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Made available in DSpace on 2022-04-28T19:46:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Agencia Nacional de Investigación e Innovación American University University of Arizona University of Vermont Junta de Andalucía Comisión Sectorial de Investigación Científica Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Ministerio de Educación y Cultura The subfamily Triatominae (Hemiptera-Reduviidae) includes more than 150 blood-sucking species, potential vectors of the protozoan Trypanosoma cruzi, causative agent of Chagas disease. A distinctive cytogenetic characteristic of this group is the presence of extremely stable chromosome numbers. Unexpectedly, the analyses of the chromosomal location of ribosomal gene clusters and other repetitive sequences place Triatominae as a significantly diverse hemipteran subfamily. Here, we advance the understanding of Triatominae chromosomal evolution through the analysis of the 45S rDNA cluster chromosomal location in 92 Triatominae species. We found the 45S rDNA clusters in one to four loci per haploid genome with different chromosomal patterns: On one or two autosomes, on one, two or three sex chromosomes, on the X chromosome plus one to three autosomes. The movement of 45S rDNA clusters is discussed in an evolutionary context. Our results illustrate that rDNA mobility has been relatively common in the past and in recent evolutionary history of the group. The high frequency of rDNA patterns involving autosomes and sex chromosomes among closely related species could affect genetic recombination and the viability of hybrid populations, which suggests that the mobility of rDNA clusters could be a driver of species diversification. Sección Genética Evolutiva Facultad de Ciencias Universidad de la República Department of Experimental Biology Genetics University of Jaén Department of Biomedicine and Biotechnology University of Alcalá Laboratório de Entomologia em Saúde Pública Departamento de Epidemiologia Faculdade de Saúde Pública Universidade de São Paulo Faculdade de Ciências Farmacêuticas Universidade Estadual Paulista “Júlio de Mesquita Filho” (Unesp) Fundação Oswaldo Cruz Laboratorio de Investigación en Genética Evolutiva – LIGE Universidad Pedagógica y Tecnológica de Colombia Programa de Biología Celular y Molecular ICBM Facultad de Medicina Universidad de Chile Laboratorio de Entomología Aplicada y Parasitología Escuela de Biología Facultad de Farmacia Universidad de San Carlos de Guatemala Department of Biological Sciences Loyola University New Orleans Departamento de Microbiología y Parasitología Facultad de Medicina Universidad Nacional Autónoma de México Faculdade de Ciências Farmacêuticas Universidade Estadual Paulista “Júlio de Mesquita Filho” (Unesp) Comisión Sectorial de Investigación Científica: 160 FAPESP: 17/05015-7 FAPESP: 19/02145-2 FAPESP: 307 398/2018-8 Ministerio de Educación y Cultura: II/FVF/2019/054

Despite successes in reducing transmission, Chagas disease (American trypanosomiasis) remains the greatest economic burden of any parasitic disease in Latin America afflicting mostly the poor and further contributing to poverty. We review a long-term (2001-2022), integrated Ecohealth approach that addresses sustainable development goals to reduce risk of Chagas transmission by the main native vector in Central America, Triatoma dimidiata, s.l. The basis of the Ecohealth intervention was the identification of the risk factors for house infestation, an understanding of and collaboration with local communities, and genetic and proteomic studies that revealed the epidemiology and mechanisms of the rapid reinfestation seen following insecticide application. We review the development of this approach from a pilot project in two Guatemalan villages, to an expanded initiative across three countries with vastly different ecology, cultures, and municipal organization, and finally development of a multi-institutional, large-scale project to develop a strategy to tackle the remaining hot spots in Central America. This integrated Ecohealth approach resulted in reduced risk of transmission as measured by a sustained decrease in house infestation without further use of insecticides, a reduction in vectors with human blood meals and the Chagas parasite, as well as other health and economic benefits. We discuss lessons learned and how this approach could be applied to other vector-borne diseases.

Chagas disease is a lethal, neglected tropical disease. Unfortunately, aggressive insecticide-spraying campaigns have not been able to eliminate domestic infestation of Triatoma dimidiata, the native vector in Guatemala. To target interventions toward houses most at risk of infestation, comprehensive socioeconomic and entomologic surveys were conducted in two towns in Jutiapa, Guatemala. Given the exhaustively large search space associated with combinations of risk factors, traditional statistics are limited in their ability to discover risk factor interactions. Two recently developed statistical evolutionary algorithms, specifically designed to accommodate risk factor interactions and heterogeneity, were applied to this large combinatorial search space and used in tandem to identify sets of risk factor combinations associated with infestation. The optimal model includes 10 risk factors in what is known as a third-order disjunctive normal form (i.e., infested households have chicken coops AND deteriorated bedroom walls OR an accumulation of objects AND dirt floors AND total number of occupants ≥ 5 AND years of electricity ≥ 5 OR poor hygienic condition ratings AND adobe walls AND deteriorated walls AND dogs). Houses with dirt floors and deteriorated walls have been reported previously as risk factors and align well with factors currently targeted by Ecohealth interventions to minimize infestation. However, the tandem evolutionary algorithms also identified two new socioeconomic risk factors (i.e., households having many occupants and years of electricity ≥ 5). Identifying key risk factors may help with the development of new Ecohealth interventions and/or reduce the survey time needed to identify houses most at risk.

