Socio-environmental factors associated with the occurrence of triatomines (Hemiptera: Reduviidae) in an endemic municipality in northern Minas Gerais, Brazil.

Triatomines are the vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. The study aimed to evaluate the association between sociodemographic and environmental factors, and changes in land use and cover, with the occurrence and abundance of triatomines by census sectors in an endemic municipality of northern Minas Gerais, Brazil. The study was conducted in Montes Claros, located in the north of Minas Gerais, Brazil. The entomological data used in the study were collected by active surveillance in the rural area from 2015 to 2019 and by passive surveillance in the urban area from 2009 to 2019. Data on sociodemographic and environmental factors and changes in land use and land cover were obtained from the urban and rural census sectors. A total of 1404 triatomines, belonging to eight species, were captured in domiciles in the rural area (2015-2019) and 277 triatomines in domiciles in the urban area (2009-2019) of the municipality of Montes Claros. The variables the number of domiciles, household economic income, pavement, NDVI, deforestation, unchanged, and anthropic proved to be positively associated with the occurrence and/or number of triatomines in census sectors, within the models. The occurrence of triatomines in the domestic environment of the municipality of Montes Claros should be considered a public health problem, as it suggests a potential risk of establishment and transmission of T. cruzi to domestic animals, farm animals, and humans.

Conhecimentos sobre a doença de Chagas entre escolares de dois municípios de Minas Gerais, Brasil / Knowledge about Chagas disease among schoolchildren from two municipalities of Minas Gerais, Brazil

Resumo Introdução: No Brasil, a vigilância entomológica da doença de Chagas (DCh) é respaldada na participação comunitária, que notifica a presença dos vetores nas habitações. Assim, a sustentabilidade desta medida de controle depende do conhecimento da população sobre os vetores. Objetivo: Avaliar o conhecimento de escolares sobre a doença de Chagas nos municípios mineiros de Itatiaiuçu (vigilância ativa) e Sabará (vigilância inativa). Método: Questionário semiestruturado foi aplicado para alunos matriculados no ensino médio em duas escolas de Sabará (rural e urbana) e uma em Itatiaiuçu (urbana). Resultados: Em geral, os alunos residentes em Sabará demonstraram conhecimento limitado acerca dos vetores, patógeno, transmissão e doença (sem diferenças relevantes quanto à localização entre área urbana e rural), quando comparados aos residentes em Itatiaiuçu, que apesar de ter uma vigilância mais atuante, também não apresentaram conhecimento totalmente satisfatório. Conclusões: Os resultados enfatizam a carência de informações sobre a DCh tanto em relação ao conhecimento acadêmico quanto às campanhas de educação firmadas pelo programa. Ações educativas para sensibilizar a comunidade e promover o conhecimento sobre esta doença mostram-se necessárias e fundamentais para a manutenção da vigilância ao longo do tempo e espaço.

Abstract Background: In Brazil, entomological surveillance of Chagas disease (ChD) is based on community participation, which notifies the presence of vectors inside their homes. Thus, the sustainability of this control measure depends on the knowledge of the population about the vectors. Objective: To evaluate the knowledge of schoolchildren about ChD in the municipalities of Itatiaiuçu (active surveillance) and Sabará (inactive surveillance). Method: A semi-structured questionnaire was given to students enrolled in two high schools in Sabará (rural and urban) and one in Itatiaiuçu (urban). Results: In general, students living in Sabará demonstrated only limited knowledge about vectors, pathogens, transmission, and disease (with no significant differences between the schools in urban and rural areas). Similarly, the schoolchildren in Itatiaiuçu, despite living in an area of active surveillance, also did not have a fully satisfactory knowledge of ChD. Conclusions: The results emphasize the lack of information about ChD, both in relation to academic knowledge and the education campaigns established by the program. Improvements in educational interventions to raise community awareness and promote knowledge about ChD are necessary and vital for maintaining vigilance against ChD over space and time.

