Spatial distribution of acute cases of Chagas disease reported from 2010 to 2020 in the State of Amazonas / Distribuição espacial dos casos agudos de doença de Chagas notificados de 2010 a 2020 no Estado da Amazônia / Distribución espacial de los casos agudos de enfermedad de Chagas notificados de 2010 a 2020 en el Estado Amazónico

This study aimed to investigate the epidemiology of acute cases of Chagas disease notified in the State of Amazonas between the period from 2010 to 2020. Data were obtained from the portal of the Sistema de Informação de Agravos de Notificação- SINAN, considering the number of cases per municipality of notification. 140 cases of Acute Chagas Disease were notified, distributed in 23 of the 62 municipalities of the State of Amazonas, 82 (59%) were male individuals, with a greater predominance in the age group of 20-39 years old, having 45 (32.1%) cases. As for the race/color variable, the highest number was among brown people with 101 (72.1%) notifications. The oral route prevailed as the main form of disease transmission with 93 (66.4%) records. Infection by the oral route of T. cruzi is the most important route of transmission of CD in the State of Amazonas, the occurrence of transmission is associated in most cases with the consumption of foods such as açaí juice and has been reported frequently over the years between municipalities.

este estudo se propôs a investigar a epidemiologia dos casos agudos de Doença de Chagas notificados no Estado do Amazonas no período de 2010 a 2020. Os dados foram obtidos no portal do Sistema de Informação de Agravos de Notificação - SINAN, considerando o número de casos por município de notificação. Foram notificados 140 casos de Doença de Chagas Aguda, distribuídos em 23 dos 62 municípios do Estado do Amazonas, 82 (59%) eram indivíduos do sexo masculino, com maior predominância na faixa etária de 20-39 anos de idade com 45 (32,1%) casos. Quanto a variável raça/cor, a maior registro foi entre pardos com 101(72,1%) notificações. A via oral, prevaleceu como a principal forma de transmissão da patologia com 93 (66,4%) registros. A infecção pela via oral do T. cruzi, é a mais importante via de transmissão de DC no Estado do Amazonas, a ocorrência da transmissão está associada na maioria das vezes ao consumo de alimentos como o suco de açaí, e tem sido reportada com frequência ao longo dos anos entre os municípios.

Este estudio tuvo como objetivo investigar la epidemiología de los casos agudos de la enfermedad de Chagas notificados en el Estado de Amazonas en el período de 2010 a 2020. Los datos fueron obtenidos del portal del Sistema de Información de Enfermedades de Notificación - SINAN, considerando el número de casos por municipio de notificación. Se notificaron 140 casos de Enfermedad de Chagas Aguda, distribuidos en 23 de los 62 municipios del Estado de Amazonas, 82 (59%) fueron individuos del sexo masculino, con mayor predominio en el grupo etario de 20 a 39 años con 45 (32,1%) casos. En cuanto a la variable raza/color, el mayor número fue entre los morenos con 101 (72,1%) notificaciones. La vía oral predominó como principal vía de transmisión de la enfermedad con 93 (66,4%) registros. La infección por vía oral de T. cruzi es la vía de transmisión más importante de la EC en el Estado de Amazonas, la ocurrencia de la transmisión está mayoritariamente asociada al consumo de alimentos como el jugo de açaí, y ha sido reportada con frecuencia a lo largo de los años entre municipios.

Dynamics of Triatoma infestans populations in the Paraguayan Chaco: Population genetic analysis of household reinfestation following vector control.