Chagas disease is a parasitic infection that can insidiously cause non-ischemic cardiomyopathy. Given the largely silent nature of this progressive disease, asymptomatic blood donors pose potential blood transfusion risk. Blood donation screening has become an unintentional form of Chagas disease surveillance, with thousands of new cases identified since national surveillance was initiated in 2007.We recruited T. cruzi-positive blood donors identified from California and Arizona blood centers for confirmatory blood screening and assessment of lifetime infection risk.Among eight suspected cases, we identified four confirmed US autochthonous infections. The current manuscript details the transmission sources, healthcare-seeking behaviors post-blood donation resulting, and clinical course of disease among persons without any history of travel to endemic Latin American countries.This manuscript presents four additional US-acquired Chagas disease cases and identifies an opportunity for blood centers to assist in confronting barriers surrounding Chagas disease in the US.

Chagas disease is endemic to all seven Central American countries, where 12% of the population lives in areas where the disease is a risk. While neglect is a pervasive characteristic of Chagas disease in general, it tends to be especially overlooked in Central America, with more studies and resources devoted to the disease in South America. Here we report on the current epidemiological scenario of Chagas disease in Central America with the objective of presenting a panorama that includes national program details, recent morbidity data, new findings, and events relevant to the disease. Multinational initiatives and collaborations with external stakeholders that began around the beginning of this century led to the successful elimination of the vector species Rhodnius prolixus, which was last found in Guatemala in 2015. However, acute Chagas disease cases continue to be found in all countries with a surveillance system in place, mainly attributed to Trypanosoma cruzi transmission to humans by the native triatomine species Triatoma dimidiata and Rhodnius pallescens. Serological surveys targeting children have generally found varied T. cruzi infection prevalence, studies of transplacentally transmitted T. cruzi infection in the academic/public sectors have found a few cases in the region, and a new T. cruzi transmission focus was found in western Panama. Chagas disease transmission and prevalence have been reduced in Central America over the past two decades, but there is still much progress to be made toward interruption of T. cruzi transmission to humans by native vector species. Other key areas for improvement are implementing screening for T. cruzi infection in pregnant women, improving reliability of diagnostic tests, expanding access to etiological treatment, and increasing availability and quality of data.

In Central America, most new human Trypanosoma cruzi infections (Chagas disease) are vector-borne, primarily by native vector species. Given the importance of vector control in reducing Chagas disease incidence, here, we provide an updated report on the recent advances and the latest research in vector ecology and control in Central America. Our objective is to present a panorama of the current situation that includes vector control program details, recent public health activities and academic research, and current challenges faced by each country and the region as a whole. With the elimination of the introduced species Rhodnius prolixus from the region, the primary vector control challenge is control of native species that move between sylvan and domestic environments, namely Triatoma dimidiata and Rhodnius pallescens. These species cannot be eliminated from domestic/peridomestic settings in a sustainable way using insecticide alone, as residual members of domestic populations and/or sylvatic foci allow the species to persistently reinfest following insecticide application. Implementation of integrated, multidisciplinary methods for native vector species control has yielded promising results. In particular, projects using the Ecohealth method have been scaled up and expanded to endemic areas in multiple countries through partnerships between international stakeholders and ministries of health (MoHs). Additionally, the recent description of two new triatomine bug species that were once classified as T. dimidiata may help to tailor vector control methods to interspecies variations, and the discovery of a dark morph of R. pallescens may provide further insight into vector control in Panama. Finally, associations between deforestation and vector T. cruzi infection and abundance in Panama call attention to associations between human land use change and Chagas disease risk. The elimination of R. prolixus contributed to significant reductions in human T. cruzi infection incidence in Central America over the past 20 years, but native vector species still pose a significant public health threat. New methods and collaborations present promising solutions, but sustained partnerships, long-term commitment, and strong regional leadership are required to see them through.

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, peri‑domestic 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.