Vigilância à saúde da doença de Chagas em municípios endêmicos de Minas Gerais: percepção e conhecimento de profissionais da vigilância entomológica / Health surveillance of Chagas disease in endemic municipalities of Minas Gerais state, Brazil: perception and knowledge of Entomological Surveillance professionals

Resumo Objetivo Traçar o perfil sociodemográfico dos agentes de combate a endemias (ACEs) dos municípios que compõem a microrregional de saúde de Itaúna, Minas Gerais; e apreender a percepção dos profissionais da vigilância entomológica sobre a doença de Chagas e serviços de saúde. Metodologia Aplicou-se um questionário semiestruturado aos ACEs e foi realizado um grupo focal com os coordenadores de endemias e digitadores. Resultados Dentre os ACEs, a maioria era do sexo feminino, entre 21 e 40 anos, com ensino médio, possuindo contrato de trabalho temporário há menos de 5 anos. Foi possível apreender: as más condições de trabalho dos ACEs, destacando-se a alta rotatividade e defasagem salarial; ausência de ações de promoção à saúde relacionadas à doença de Chagas; desarticulação entre a Atenção Primária à Saúde (APS) e Vigilância à Saúde (VS); e críticas às ações de controle da doença pós-processo de descentralização da saúde. Conclusões Há urgência na concretização da legislação inerente à natureza trabalhista e às condições de trabalho dos ACEs, bem como ao planejamento conjunto das ações de APS e VS, garantindo a atenção integral por meio de ações de promoção à saúde voltadas à população, focando especialmente a doença de Chagas, consolidando o SUS.

Abstract Objective To trace the sociodemographic profile of endemic disease combat agents (ACEs) in the municipalities that make up the health microregion of Itaúna, Minas Gerais; and apprehend the perception of entomological surveillance professionals about Chagas disease and health services. Methodology A semi-structured questionnaire was applied to the ACEs and a focus group was held with coordinators of endemic diseases and typists. Results Among the ACEs, the majority were female, between 21 and 40 years old, with high school education, with a temporary work contract for less than 5 years. It was possible to apprehend: the poor working conditions of the ACEs, highlighting the high turnover and wage gap; absence of health promotion actions related to Chagas disease; disarticulation between Primary Health Care (PHC) and Health Surveillance (HS); and criticism of disease control actions after the health decentralization process. Conclusions There is an urgent need to implement the legislation inherent to the labor nature and working conditions of the ACEs, as well as the joint planning of PHC and SV actions, guaranteeing comprehensive care through health promotion actions aimed at the population, focusing especially on Chagas disease, consolidating the SUS.

Moradores de áreas rurais de municípios mineiros endêmicos para a doença de Chagas: ideias e concepções sobre a doença, os vetores e os serviços de saúde / Residents of rural areas in municipalities of Minas Gerais endemic for Chagas disease: their ideas and conceptions about the disease, vector, and health services

Resumo Introdução A vigilância da doença de Chagas (DC), baseada na participação popular, ocorre por meio da detecção e notificação de insetos suspeitos de serem vetores da DC aos Postos de Informação de Triatomíneos (PITs). Objetivo Compreender as ideias e concepções dos moradores em áreas rurais dos municípios da Microrregião de Saúde de Itaúna (MSI) em relação a aspectos relacionados à DC, seus vetores e serviços de saúde. Método Em 2016, foram realizados quatro grupos focais nos municípios da MSI. Esses grupos focais foram gravados, transcritos e analisados utilizando a técnica de análise de conteúdo. Neste processo, identificamos e categorizamos unidades de análise tanto dentro de cada grupo focal quanto entre eles. Resultados Descobrimos que há compreensão por parte de alguns moradores sobre a natureza da transmissão da DC, as características morfológicas e hábitos dos vetores, o encaminhamento do vetor para os PITs e o diagnóstico da DC. Também encontramos relatos da ausência de intervenções educacionais e de saúde relacionadas à DC. Conclusão Compreender as concepções e ideias sobre a DC das populações em áreas endêmicas é fundamental para desenvolver futuras estratégias envolvendo a participação popular.

Abstract Background The surveillance of Chagas disease (CD) based on public participation is carried out through the detection and notification of insects suspected of being vectors of CD to Triatomine Information Posts (TIPs). Objective To understand the ideas and conceptions of residents in rural areas of the municipalities of the Micro-region of Health de Itaúna (MHI) regarding aspects related to CD, its vectors, and health services. Method In 2016, four focus groups were conducted in the municipalities of MHI. These focus groups were recorded, transcribed, and analyzed using the content analysis technique. In this process, units of analysis, both within each focus group and between them, were identified and categorized. Results It was found that some residents have a good understanding of the nature of CD transmission and of the morphological characteristics and habits of the vectors, in addition to an understanding of the forwarding of the vector to TIPs, and the diagnosis of CD. Reports of the absence of education and health interventions related to CD were also found. Conclusion Understanding the conceptions and ideas about CD of populations in endemic areas is fundamental to developing future strategies involving public participation.