BACKGROUND: Although domestic infestations by Triatoma infestans have been successfully controlled across Latin America, in areas of the Gran Chaco region, recurrent post-spraying house colonization continues to be a significant challenge, jeopardizing Chagas disease vector control and maintaining active Trypanosoma cruzi transmission. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the dynamics of triatomine reinfestation in a rural area of the Paraguayan Chaco, genetic characterization (based on 10 microsatellite loci and cytochrome B sequence polymorphisms) was performed on baseline and reinfestant T. infestans (n = 138) from four indigenous communities and adjacent sylvatic sites. House quality and basic economic activities were assessed across the four communities. Significant genetic differentiation was detected among all baseline triatomine populations. Faster reinfestation was observed in the communities with higher infestation rates pre-spraying. Baseline and reinfestant populations from the same communities were not genetically different, but two potentially distinct processes of reinfestation were evident. In Campo Largo, the reinfestant population was likely founded by domestic survivor foci, with reduced genetic diversity relative to the baseline population. However, in 12 de Junio, reinfestant bugs were likely derived from different sources, including survivors from the pre-spraying population and sympatric sylvatic bugs, indicative of gene-flow between these habitats, likely driven by high human mobility and economic activities in adjacent sylvatic areas. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that sylvatic T. infestans threatens vector control strategies, either as a reinfestation source or by providing a temporary refuge during insecticide spraying. Passive anthropogenic importation of T. infestans and active human interactions with neighboring forested areas also played a role in recolonization. Optimization of spraying, integrated community development and close monitoring of sylvatic areas should be considered when implementing vector control activities in the Gran Chaco.

Assessing risk of vector transmission of Chagas disease through blood source analysis using LC-MS/MS for hemoglobin sequence identification.

Chagas disease is mainly transmitted by triatomine insect vectors that feed on vertebrate blood. The disease has complex domiciliary infestation patterns and parasite transmission dynamics, influenced by biological, ecological, and socioeconomic factors. In this context, feeding patterns have been used to understand vector movement and transmission risk. Recently, a new technique using Liquid chromatography tandem mass spectrometry (LC-MS/MS) targeting hemoglobin peptides has showed excellent results for understanding triatomines' feeding patterns. The aim of this study was to further develop the automated computational analysis pipeline for peptide sequence taxonomic identification, enhancing the ability to analyze large datasets data. We then used the enhanced pipeline to evaluate the feeding patterns of Triatoma dimidiata, along with domiciliary infestation risk variables, such as unkempt piles of firewood or construction material, cracks in bajareque and adobe walls and intradomiciliary animals. Our new python scripts were able to detect blood meal sources in 100% of the bugs analyzed and identified nine different species of blood meal sources. Human, chicken, and dog were the main blood sources found in 78.7%, 50.4% and 44.8% of the bugs, respectively. In addition, 14% of the bugs feeding on chicken and 15% of those feeding on dogs were captured in houses with no evidence of those animals being present. This suggests a high mobility among ecotopes and houses. Two of the three main blood sources, dog and chicken, were significantly (p < 0.05) affected by domiciliary infestation risk variables, including cracks in walls, construction material and birds sleeping in the intradomicile. This suggests that these variables are important for maintaining reproducing Triatoma dimidiata populations and that it is critical to mitigate these variables in all the houses of a village for effective control of these mobile vectors.

Over-dispersed Trypanosoma cruzi parasite load in sylvatic and domestic mammals and humans from northeastern Argentina.

BACKGROUND: The distribution of parasite load across hosts may modify the transmission dynamics of infectious diseases. Chagas disease is caused by a multi-host protozoan, Trypanosoma cruzi, but the association between host parasitemia and infectiousness to the vector has not been studied in sylvatic mammalian hosts. We quantified T. cruzi parasite load in sylvatic mammals, modeled the association of the parasite load with infectiousness to the vector and compared these results with previous ones for local domestic hosts. METHODS: The bloodstream parasite load in each of 28 naturally infected sylvatic mammals from six species captured in northern Argentina was assessed by quantitative PCR, and its association with infectiousness to the triatomine Triatoma infestans was evaluated, as determined by natural or artificial xenodiagnosis. These results were compared with our previous results for 88 humans, 70 dogs and 13 cats, and the degree of parasite over-dispersion was quantified and non-linear models fitted to data on host infectiousness and bloodstream parasite load. RESULTS: The parasite loads of Didelphis albiventris (white-eared opossum) and Dasypus novemcinctus (nine-banded armadillo) were directly and significantly associated with infectiousness of the host and were up to 190-fold higher than those in domestic hosts. Parasite load was aggregated across host species, as measured by the negative binomial parameter, k, and found to be substantially higher in white-eared opossums, cats, dogs and nine-banded armadillos (range: k = 0.3-0.5) than in humans (k = 5.1). The distribution of bloodstream parasite load closely followed the "80-20 rule" in every host species examined. However, the 20% of human hosts, domestic mammals or sylvatic mammals exhibiting the highest parasite load accounted for 49, 25 and 33% of the infected triatomines, respectively. CONCLUSIONS: Our results support the use of bloodstream parasite load as a proxy of reservoir host competence and individual transmissibility. The over-dispersed distribution of T. cruzi bloodstream load implies the existence of a fraction of highly infectious hosts that could be targeted to improve vector-borne transmission control efforts toward interruption transmission. Combined strategies that decrease the parasitemia and/or host-vector contact with these hosts would disproportionally contribute to T. cruzi transmission control.