Scientific collections such as the U.S. National Museum (USNM) are critical to filling knowledge gaps in molecular systematics studies. The global taxonomic impediment has resulted in a reduction of expert taxonomists generating new collections of rare or understudied taxa and these large historic collections may be the only reliable source of material for some taxa. Integrated systematics studies using both morphological examinations and DNA sequencing are often required for resolving many taxonomic issues but as DNA methods often require partial or complete destruction of a sample, there are many factors to consider before implementing destructive sampling of specimens within scientific collections. We present a methodology for the use of archive specimens that includes two crucial phases: 1) thoroughly documenting specimens destined for destructive sampling—a process called electronic vouchering, and 2) the pipeline used for whole genome sequencing of archived specimens, from extraction of genomic DNA to assembly of putative genomes with basic annotation. The process is presented for eleven specimens from two different insect subfamilies of medical importance to humans: Anophelinae (Diptera: Culicidae)—mosquitoes and Triatominae (Hemiptera: Reduviidae)—kissing bugs. Assembly of whole mitochondrial genome sequences of all 11 specimens along with the results of an ortholog search and BLAST against the NCBI nucleotide database are also presented.

Kissing bugs, Triatoma recurva (Stal) (Hemiptera: Reduviidae: Triatominae), live in an environment with high seasonal variability in rainfall, humidity, temperature, and food sources, and are an ideal organism for testing adaptive plasticity in rate of maturation to adult and in reproduction. Under simulated natural conditions, the effect of abundant, moderate, and infrequent feeding opportunities upon developmental rate, growth, and fecundity of the bugs was determined. Insects afforded frequent feeding opportunities matured to adult faster than those on lower frequency feeding diets. Insects on limited frequency feeding diets often delayed maturation until the second year of life and gained weight relative to those that matured in the first year. The females fed the least frequently and that delayed maturation until the second year doubled in weight relative to those maturing the year-earlier. In this species living near the climatic extremes of members of its genus, developmental and reproductive plasticity appear to be viable options to minimize the effects of catastrophes and reduce the possibility of local extinction during extreme environmental conditions.

Assays for parasite detection in insect vectors provide important information for disease control. American Trypanosomiasis (Chagas disease) is the most devastating vector-borne illness and the fourth most common in Central America behind HIV/AIDS and acute respiratory and diarrheal infections (Peterson et al., 2019). Under-detection of parasites is a general problem which may be influenced by parasite genetic variation; however, little is known about the genetic variation of the Chagas parasite, especially in this region. In this study we compared six assays for detecting the Chagas parasite, Trypanosoma cruzi: genomic reduced representation sequencing (here referred to as genotype-by-sequencing or GBS), two with conventional PCR (i.e., agarose gel detection), two with qPCR, and microscopy. Our results show that, compared to GBS genomic analysis, microscopy and PCR under-detected T. cruzi in vectors from Central America. Of 94 samples, 44% (50/94) were positive based on genomic analysis. The lowest detection, 9% (3/32) was in a subset assayed with microscopy. Four PCR assays, two with conventional PCR and two with qPCR showed intermediate levels of detection. Both qPCR tests and one conventional PCR test targeted the 195 bp repeat of satellite DNA while the fourth test targeted the 18S gene. Statistical analyses of the genomic and PCR results indicate that the PCR assays significantly under detect infections of Central American T. cruzi genotypes.

To date, the phylogeny of Triatoma dimidiata sensu lato (s. l.) (Hemiptera: Reduviidae: Triatominae), the epidemiologically most important Chagas disease vector in Central America and a secondary vector in Mexico and northern South America, has only been investigated by one multi-copy nuclear gene (Internal Transcribed Spacer – 2) and a few mitochondrial genes. We examined 450 specimens sampled across most of its native range from Mexico to Ecuador using reduced representation next-generation sequencing encompassing over 16,000 single nucleotide polymorphisms (SNPs). Using a combined phylogenetic and species delimitation approach we uncovered two distinct species, as well as a well-defined third group that may contain multiple species. The findings are discussed with respect to possible drivers of diversification and the epidemiological importance of the distinct species and groups.

Posttraumatic stress disorder (PTSD) is a leading cause of impairments in quality of life and functioning among Veterans. Service dogs have been promoted as an effective adjunctive intervention for PTSD, however published research is limited and design and implementation flaws in published studies limit validated conclusions. This paper describes the rationale for the study design, a detailed methodological description, and implementation challenges of a multisite randomized clinical trial examining the impact of service dogs on the on the functioning and quality of life of Veterans with PTSD. Trial design considerations prioritized participant and intervention (dog) safety, selection of an intervention comparison group that would optimize enrollment in all treatment arms, pragmatic methods to ensure healthy well-trained dogs, and the selection of outcomes for achieving scientific and clinical validity in a Veteran PTSD population. Since there is no blueprint for conducting a randomized clinical trial examining the impact of dogs on PTSD of this size and scope, it is our primary intent that the successful completion of this trial will set a benchmark for future trial design and scientific rigor, as well as guiding researchers aiming to better understand the role that dogs can have in the management of Veterans experiencing mental health conditions such as PTSD.