High Parasitic Loads Quantified in Sylvatic Triatoma melanica, a Chagas Disease Vector.

Triatoma melanica is a sylvatic vector species in Brazil. In We aimed to characterize the Trypanosoma cruzi discrete typing units (DTUs), the parasitic loads, and the blood meal sources of insects collected in rocky outcrops in rural areas in the state of Minas Gerais. An optical microscope (OM) and kDNA-PCR were used to examine natural infection by T. cruzi, and positive samples were genotyped by conventional multilocus PCR. Quantification of the T. cruzi load was performed using qPCR, and the blood meal sources were identified by Sanger sequencing the 12S rRNA gene. A total of 141 T. melanica were captured. Of these, ~55% (61/111) and ~91% (63/69) were positive by OM and KDNA-PCR, respectively. We genotyped ~89% (56/63) of the T. cruzi-positive triatomines, with TcI (~55%, 31/56) being the most prevalent DTU, followed by TcIII (~20%, 11/56) and TcII (~7%, 4/56). Only TcI+TcIII mixed infections were detected in 10 (~18%) specimens. A wide range of variation in the parasitic loads of T. melanica was observed, with an overall median value of 104 parasites/intestine, with females having higher T. cruzi loads than N2, N4, and N5. TcII showed lower parasitic loads compared to TcI and TcIII. The OM positive diagnosis odds ratio between T. cruzi infection when the parasite load is 107 compared to 103 was approximately 29.1. The most frequent blood meal source was Kerodon rupestris (~58%), followed by Thrichomys apereoides (~18%), Wiedomys cerradensis (~8%), Galactis cuja (~8%) and Gallus gallus (~8%). Our findings characterize biological and epidemiological aspects of the sylvatic population of T. melanica in the study area, highlighting the need to extend surveillance and control to this vector.

Entomological surveillance of Chagas disease in the East of Minas Gerais region, Brazil.

BACKGROUND: After decentralizing the actions of the Chagas Disease Control Program (CDCP) in Brazil, municipalities were now responsible for control measures against this endemic, supervised by the Regional Health Superintendencies (RHS). We aimed to evaluate the recent entomological surveillance of Chagas disease in the Regional Health Superintendence of Governador Valadares (RHS/GV) from 2014 to 2019. METHODS: Triatomines captured by residents during entomological surveillance were sent to the reference laboratory, where the species and evolutionary stages were identified, place of capture, and presence of Trypanosoma cruzi. A database was created, and the following were calculated: the rate of infection by T. cruzi (overall rate and rate by species), monthly seasonality, spatial distribution of species, number of captures, and infected triatomines/health microregions. RESULTS: We identified 1,708 insects; 1,506 (88.2%) were triatomines, most were adult instars (n=1,469), and few were nymphs (n=37). The identified species were Triatoma vitticeps, Panstrongylus megistus, Panstrongylus diasi, Rhodnius neglectus, and Panstrongylus geniculatus. The first three were most frequently captured and distributed throughout the study area. Most bugs were captured intradomicile (72.5%), mainly in the second semester, between September and November, with an average infection rate of 41.5% (predominantly T. vitticeps, 49.2%). All municipalities sent triatomines, especially in the microregions of Governador Valadares. CONCLUSIONS: These data reinforce the need and importance of improving Chagas disease control measures in the region to establish active and participatory entomological surveillance.

Dynamics of Panstrongylus megistus infestation, the primary vector of Trypanosoma cruzi in Minas Gerais, Brazil.