Changes in antennal gene expression underlying sensory system maturation in Rhodnius prolixus.

Triatomine bugs are the blood feeding insect vectors transmitting Chagas disease to humans, a neglected tropical disease that affects over 8 million people, mainly in Latin America. The behavioral responses to host cues and bug signals in Rhodnius prolixus are state dependent, i.e., they vary as a function of post-ecdysis age. At the molecular level, these changes in behavior are probably due to a modulation of peripheral and central processes. In the present study, we report a significant modulation of the expression of a large set of sensory-related genes. Results were generated by means of antennal transcriptomes of 5th instar larvae along the first week (days 0, 2, 4, 6 and 8) after ecdysis sequenced using the Illumina HiSeq platform. Significant age-induced changes in transcript abundance were established for more than 6120 genes (54,7% of 11,186 genes expressed) in the antenna of R. prolixus. This was especially true between the first two days after ecdysis when more than 2500 genes had their expression significantly altered. In contrast, expression profiles were almost identical between day 6 and 8, with only a few genes showing significant modulation of their expression. A total of 86 sensory receptors, odorant carriers and odorant degrading enzymes were significantly modulated across age points and clustered into three distinct expression profiles. The set of sensory genes whose expression increased with age (profile 3) may include candidates underlying the increased responsiveness to host cues shown by R. prolixus during the first days after molting. For the first time, we describe the maturation process undergone at the molecular level by the peripheral sensory system of a hemimetabolous insect.

Chagas Disease Ecology in the United States: Recent Advances in Understanding Trypanosoma cruzi Transmission Among Triatomines, Wildlife, and Domestic Animals and a Quantitative Synthesis of Vector-Host Interactions.

Chagas disease, a neglected tropical disease present in the Americas, is caused by the parasite Trypanosoma cruzi and is transmitted by triatomine kissing bug vectors. Hundreds of vertebrate host species are involved in the ecology of Chagas disease. The sylvatic nature of most triatomines found in the United States accounts for high levels of animal infections but few reports of human infections. This review focuses on triatomine distributions and animal infections in the southern United States. A quantitative synthesis of available US data from triatomine bloodmeal analysis studies shows that dogs, humans, and rodents are key taxa for feeding triatomines. Imperfect and unvalidated diagnostic tools for wildlife complicate the study of animal T. cruzi infections, and integrated vector management approaches are needed to reduce parasite transmission in nature. The diversity of animal species involved in Chagas disease ecology underscores the importance of a One Health approach for disease research and management.

Experimental infection of Rhodnius robustus Larrousse, 1927 (Hemiptera, Reduviidae, Triatominae) with Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae) IV.

Vector competence of triatomines (kissing bugs) for Trypanosoma cruzi transmission depends on the parasite-vector interaction and the genetic constitution of both. This study evaluates the susceptibility and vector competence of Rhodnius robustus experimentally infected with T. cruzi IV (TcIV). Nymphs were fed on infected mice or an artificial feeder with blood containing culture-derived metacyclic trypomastigotes (CMT) or blood trypomastigotes (BT). The intestinal contents (IC) and excreta of the insects were examined by fresh examination and kDNA-PCR. The rate of metacyclogenesis was also determined by differential counts. Fifth instar nymphs fed with CMT ingested a greater blood volume (mean of 74.5 µL) and a greater amount of parasites (mean of 149,000 CMT/µL), and had higher positivity in the fresh examination of the IC. Third instar nymphs fed with CMT had higher positivity (33.3%) in the fresh examination of the excreta. On the 20th day after infection (dai), infective metacyclic trypomastigote (MT) forms were predominant in the excreta of 3/4 experimental groups, and on the 30th dai, the different parasitic forms were observed in the IC of all the groups. Higher percentages of MT were observed in the excreta of the 5th instar nymphs group (84.1%) and in the IC of the 3rd instar nymphs group (80.0%). Rhodnius robustus presented high susceptibility to infection since all nymphs were infected, regardless of the method used for blood meal, in addition these insects demonstrated vector competence for TcIV with high rates of metacyclogenesis being evident.

