incidence figures for individuals infected by Trypanosoma cruzi in Mexico and Andean and Central American countries highlights the need for broadened strategies in the struggle against the disease and its vectors. A number of triatomine insects are parasite vectors, each with a different life history. Therefore, it is important that new vector control strategies be proposed, keeping in mind that some species are found in peridomiciliary areas and wild ecotopes. The only viable control strategy is to reduce human interactions with vector insects so that the re-infestation and re-colonisation of human habitats will not take place.

The bionomics of sand flies (Diptera: Phlebotominae) was studied monthly for two consecutive years in alluvial gallery forests in the department of Casanare, Northeastern Colombia. A total of 2,365 specimens and 10 species were captured using CDC light traps and Shannon traps, and from diurnal resting places, and human landing collections. Lutzomyia fairtigi Martins (55%), Lutzomyia micropyga (Mangabeira) (20.9%), and Lutzomyia antunesi (Coutinho) (13.5%) were the predominant species in the region. Lutzomyia flaviscutellata and Lutzomyia panamensis, potential vectors of Leishmania in Colombia and neighboring countries, were also collected, but in low numbers. Lu. fairtigi is an endemic species to Colombia, and minimal data are available on its biology and distribution. The present study provides additional information about Lu. fairtigi, such as the diurnal activity displayed by females on cloudy days, the greater density during the rainy season (April to October), marked anthropophilia, and the presence of flagellates in the midgut of one female.

The Andean Countries' Initiative (ACI) for controlling Chagas disease was officially created in 1997 within the framework of the Hipolito Unanue Agreement (UNANUE) between the Ministries of Health of Colombia, Ecuador, Peru, and Venezuela. Its objective was to interrupt transmission via vector and transfusion in the region, taking into account that there are 12.5 million people at risk in the four Andean countries forming the initiative in the area and around 3 million people are infected by Trypanosoma cruzi. The progress of control activities for the vector species present in the Andean sub-region, for different reasons, has been slow and control interventions have still not been installed in all geographical areas occupied by the target species. This has been partly due to lack of knowledge about these vector populations' biological characteristics, and consequent uncertainty about which are the appropriate control measures and strategies to be implemented in the region. The main vector species present important similarities in Venezuela and Colombia and in Ecuador and Northern Peru and they can be approached in a similar way throughout the whole regions, basing approaches on and adapting them to the current strategies being developed in Venezuela during the 1960s which have been progressively adopted in the Southern Cone and Central-American region. Additional measures are needed for keeping endemic areas free from Rhodnius prolixus silvatic populations, widely spread in the Orinoco region in Colombia and Venezuela. Regarding aetiological treatment, it is worth mentioning that (with the exception of Colombia) none of the other countries forming the ACI have registered medicaments available for treating infected young people. There are no suitable follow-up programmes in the sub-region or for treating cases of congenital Chagas disease. An integral and integrated programme encompassing all the aspects including transmission by transfusion which seems to have achieved extremely encouraging results in all countries, are urgently needed.

La información de 10 departamentos del total de 31 que contempla este manuscrito, ha sido publicada en "Memorias Primer Taller Internacional Sobre Control de la Enfermedad de Chagas. Curso de Diagnóstico, Manejo y Tratamiento de la Enfermedad de Chagas. VI Reunión de la Iniciativa Andina para el Control de la Enfermedad de Chagas, Bogotá; 2005. p.25-41. La presente publicación recopila la información de registros de triatominos y datos sobre infección natural con tripanosomátidos a nivel departamental y municipal, publicada hasta la fecha así como la reportada por los servicios departamentales de salud e institutos de investigación. Se presentan figuras elaboradas de acuerdo a la información suministrada por los registros y una clasificación de la fauna triatomínica de acuerdo a las condiciones ecoepidemiológicas del país, teniendo en cuenta la altitud como factor determinante en la distribución de estos insectos. Teniendo en cuenta la frecuencia con que se reportan en el domicilio y peridomicilio, se consideran las siguientes especies como las de mayor riesgo de transmisión en Colombia: Rhodnius prolixus, Triatoma dimidiata, Triatoma maculata y Triatoma venosa. Se resalta la importancia de la vigilancia entomológica como herramienta indispensable para reforzar las estrategias de control de la transmisión de la enfermedad de Chagas, permitiendo también la evaluación del riesgo que representan las especies de triatominos silvestres en Colombia.

Information concerning triatomine records from provinces and municipalities was accumulated-including data indicating natural infections with trypanosomatides-that has been previously published or reported by Colombian provincial health services and research institutes. Altitude appeared to be the main factor responsible for the distribution of the insects. Illustrations summarize the information provided by the above records. A triatomine fauna classification is presented that corresponds to the eco-epidemiological conditions of the country, considering altitude as the factor determining the geographical distribution of these vectors. Rhodnius prolixus, Triatoma dimidiata, Triatoma maculata and Triatoma venosa are considered the major transmission risk species in Colombia, according to the frequency in which they are reported inside dwellings and peridomiciliary areas. Entomological surveillance providess a necessary tool to reinforce the control strategies for Chagas disease. This also allows the evaluation of transmission risk that the sylvatic triatomines represent in Colombia.