Panstrongylus megistus is considered one of the primary species of epidemiological importance for the transmission of Chagas disease in Brazil due to its wide geographical distribution throughout the national territory, good ability to invade and colonize houses, and high rates of natural infection by the Trypanosoma cruzi. The importance of this species in Minas Gerais has been recognized since the 80s. It is responsible for the high prevalence rates of Chagas disease in the west of the state. Studies conducted in the municipality of Jaboticatubas show that P. megistus is still the most captured vector in the region, even after 40 years of uninterrupted actions of the Chagas Disease Control Program in the municipality. Despite the importance of the species, its population dynamics is little studied. Consequently, crucial genetic information such as genetic diversity and gene flow among environments have not been well characterized yet. In this context, this work presents a population genetic analysis at the microgeographic level using microsatellite markers in samples of P. megistus obtained from Jaboticatubas to better understand the infestation dynamics of the primary vector species of T. cruzi in the region. The observed and expected heterozygosity ranged from 0.26 to 0.47 and 0.47 to 0.65, respectively. Most loci presented Hardy-Weinberg disequilibrium due to the excess of homozygotes. The pairwise Fst ranged from 0.05 to 0.35, with the p value significant for all comparisons, indicating the absence of gene flow between them. The values of Fis found ranged from 0.25 to 0.52, all values of p ≤ 0.05, probably due to structured populations, inbreeding, or null alleles. The results suggest an extended stay of this species in the colonized environments, with rare dispersal to other locations. Such results differ from that observed for Triatoma brasiliensis and Triatoma dimidiata, species that present constant movement, even after colonization of the artificial environment, and are similar to the behavior of Triatoma infestans. Thus, the study reinforces the importance of continuous entomological surveillance in the areas of occurrence of P. megistus to avoid the installation and formation of new foci of household infestation in the region.

Chagas disease in the context of the 2030 agenda: global warming and vectors.

The 2030 Agenda for Sustainable Development is a plan of action for people, planet and prosperity. Thousands of years and centuries of colonisation have passed the precarious housing conditions, food insecurity, lack of sanitation, the limitation of surveillance, health care programs and climate change. Chagas disease continues to be a public health problem. The control programs have been successful in many countries in reducing transmission by T. cruzi; but the results have been variable. WHO makes recommendations for prevention and control with the aim of eliminating Chagas disease as a public health problem. Climate change, deforestation, migration, urbanisation, sylvatic vectors and oral transmission require integrating the economic, social, and environmental dimensions of sustainable development, as well as the links within and between objectives and sectors. While the environment scenarios change around the world, native vector species pose a significant public health threat. The man-made atmosphere change is related to the increase of triatomines' dispersal range, or an increase of the mobility of the vectors from their sylvatic environment to man-made constructions, or humans getting into sylvatic scenarios, leading to an increase of Chagas disease infection. Innovations with the communities and collaborations among municipalities, International cooperation agencies, local governmental agencies, academic partners, developmental agencies, or environmental institutions may present promising solutions, but sustained partnerships, long-term commitment, and strong regional leadership are required. A new world has just opened up for the renewal of surveillance practices, but the lessons learned in the past should be the basis for solutions in the future.

Different profiles and epidemiological scenarios: past, present and future.

The multiplicity of epidemiological scenarios shown by Chagas Disease, derived from multiple transmission routes of the aetiological agent, occurring on multiple geo-ecobiosocial settings determines the complexity of the disease and reveal the difficulties for its control. From the first description of the link between the parasite, the vector and its domestic habitat and the disease that Carlos Chagas made in 1909, the epidemiological scenarios of the American Trypanosomiasis has shown a dynamic increasing complexity. These scenarios changed with time and geography because of new understandings of the disease from multiple studies, because of policies change at the national and international levels and because human movements brought the parasite and vectors to new geographies. Paradigms that seemed solid at a time were broken down, and we learnt about the global dispersion of Trypanosoma cruzi infection, the multiplicity of transmission routes, that the infection can be cured, and that triatomines are not only a health threat in Latin America. We consider the multiple epidemiological scenarios through the different T. cruzi transmission routes, with or without the participation of a Triatominae vector. We then consider the scenario of regions with vectors without the parasite, to finish with the consideration of future prospects.

Monitoring Rhodnius neglectus (Lent, 1954) populations' susceptibility to insecticide used in controlling actions in urban areas northwest of São Paulo state.