Infection Rate of Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae) in Dipetalogaster maxima (Hemiptera: Reduviidae).

Chagas disease is caused by the infection of the parasite Trypanosoma cruzi (Chagas, 1909). Mexico is estimated to be among the countries with the highest rates of human infections. The southernmost region of the Baja California peninsula is home to the endemic, highly aggressive, and largest Triatominae vector, thus far described: Dipetalogaster maxima (Uhler 1894). Previous single-year studies have attempted to estimate the natural infection rate of T. cruzi in this species, none encompassing a multiyear sampling design nor a species-specific diagnostic tool. We report the infection rate based on more than 717 individuals examined via a PCR species-specific diagnosis. The infection rate of T. cruzi was of 4.4% (n = 5/112), 0.9% (n = 4/411), and 4.6% (n = 9/194) for 2016, 2017, and 2018, respectively, resulting in an infection rate of 2% across all sites and years (n = 18/717).

Biological Parameters of Two Triatoma protracta Subspecies (Hemiptera: Reduviidae).

In recent years, concerns about Chagas disease in the United States have increased. Triatomine bug (Hemiptera: Reduviidae) populations are the vectors of the parasite Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae), which causes Chagas disease, although the route of transmission is considered inefficient in United States. However, more studies on triatomine feeding and defecation behavior are needed. In this study, six related biological parameters from two populations of Triatoma protracta protracta (Uhler) and T. p. woodi (Uhler) from Mexican locations near the U.S. border were evaluated. The four population life cycles were less than 6 mo (161-171 d), with 9-10 blood meals needed to molt. Mortality rates were similar (31-38%) among the four populations. Triatoma p. woodi from Hidalgo, Coahuila was the most aggressive one. Feeding times were over 10 min, increasing with instar in all populations. Defecation behaviors varied among populations. High percentages of male and female fourth- and fifth-instar nymphs of T. p. protracta from Imuris and both populations of T. p. woodi defecated immediately after or <1 min of feeding. Lower percentages were observed for T. p. protracta from Jacumé. Because most parameters were similar among the four populations, independent of their subspecies and their geographic origin, we considered that T. p. protracta and T. p. woodi are efficient vectors of T. cruzi. In contrast, defecation patterns were noticeably different among some of the four triatomine populations studied. Our results highlight the importance of studying the biological parameters of local triatomine populations. They also contribute to increasing the knowledge of North American triatomine behavior and defecation patterns.

Roadblocks in Chagas disease care in endemic and nonendemic countries: Argentina, Colombia, Spain, and the United States. The NET-Heart project.

BACKGROUND: Chagas disease (CD) is endemic in Latin America; however, its spread to nontropical areas has raised global interest in this condition. Barriers in access to early diagnosis and treatment of both acute and chronic infection and their complications have led to an increasing disease burden outside of Latin America. Our goal was to identify those barriers and to perform an additional analysis of them based on the Inter American Society of Cardiology (SIAC) and the World Heart Federation (WHF) Chagas Roadmap, at a country level in Argentina, Colombia, Spain, and the United States, which serve as representatives of endemic and nonendemic countries. METHODOLOGY AND PRINCIPAL FINDINGS: This is a nonsystematic review of articles published in indexed journals from 1955 to 2021 and of gray literature (local health organizations guidelines, local policies, blogs, and media). We classified barriers to access care as (i) existing difficulties limiting healthcare access; (ii) lack of awareness about CD and its complications; (iii) poor transmission control (vectorial and nonvectorial); (iv) scarce availability of antitrypanosomal drugs; and (v) cultural beliefs and stigma. Region-specific barriers may limit the implementation of roadmaps and require the application of tailored strategies to improve access to appropriate care. CONCLUSIONS: Multiple barriers negatively impact the prognosis of CD. Identification of these roadblocks both nationally and globally is important to guide development of appropriate policies and public health programs to reduce the global burden of this disease.