BACKGROUND DNA- and proteomics-based techniques are currently used to identify a triatomine human blood meal. These methods are time consuming, require access to laboratories with sophisticated equipment, and trained personnel. OBJECTIVES We tested a rapid and specific immunochromatographic assay (that detects human blood in forensic samples) to determine if human blood was present in triatomines and their fecal excreta. METHODS We fed Triatoma rubida human blood (positive control) or mouse blood (negative control) and performed the assay on the abdominal contents and fecal excreta. Triatomine field specimens collected in and around human habitations and excreta were also tested. FINDINGS The assay was positive in triatomines fed human blood (N = 5/5) and fecal excreta from bugs known to have ingested human blood (N = 5/5). Bugs feeding on mice (N = 15/15) and their fecal excreta (N = 8/8) were negative for human blood. Human blood was detected in 47% (N = 23/49) triatomines, representing six different species, collected in the field. MAIN CONCLUSIONS The pilot study shows that this rapid and specific test may have applications in triatomine research. Further study is needed to determine the sensitivity of this assay compared to other well-established techniques, such as DNA- and proteomics-based methodologies and the assay’s application in the field.

Background Kissing bugs are common household pests in the Desert Southwest of the United States. These hematophagous bugs enter homes and suck blood from resident humans and pets. They are vectors of Trypanosoma cruzi, an enzootic parasite in small mammals and the cause of Chagas disease in humans. Autochthonous cases of Chagas disease are rare in the United States despite the presence of the vector and parasite. Environmental and biological factors accounting for this phenomenon need studying. Methods Homeowners in Bisbee and Tucson, Arizona captured kissing bugs inside homes during 2017-2018. Bugs were tested for presence of T. cruzi by polymerase chain reaction. Residents bitten by kissing bugs were tested for Chagas disease by serology. We evaluated invaded homes in the 2 cities. Results Three species of kissing bugs (n = 521) were collected in or near homes. Triatoma rubida was the most common triatomine in Tucson; T. recurva in Bisbee. T. protracta was uncommon. Seventeen percent of bugs captured in Bisbee and 51.1% in Tucson harbored T. cruzi. Bite victims (n = 105) recalled more than 2200 bites. Reactions to bites were common, including 32 episodes of anaphylaxis in 11 people (10.5%). Tests for Chagas disease (n = 116) were negative. Median age of houses was 91 years in Bisbee and 7 years in Tucson. Bisbee houses had pier and beam foundations. Tucson houses were built on concrete slabs. Conclusions Kissing bugs harboring T. cruzi readily entered new and old homes. Bites of humans caused severe, life-threatening reactions. There was no serological evidence of Chagas disease among those bitten.

The widespread and diverse Triatoma dimidiata is the kissing bug species most important for Chagas disease transmission in Central America and a secondary vector in Mexico and northern South America. Its diversity may contribute to different Chagas disease prevalence in different localities and has led to conflicting systematic hypotheses describing various populations as subspecies or cryptic species. To resolve these conflicting hypotheses, we sequenced a nuclear (internal transcribed spacer 2, ITS-2) and mitochondrial gene (cytochrome b) from an extensive sampling of T. dimidiata across its geographic range. We evaluated the congruence of ITS-2 and cyt b phylogenies and tested the support for the previously proposed subspecies (inferred from ITS-2) by: (1) overlaying the ITS-2 subspecies assignments on a cyt b tree and, (2) assessing the statistical support for a cyt b topology constrained by the subspecies hypothesis. Unconstrained phylogenies inferred from ITS-2 and cyt b are congruent and reveal three clades including two putative cryptic species in addition to T. dimidiata sensu stricto. Neither the cyt b phylogeny nor hypothesis testing support the proposed subspecies inferred from ITS-2. Additionally, the two cryptic species are supported by phylogenies inferred from mitochondrially-encoded genes cytochrome c oxidase I and NADH dehydrogenase 4. In summary, our results reveal two cryptic species. Phylogenetic relationships indicate T. dimidiata sensu stricto is not subdivided into monophyletic clades consistent with subspecies. Based on increased support by hypothesis testing, we propose an updated systematic hypothesis for T. dimidiata based on extensive taxon sampling and analysis of both mitochondrial and nuclear genes.