BACKGROUND: Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi and can be carried by different species of triatomines, including Rhodnius neglectus, which is wild, well distributed in Brazil, and has formed colonies in palm trees located in urban areas of municipalities in the state of São Paulo. Chemical control has been routinely used to reduce population density, but each year, there has been an increase in species dispersion and density. This study aimed to evaluate the susceptibility of insects to insecticides used in control. METHODS: The reference population was collected from Araçatuba municipality, Nilce Maia. Dilutions of deltamethrin were prepared and applied to the back of the first-stage nymphs, which were biologically synchronized. The control group received pure acetone only. Mortality was assessed after 72 h. RESULTS: The mortality rate with respect to diagnostic dose was 100%. The susceptibility profile observed for this population showed RR50 ranging from 1.76 to 3.632. CONCLUSIONS: The populations were susceptible to the insecticides tested. It is possible that the insecticide residual effect on this ecotope has decreased the lifespan, and controlling failures may be the cause of recolonization in this environment.

Occurrence and spatial distribution of triatomines (Hemiptera: Reduviidae) in the urban area of the municipality of Montes Claros, Northern Minas Gerais, Brazil.

The north of the Brazilian state of Minas Gerais is classified as an area of high risk of vectorial transmission of Chagas disease (CD) or of reestablishing transmission in the home, but the Chagas disease control programme is disjointed. The study evaluated the occurrence, natural infection and the spatial distribution of species of triatomines associated with climatic variations in the urban area of Montes Claros, a municipality endemic to CD in the north of Minas Gerais, Brazil. Triatomine data were obtained from passive entomological surveillance actions of the Chagas Disease Control Program (Programa de Controle de Doença de Chagas-PCDCh), registered by the Zoonosis Control Center (Centro de Controle de Zoonoses-CCZ) from 2009 to 2019. A total of 277 triatomines belonging to eight species were collected, and of these, 203 insects were examined. It was found that 46.2% of triatomines were captured inside the home and 8.3% around the home. The natural infection rate was 6.9%; 14 specimens showed natural infection by Trypanosoma cruzi (12 females and 2 males), and of these, 13 were found in the home and one in an uninformed location. The number of triatomine records collected was significantly higher in the month of September (p = .01), and there was an inverse correlation between the number of triatomines and the relative humidity of the air (p < .001). It was verified that the highest triatomine densities are located in transition areas between urban infrastructure (32.12%) and pasture (25.72%). The diversity of species of triatomines infected with T. cruzi in residential units in urban areas in the municipality of Montes Claros is worrying, as it suggests a potential risk of transmission of the parasite to domestic animals and humans.

Entomological surveillance of Chagas disease in the East of Minas Gerais region, Brazil

ABSTRACT Background: After decentralizing the actions of the Chagas Disease Control Program (CDCP) in Brazil, municipalities were now responsible for control measures against this endemic, supervised by the Regional Health Superintendencies (RHS). We aimed to evaluate the recent entomological surveillance of Chagas disease in the Regional Health Superintendence of Governador Valadares (RHS/GV) from 2014 to 2019. Methods: Triatomines captured by residents during entomological surveillance were sent to the reference laboratory, where the species and evolutionary stages were identified, place of capture, and presence of Trypanosoma cruzi. A database was created, and the following were calculated: the rate of infection by T. cruzi (overall rate and rate by species), monthly seasonality, spatial distribution of species, number of captures, and infected triatomines/health microregions. Results: We identified 1,708 insects; 1,506 (88.2%) were triatomines, most were adult instars (n=1,469), and few were nymphs (n=37). The identified species were Triatoma vitticeps, Panstrongylus megistus, Panstrongylus diasi, Rhodnius neglectus, and Panstrongylus geniculatus. The first three were most frequently captured and distributed throughout the study area. Most bugs were captured intradomicile (72.5%), mainly in the second semester, between September and November, with an average infection rate of 41.5% (predominantly T. vitticeps, 49.2%). All municipalities sent triatomines, especially in the microregions of Governador Valadares. Conclusions: These data reinforce the need and importance of improving Chagas disease control measures in the region to establish active and participatory entomological surveillance.