The connection between Trypanosoma cruzi transmission cycles by Triatoma brasiliensis brasiliensis: A threat to human health in an area susceptible to desertification in the Seridó, Rio Grande do Norte, Brazil.

An outbreak of Chagas disease, possibly involving its vector Triatoma brasiliensis brasiliensis, was identified in the state of Rio Grande do Norte (RN). Given the historical significance of this vector in public health, the study aimed to evaluate its role in the transmission dynamics of the protozoan Trypanosoma cruzi in an area undergoing desertification in the Seridó region, RN, Brazil. We captured triatomines in sylvatic and anthropic ecotopes. Natural vector infection was determined using parasitological and molecular methods and we identified discrete typing units (DTUs) of T. cruzi by analyzing the COII gene of mtDNA, 24Sα rDNA, and mini-exon gene. Their blood meals sources were identified by amplification and sequencing of the mtDNA cytochrome b gene. A total of 952 T. b. brasiliensis were captured in peridomestic (69.9%) and sylvatic ecotopes (30.4%). A wide range of natural infection rates were observed in peridomestic (36.0% - 71.1%) and sylvatic populations (28.6% - 100.0%). We observed the circulation of TcI and TcII DTUs with a predominance of Tcl in sylvatic and peridomestic environments. Kerodon rupestris, rocky cavy (13/39), Homo sapiens, human (8/39), and Bos taurus, ox (6/39) were the most frequently detected blood meals sources. Thus, Triatoma b. brasiliensis is invading and colonizing the human dwellings. Furthermore, high levels of natural infection, coupled with the detection of TcI and TcII DTUs, and also the detection of K. rupestris and H. sapiens as blood meals sources of infected T. b. brasiliensis indicate a risk of T. cruzi transmission to human populations in areas undergoing desertification.

The potential risk of enzootic Trypanosoma cruzi transmission inside four training and re-training military battalions (BITER) in Colombia.

BACKGROUND: Colombia's National Army is one of the largest military institutions in the country based on the number of serving members and its presence throughout the country. There have been reports of cases of acute or chronic cases of Chagas disease among active military personnel. These may be the result of military-associated activities performed in jungles and other endemic areas or the consequence of exposure to Trypanosoma cruzi inside military establishments/facilities located in endemic areas. The aim of the present study was to describe the circulation of T. cruzi inside facilities housing four training and re-training battalions [Battalions of Instruction, Training en Re-training (BITERs)] located in municipalities with historical reports of triatomine bugs and Chagas disease cases. An entomological and faunal survey of domestic and sylvatic environments was conducted inside each of these military facilities. METHODS: Infection in working and stray dogs present in each BITER location was determined using serological and molecular tools, and T. cruzi in mammal and triatomine bug samples was determined by PCR assay. The PCR products of the vertebrate 12S rRNA gene were also obtained and subjected to Sanger sequencing to identify blood-feeding sources. Finally, we performed a geospatial analysis to evaluate the coexistence of infected triatomines and mammals with the military personal inside of each BITER installation. RESULTS: In total, 86 specimens were collected: 82 Rhodnius pallescens, two Rhodnius prolixus, one Triatoma dimidiata and one Triatoma maculata. The overall T. cruzi infection rate for R. pallescens and R. prolixus was 56.1 and 100% respectively, while T. dimidiata and T. maculata were not infected. Eight feeding sources were found for the infected triatomines, with opossum and humans being the most frequent sources of feeding (85.7%). Infection was most common in the common opossum Didelphis marsupialis, with infection levels of 77.7%. Sylvatic TcI was the most frequent genotype, found in 80% of triatomines and 75% of D. marsupialis. Of the samples collected from dogs (n = 52), five (9.6%; 95% confidence interval: 3.20-21.03) were seropositive based on two independent tests. Four of these dogs were creole and one was a working dog. The spatial analysis revealed a sympatry between infected vectors and mammals with the military population. CONCLUSIONS: We have shown a potential risk of spillover of sylvatic T. cruzi transmission to humans by oral and vectorial transmission in two BITER installations in Colombia. The results indicate that installations where 100,000 active military personnel carry out training activities should be prioritized for epidemiological surveillance of Chagas disease.