Kissing bugs in the genus Triatoma are obligate blood feeders that feed mainly on vertebrate blood and have lost the predatory lifestyle found in other reduviid bugs. They occasionally also feed on the hemolymph of arthropods, especially during the first and second instar stages. The largest kissing bug species in the United States, Triatoma recurva (Stal) (Hemiptera: Reduviidae), is poorly known and was chosen to investigate its ability to feed and develop on a diet of cockroach hemolymph. Molting from first instar individuals to second instars readily occurred at approximately the same rate reported for the species feeding on mammalian blood. Subsequent instars also fed on and survived on cockroach hemolymph with some individuals maturing to adults. In the larger instars, development time and survival rates were reduced relative to the results reported in the literature for mammalian-blood-fed individuals. Two other species of kissing bugs, Triatoma protracta (Uhler) and T. rubida (Uhler) failed to survive on cockroach hemolymph with most individuals failing to molt from the first instar stage. Although T. recurva does not thrive on a diet limited to hemolymph of cockroaches, it appears to be an unusual species in which cockroaches might be a primary source of nutrition for smaller individuals and are a viable exclusive source of nutrition for all immatures. At a minimum during times of limited availability of vertebrate blood sources, the presence of cockroaches enhances survival opportunities. Efforts to control populations of this kissing bug species likely will be improved with additional control of cockroach populations in the environment.

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and transmitted by triatomine insect vectors. In Guatemala, insecticide spraying is an integral part of management of the main vector, Triatoma dimidiata. Spraying typically has low efficacy, which may be due to incomplete elimination from infested houses, within-village dispersal, or influx from other villages or sylvan environments. To evaluate how these mechanisms contribute to reinfestation, we conducted a time-course analysis of T. dimidiata infestation, abundance and household genetic structure in two nearby villages in Jutiapa, Guatemala; houses in the first village were surveyed, treated with insecticide if infested and then re-surveyed at eight and 22 months following spraying, while the second village served as an untreated control to quantify changes associated with seasonal dispersal. Insects were genotyped at 2–3000 SNP loci for kinship and population genetic analyses. Insecticide application reduced overall infestation and abundance, while the untreated village was stable over time. Nevertheless, within two years 35.5% of treated houses were reinfested and genetic diversity had largely recovered. Insects collected from reinfested houses post-spraying were most closely related to pre-spray collections from the same house, suggesting that infestations had not been fully eliminated. Immigration by unrelated insects was also detected within a year of spraying; when it occurred, dispersal was primarily local from neighboring houses. Similar dispersal patterns were observed following the annual dispersal season in the untreated village, with high-infestation houses serving as sources for neighboring homes. Our findings suggest that the efficacy of pyrethroid application is rapidly diminished by both within-house breeding by survivors and annual cycles of among-house movement. Given these patterns, we conclude that house structural improvements, an integral part of the Ecohealth approach that makes houses refractory to vector colonization and persistence, are critical for long-term reduction of T. dimidiata infestation.

A new species of the genus Triatoma Laporte, 1832 (Hemiptera, Reduviidae) is described based on specimens collected in the department of Huehuetenango, Guatemala. Triatomahuehuetenanguensissp. 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.

Chagas disease, considered a neglected disease by the World Health Organization, is caused by the protozoan parasite Trypanosoma cruzi, and transmitted by >140 triatomine species across the Americas. In Central America, the main vector is Triatoma dimidiata, an opportunistic blood meal feeder inhabiting both domestic and sylvatic ecotopes. Given the diversity of interacting biological agents involved in the epidemiology of Chagas disease, having simultaneous information on the dynamics of the parasite, vector, the gut microbiome of the vector, and the blood meal source would facilitate identifying key biotic factors associated with the risk of T. cruzi transmission. In this study, we developed a RADseq-based analysis pipeline to study mixed-species DNA extracted from T. dimidiata abdomens. To evaluate the efficacy of the method across spatial scales, we used a nested spatial sampling design that spanned from individual villages within Guatemala to major biogeographic regions of Central America. Information from each biotic source was distinguished with bioinformatics tools and used to evaluate the prevalence of T. cruzi infection and predominant Discrete Typing Units (DTUs) in the region, the population genetic structure of T. dimidiata, gut microbial diversity, and the blood meal history. An average of 3.25 million reads per specimen were obtained, with approximately 1% assigned to the parasite, 20% to the vector, 11% to bacteria, and 4% to putative blood meals. Using a total of 6,405 T. cruzi SNPs, we detected nine infected vectors harboring two distinct DTUs: TcI and a second unidentified strain, possibly TcIV. Vector specimens were sufficiently variable for population genomic analyses, with a total of 25,710 T. dimidiata SNPs across all samples that were sufficient to detect geographic genetic structure at both local and regional scales. We observed a diverse microbiotic community, with significantly higher bacterial species richness in infected T. dimidiata abdomens than those that were not infected. Unifrac analysis suggests a common assemblage of bacteria associated with infection, which co-occurs with the typical gut microbial community derived from the local environment. We identified vertebrate blood meals from five T. dimidiata abdomens, including chicken, dog, duck and human; however, additional detection methods would be necessary to confidently identify blood meal sources from most specimens. Overall, our study shows this method is effective for simultaneously generating genetic data on vectors and their associated parasites, along with ecological information on feeding patterns and microbial interactions that may be followed up with complementary approaches such as PCR-based parasite detection, 18S eukaryotic and 16S bacterial barcoding., Author summary Chagas disease is caused by the parasite Trypanosoma cruzi, which is spread by triatomine kissing bugs. There are many biotic factors that influence the risk of disease transmission, including the strain of the parasite, the vector movement patterns, the community of microbes interacting with the parasite inside the vector's gut, and the availability of suitable vertebrate hosts. DNA from all of these species can be found in the gut of an infected bug, providing an opportunity to investigate all of them simultaneously by genetically analyzing this single tissue. In this study, we developed a DNA-based method to retrieve, separate, and analyze genetic information from the abdomens of 32 T. dimidiata kissing bug vectors collected across Central America. We found two distinct strains of T. cruzi, and four T. dimidiata genetic clusters associated with environmental and geographical characteristics. These populations harbored different bacterial gut communities that were augmented by specifically infection-associated bacteria when the vector was infected by the parasite. In some cases, we could identify what the insect had recently fed on, including chicken, duck, dog and human. Having simultaneous information on all of these organisms may help to fine-tune control strategies that influence the risk of T. cruzi transmission.