Human Blood Meals in Sylvatic Triatomines Challenges Domestic-Centered Strategies for Prevention of Trypanosoma cruzi Transmission in Ecuador.

Transmission risk of Chagas disease has been associated with human-vector contacts and triatomines colonizing dwellings, but alternative scenarios, independent of domestic colonization, are poorly documented. In the present work, we estimated the frequency of human blood meals in triatomines from domicile, peridomicile, and sylvatic environments in two endemic regions in Ecuador. Blood meal origins were identified by sequencing a cytb gene fragment. Human blood meals were detected in 42% of the triatomines among 416 analyzed, including 48% of sylvatic triatomines (both adults and nymphs). In triatomines from domicile and peridomicile, Trypanosoma cruzi infection rate was > 20%, and reached 48% in sylvatic triatomines. Human is a common source of blood for triatomines whether they live in or near dwellings in both regions, and the high rate of T. cruzi infection represents an important risk of transmission of Chagas disease. Consequently, control strategies should also take into account possible nondomestic transmission.

Triatoma sordida (Hemiptera, Triatominae) from La Paz, Bolivia: an incipient species or an intraspecific chromosomal polymorphism?

BACKGROUND: Triatoma sordida is one of the main Chagas disease vectors in Brazil. In addition to Brazil, this species has already been reported in Bolivia, Argentina, Paraguay, and Uruguay. It is hypothesized that the insects currently identified as T. sordida are a species subcomplex formed by three cytotypes (T. sordida sensu stricto [s.s.], T. sordida La Paz, and T. sordida Argentina). With the recent description of T. rosai from the Argentinean specimens, it became necessary to assess the taxonomic status of T. sordida from La Paz, Bolivia, since it was suggested that it may represent a new species, which has taxonomic, evolutionary, and epidemiological implications. Based on the above, we carried out molecular and experimental crossover studies to assess the specific status of T. sordida La Paz. METHODS: To evaluate the pre- and postzygotic barriers between T. sordida La Paz and T. sordida s.s., experimental crosses and intercrosses between F1 hybrids and between F2 hybrids were conducted. In addition, cytogenetic analyses of the F1 and F2 hybrids were applied with an emphasis on the degree of pairing between the homeologous chromosomes, and morphological analyses of the male gonads were performed to evaluate the presence of gonadal dysgenesis. Lastly, the genetic distance between T. sordida La Paz and T. sordida s.s. was calculated for the CYTB, ND1, and ITS1 genes. RESULTS: Regardless of the gene used, T. sordida La Paz showed low genetic distance compared to T. sordida s.s. (below 2%). Experimental crosses resulted in offspring for both directions, demonstrating that there are no prezygotic barriers installed between these allopatric populations. Furthermore, postzygotic barriers were not observed either (since the F1 × F1 and F2 × F2 intercrosses resulted in viable offspring). Morphological and cytogenetic analyses of the male gonads of the F1 and F2 offspring demonstrated that the testes were not atrophied and did not show chromosome pairing errors. CONCLUSION: Based on the low genetic distance (which configures intraspecific variation), associated with the absence of prezygotic and postzygotic reproductive barriers, we confirm that T. sordida La Paz represents only a chromosomal polymorphism of T. sordida s.s.

Case Report: Molecular Detection and Characterization of Trypanosoma cruzi in Ocular Tissue from Donors with Chagas Disease.