Triatoma dimidiata (Latreille, 1811) is the most abundant and significant insect vector of the parasite Trypanosoma cruzi in Central America, and particularly in Guatemala. Tr. cruzi is the causative agent of Chagas disease, and successful disease control requires understanding the geographic distribution and degree of migration of vectors such as T. dimidiata that frequently re-infest houses within months following insecticide application. The population genetic structure of T. dimidiata collected from six villages in southern Guatemala was studied to gain insight into the migration patterns of the insects in this region where populations are largely domestic. This study provided insight into the likelihood of eliminating T. dimidiata by pesticide application as has been observed in some areas for other domestic triatomines such as Triatoma infestans. Genotypes of microsatellite loci for 178 insects from six villages were found to represent five genetic clusters using a Bayesian Markov Chain Monte Carlo method. Individual clusters were found in multiple villages, with multiple clusters in the same house. Although migration occurred, there was statistically significant genetic differentiation among villages (FR T = 0.05) and high genetic differentiation among houses within villages (FSR = 0.11). Relatedness of insects within houses varied from 0 to 0.25, i.e., from unrelated to half-sibs. The results suggest that T. dimidiata in southern Guatemala moves between houses and villages often enough that recolonization is likely, implying the use of insecticides alone is not sufficient for effective control of Chagas disease in this region and more sustainable solutions are required.

In this paper, Triatoma mopan sp. n. is described based on five males and six females collected in the Rio Frio cave, Cayo District, Belize. This species is similar to Triatoma dimidiata (Latreille), but can be distinguished by characters found on the pronotum, legs, and abdomen. Geometric morphometry and phylogenetic comparisons are also provided. Presently, the species is known only from the type locality and is a potential Chagas vector.

Phylogenetic relationships of insect vectors of parasitic diseases are important for understanding the evolution of epidemiologically relevant traits, and may be useful in vector control. The sub-family Triatominae (Hemiptera:Reduviidae) includes ∼140 extant species arranged in five tribes comprised of 15 genera. The genus Triatoma is the most species-rich and contains important vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Triatoma species were grouped into complexes originally by morphology and more recently with the addition of information from molecular phylogenetics (the four-complex hypothesis); however, without a strict adherence to monophyly. To date, the validity of proposed species complexes has not been tested by statistical tests of topology. The goal of this study was to clarify the systematics of 19 Triatoma species from North and Central America. We inferred their evolutionary relatedness using two independent data sets: the complete nuclear internal transcribed spacer-2 ribosomal DNA (ITS-2 rDNA) and head morphometrics. In addition, we used the Shimodaira-Hasegawa statistical test of topology to assess the fit of the data to a set of competing systematic hypotheses (topologies). An unconstrained topology inferred from the ITS-2 data was compared to topologies constrained based on the four-complex hypothesis or one inferred from our morphometry results. The unconstrained topology represents a statistically significant better fit of the molecular data than either the four-complex or the morphometric topology. We propose an update to the composition of species complexes in the North and Central American Triatoma, based on a phylogeny inferred from ITS-2 as a first step towards updating the phylogeny of the complexes based on monophyly and statistical tests of topologies.

Background Kissing bugs, vectors of Trypanosoma cruzi , the parasite that causes Chagas disease, are common in the desert Southwest. After a dispersal flight in summer, adult kissing bugs occasionally gain access to houses where they remain feeding on humans and pets. How often wild, free-roaming kissing bugs feed on humans outside their homes has not been studied. This is important because contact of kissing bugs with humans is one means of gauging the risk for acquisition of Chagas disease. Methods We captured kissing bugs in a zoological park near Tucson, Arizona, where many potential vertebrate hosts are on display, as well as being visited by more than 300,000 humans annually. Cloacal contents of the bugs were investigated for sources of blood meals and infection with T. cruzi . Results Eight of 134 captured bugs were randomly selected and investigated. All 8 (100%) had human blood in their cloacae, and 7 of 8 (88%) had fed on various vertebrates on display or feral in the park. Three bugs (38%) were infected with T. cruzi . Three specimens of the largest species of kissing bug in the United States ( Triatoma recurva ) were captured in a cave and walking on a road; 2 of 3 (67%) had fed on humans. No T. recurva harbored T. cruzi . Conclusions This study establishes that free-roaming kissing bugs, given the opportunity, frequently feed on humans outside the confines of their homes in the desert Southwest and that some harbored T. cruzi . This could represent a hitherto unrecognized potential for transmission of Chagas disease in the United States.

Triatoma dimidiata, a Chagas disease vector distributed in Mexico, Central America, Colombia, Venezuela, Peru and Ecuador, has been studied using genetic markers and four groups have been defined by ITS–2 sequences: 1A, 1B, 2 and 3. To gather evidence on the divergence and reproductive isolation among T. dimidiata ITS–2 groups, we carried out 15 crossbreeding experiments with field–collected sylvan and domestic T. dimidiata from Guatemala where three groups are found: 1A, 2 and 3. Reciprocal crosses between individuals from groups 1A and 2, and a cross between group 2 individuals from different habitats, produced an average 129.78±42.29 eggs with hatching success ranging from 31.6% to 90.1%. The offspring of these crosses reached the adult stage, and crosses between F1 insects produced eggs. These results suggest that there are no pre– or post– zygotic reproductive barriers between groups 1A and 2, or within group 2. Crosses between group 3 females and males from groups 1A or 2 produced on average 85.67±30.26 eggs and none of them hatched. These results support the existence of pre– zygotic barriers between T. dimidiata group 3 and groups 1A and 2. The group 3 individuals were collected in sylvatic environments in Yaxha, Peten, Guatemala. Previously, distinct chromosomal characteristics (cytotype 3) were described in individuals from this population. Based on this evidence we suggest that this population is divergent at the species level from other T. dimidiata populations.

A high proportion of triatomine insects, vectors for Trypanosoma cruzi trypanosomes, collected in Arizona and California and examined using a novel assay had fed on humans. Other triatomine insects were positive for T. cruzi parasite infection, which indicates that the potential exists for vector transmission of Chagas disease in the United States.

From May through November 2007, intensive weekly surveys at the site of a previously reported autochthonous human case of Chagas parasite infection resulted in the collection of 298 Triatoma sanguisuga (Leconte) specimens, of which 60.4% (180) were polymerase chain reaction positive for Trypanosoma cruzi Chagas. All were adults, in a ratio of approximately 1:1 female to male, indicating that the domicile was not colonized, but was a destination for these host-seeking adults. We report on seasonal activity pattern, T. cruzi prevalence in T. sanguisuga, and attempts at insect exclusion and control at the case residence.

Triatoma dimidiata is one of the major Chagas disease vectors, with an extensive diversity in its morphology, habitat, and level of domiciliation. Molecular studies based on the internal transcribed spacer 2 (ITS-2) have subdivided this species into four potential taxonomic groups. Using both ITS-2 and cytochrome B markers, we confirmed the sibling species status of ITS-2 Group 3 and detected an apparent sympatry of ITS-2 Groups 2 and 3 in the Yucatan peninsula, Mexico. Here we examine the geographic distribution of T. dimidiata ITS-2 genotypes in the region and compare their egg production and Trypanosoma cruzi infection rates, as indicators of biological differences between groups. PCR genotyping of large natural populations showed an extensive sympatry of Groups 2 and 3 in most of the peninsula, often within the same house. We also detected a large proportion of individuals displaying ITS-2 sequences from both Groups 2 and 3, suggesting hybridization. Analysis of ITS-2 genotype frequencies indicated a strong departure from Hardy–Weinberg equilibrium in female hybrids, but not in males, due to a large heterozygote deficit. These results suggest random mating between ITS-2 Groups 2 and 3 combined with reduced viability and/or survival in female hybrids. This and other factors may allow for the maintenance of distinct ITS-2 Groups 2 and 3 populations despite high hybrid frequencies. Importantly, T. cruzi infection was much higher in hybrids compared to ITS-2 Groups 2 and 3 individuals, but all three genotypes appeared to seasonally infest houses in a similar manner in the region. These findings warrant further studies on T. dimidiata taxonomy and its epidemiologic implications.