Corneal transplantation is the most frequent transplant worldwide. Tissue characteristics allow storage and transport, even between continents, increasing its accessibility around the world. Donor infection with Trypanosoma cruzi is not defined as a corneal discarding factor, although the transplant is not recommended preventively, as in any infectious diseases. Herein, by means of polymerase chain reaction (PCR) strategies, we analyzed parasite presence in ocular tissue from 10 deceased donors with Chagas diseases. Among them, positive findings were obtained in corneas, scleras, and eye muscle samples of three, two, and one donor, respectively. Moreover, among the six T. cruzi defined populations, TcV and TcVI parasites were found in some samples based on group-specific amplification strategies. Our findings point out the actual possibility of T. cruzi transmission due to corneal transplantation and makes donor's serological status knowledge mandatory regardless of graft provenance. Failing that, we suggest a posttransplant follow-up of recipients from seropositive donors.

Revisiting the hybridization processes in the Triatoma brasiliensis complex (Hemiptera, Triatominae): Interspecific genomic compatibility point to a possible recent diversification of the species grouped in this monophyletic complex.

Triatomines are hematophagous insects of great epidemiological importance, since they are vectors of the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. Triatoma brasiliensis complex is a monophyletic group formed by two subspecies and six species: T. b. brasiliensis, T. b. macromelasoma, T. bahiensis, T. juazeirensis, T. lenti, T. melanica, T. petrocchiae and T. sherlocki. The specific status of several species grouped in the T. brasiliensis complex was confirmed from experimental crossing and analysis of reproductive barriers. Thus, we perform interspecific experimental crosses between T. lenti and other species and subspecies of the T. brasiliensis complex and perform morphological analysis of the gonads and cytogenetic analysis in the homeologous chromosomes of the hybrids of first generation (F1). Besides that, we rescue all the literature data associated with the study of reproductive barriers in this monophyletic complex of species and subspecies. For all crosses performed between T. b. brasiliensis, T. b. macromelasoma, T. juazeirensis and T. melanica with T. lenti, interspecific copulas occurred (showing absence of mechanical isolation), hybrids were obtained, none of the male hybrids presented the phenomenon of gonadal dysgenesis and 100% pairing between the chromosomes homeologous of the hybrids was observed. Thus, we demonstrate that there are no pre-zygotic reproductive barriers installed between T. lenti and the species and subspecies of the T. brasiliensis complex. In addition, we demonstrate that the hybrids obtained between these crosses have high genomic compatibility and the absence of gonadal dysgenesis. These results point to reproductive compatibility between T. lenti and species and subspecies of the T. brasiliensis complex (confirming its inclusion in the complex) and lead us to suggest a possible recent diversification of the taxa of this monophyletic group.

Insecticidal efficacy of fluralaner (Bravecto®) against Triatoma brasiliensis, a major vector of Trypanosoma cruzi in Brazil.

BACKGROUND: Triatomines are responsible for the vector transmission of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Triatoma brasiliensis is the main vector of the parasite in Brazil, and dogs are an important reservoir of the parasite. The aim of this study was to evaluate the insecticidal effect of fluralaner (Bravecto®) on T. brasiliensis after a blood meal in treated dogs. METHODS: Healthy mongrel dogs (n = 8) were recruited from the Zoonoses Control Center (ZCC) in the city of Natal, Rio Grande do Norte, Brazil, and randomized into two groups, a fluralaner (Bravecto®)-treated group (n = 4) and a control group (n = 4). Colony-reared third-, fourth- and fifth-instar nymphs of T. brasiliensis nymphs (n = 10) were allowed to feed on dogs from both groups for 30-40 min, once monthly, for up to 12 months. Bug mortality was observed up to 5 days after each blood meal. RESULTS: Mortality in triatomines which had a blood meal on fluralaner (Bravecto®)-treated dogs was 100% for up to 7 months after treatment, with mortality decreasing to 66.4% after 8 months, 57% after 9 months, 35% after 10 months, 10% after 11 months and 0% after 12 months. The mortality of triatomines that fed on non-treated control dogs was always ≤ 2.5%. CONCLUSIONS: Our results suggest that fluralaner (Bravecto®) treatment of dogs induces long-term mortality of T. brasiliensis after the blood meal. This is a potential approach to be used to control vector transmission of T. cruzi, the etiological agent of Chagas disease, especially in endemic areas.