Chagas disease is an emerging infectious disease in North America due to the immigration of individuals from endemic areas. The parasite has been transmitted to patients in non-endemic areas by blood transfusion and organ donation. Only six autochthonous cases have been described in humans in the United States yet the parasite is widespread among native mammals and resident triatomines are competent vectors. We attempted to determine if common southwestern triatomines, Triatoma protracta and Triatoma rubida have the potential to amplify the disease among human residents of the Southwest. The defecation patterns of the bugs were studied while feeding upon immobilized mice. Wild-caught adult male and female triatomines were observed feeding one to three times for a total of 71 observed feedings. T. rubida (15 bugs) appeared to be more aggressive, beginning feeding shortly after being placed in proximity to the host (within 2.3 min) whereas Triatoma protracta (12 bugs) was more deliberate, beginning feeding, on average, at 4 min. There were 40 observations of T. rubida, which fed for 27.9+/-13.6 min, whereas T. protracta fed for 22.8+/-7.5 min (n=31). Bugs were weighed pre- and post-feeding and T. rubida females ingested>T. protracta females>T. rubida males>T. protracta males. Weight gain did not correspond to the feeding duration. Defecation occurred on 42% of the feedings (30 of 71), and no bugs defecated on the host. The majority of the defecations occurred within 1 min of feeding, usually at the time of repletion. A large proportion of defecations occurred after the bugs left the vicinity of the host. All bugs and at least one fecal smear from each feeding bug were tested for Trypanosoma cruzi and 21% of T. protracta were positive by PCR (4 bugs and 1 feces). No T. rubida tested positive for T. cruzi. The bugs' defecation pattern is similar to that reported >50 years ago. Furthermore, there is no indication that they are becoming more domesticated in the desert Southwest. Thus, based on our observations, we do not believe that T. protracta and T. rubida pose an imminent risk for transmission of Chagas disease to residents of the southwestern United States.

This article describes a web-based data entry and GIS-driven mapping system designed for an ethnographic and entomological survey of Chagas' disease, an emerging zoonotic disease, and Triatoma dimidiata , a primary vector, in the Los Tuxtlas region of Veracruz, Mexico. To better understand this disease in the region, a collaborative, multi-disciplinary study was initiated to conduct a spatial investigation of T. dimidiata and a community-by-community survey of local perceptions of the disease. In order to facilitate such a collaborative effort the CODES-GIS was developed. This system allows for (near) real-time mapping, analyses, disease reporting, and results sharing. CODES-GIS provides a framework for a research team working in a remote area with limited technology, software, or GIS expertise to benefit from (near) real-time spatial analyses performed at collaborating institutions. The system is bi-directional, where field personnel can upload data to the system for field-based map production. Likewise, laboratory personnel can upload diagnostics data for viewing by field personnel. In this way, the system provides a virtual link between the field and the laboratory to increase

Seven Triatoma dimidiata (Latreille, 1811) populations from different provinces of Guatemala were compared along with three related triatomine species using the electrophoretic profiles of salivary proteins. The analysis of salivary proteins allowed the separation of two of the species into their respective complexes, phyllosoma (T. pallidipennis) and protracta (T. nitida) (Lent and Wygodzinsky, 1979), whereas T. dimidiata seems slightly separated from either of these. Based on salivary protein profiles, T. dimidiata is most closely related to the cluster including T. ryckmani and T. nitida (protracta) and more diverged from T. pallidipennis (phyllosoma). Among Guatemalan T. dimidiata populations, the cave population from Lanquin is separated from the rest of populations analyzed, suggesting that it is in the process of speciation. No difference in protein banding pattern was observed among populations from domestic and peridomestic ecotopes from the same region.

The population genetics of Triatoma dimidiata (Latreille, 1811) from five different provinces in Guatemala, including three sylvan and three domestic populations, was investigated by random amplification of polymorphic DNA-polymerase chain reaction. There is a high degree of genetic variation in all of the T. dimidiata populations as evidenced by high levels of average expected heterozygosity and polymorphism. Domestic populations are more closely related to each other (D = 0.05-0.085, Nei's genetic distance) than are the sylvan (D = 0.121-0.189). Within the limited sample size of three populations, there was a correlation with geographic and genetic distance for the domestic populations, but not for the sylvan. Surprisingly, one of the sylvan populations was genetically very similar to the domestic populations. The FST demonstrated a high degree of differentiation at the country-wide level (FST = 0.175) and a moderate degree of differentiation within the sylvan (FST = 0.135) or domestic (FST = 0.097) populations. Although these results demonstrated that gene flow is limited between different provinces in Guatemala, hierarchical analysis showed that barriers between the Atlantic and Pacific drainage slopes were not biologically significant limiters of gene flow.