Chagas disease in the context of the 2030 agenda: global warming and vectors

The 2030 Agenda for Sustainable Development is a plan of action for people, planet and prosperity. Thousands of years and centuries of colonisation have passed the precarious housing conditions, food insecurity, lack of sanitation, the limitation of surveillance, health care programs and climate change. Chagas disease continues to be a public health problem. The control programs have been successful in many countries in reducing transmission by T. cruzi; but the results have been variable. WHO makes recommendations for prevention and control with the aim of eliminating Chagas disease as a public health problem. Climate change, deforestation, migration, urbanisation, sylvatic vectors and oral transmission require integrating the economic, social, and environmental dimensions of sustainable development, as well as the links within and between objectives and sectors. While the environment scenarios change around the world, native vector species pose a significant public health threat. The man-made atmosphere change is related to the increase of triatomines' dispersal range, or an increase of the mobility of the vectors from their sylvatic environment to man-made constructions, or humans getting into sylvatic scenarios, leading to an increase of Chagas disease infection. Innovations with the communities and collaborations among municipalities, International cooperation agencies, local governmental agencies, academic partners, developmental agencies, or environmental institutions may present promising solutions, but sustained partnerships, long-term commitment, and strong regional leadership are required. A new world has just opened up for the renewal of surveillance practices, but the lessons learned in the past should be the basis for solutions in the future.

Different profiles and epidemiological scenarios: past, present and future

The multiplicity of epidemiological scenarios shown by Chagas Disease, derived from multiple transmission routes of the aetiological agent, occurring on multiple geo-ecobiosocial settings determines the complexity of the disease and reveal the difficulties for its control. From the first description of the link between the parasite, the vector and its domestic habitat and the disease that Carlos Chagas made in 1909, the epidemiological scenarios of the American Trypanosomiasis has shown a dynamic increasing complexity. These scenarios changed with time and geography because of new understandings of the disease from multiple studies, because of policies change at the national and international levels and because human movements brought the parasite and vectors to new geographies. Paradigms that seemed solid at a time were broken down, and we learnt about the global dispersion of Trypanosoma cruzi infection, the multiplicity of transmission routes, that the infection can be cured, and that triatomines are not only a health threat in Latin America. We consider the multiple epidemiological scenarios through the different T. cruzi transmission routes, with or without the participation of a Triatominae vector. We then consider the scenario of regions with vectors without the parasite, to finish with the consideration of future prospects.

Monitoring Rhodnius neglectus (Lent, 1954) populations' susceptibility to insecticide used in controlling actions in urban areas northwest of São Paulo state

ABSTRACT Background: Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi and can be carried by different species of triatomines, including Rhodnius neglectus, which is wild, well distributed in Brazil, and has formed colonies in palm trees located in urban areas of municipalities in the state of São Paulo. Chemical control has been routinely used to reduce population density, but each year, there has been an increase in species dispersion and density. This study aimed to evaluate the susceptibility of insects to insecticides used in control. Methods: The reference population was collected from Araçatuba municipality, Nilce Maia. Dilutions of deltamethrin were prepared and applied to the back of the first-stage nymphs, which were biologically synchronized. The control group received pure acetone only. Mortality was assessed after 72 h. Results: The mortality rate with respect to diagnostic dose was 100%. The susceptibility profile observed for this population showed RR50 ranging from 1.76 to 3.632. Conclusions: The populations were susceptible to the insecticides tested. It is possible that the insecticide residual effect on this ecotope has decreased the lifespan, and controlling failures may be the cause of recolonization in this environment.

Evaluation of the insecticide susceptibility profile in Cimex lectularius (Hemiptera: Cimicidae) in Belo Horizonte (Brazil).

INTRODUCTION: Since 2013, major Cimex lectularius infestations have been detected in public shelters in Belo Horizonte (Brazil). Due to this, insecticide resistance has been investigated as one of the possible causes for the failure to control bedbugs. METHODS: Cimicids were subjected to bioassays according to the World Health Organization recommendations using deltamethrin and all commercial insecticides available for control of Cimex in Brazil. RESULTS: Cimicids were deltamethrin resistant and presented indicative of resistance to other insecticides, except for propoxur 1%. CONCLUSIONS: The commercial insecticides have a limited effect on bedbug populations, which may justify the unsatisfactory control observed in the shelters studied.

Identification and characterization of microsatellite markers for population genetic studies of Panstrongylus megistus (Burmeister, 1835) (Triatominae: Reduviidae).

BACKGROUND: Panstrongylus megistus is the most important vector of Chagas disease in Brazil. Studies show that the principal factor hindering the control of triatomines is reinfestation of houses previously treated with insecticides. Studies at the microgeographic level are therefore necessary to better understand these events. However, an efficient molecular marker is not yet available for carrying out such analyses in this species. The aim of the present study was to identify and characterize microsatellite loci for future population genetic studies of P. megistus. METHODS: This study work consisted of five stages: (i) sequencing of genomic DNA; (ii) assembly and selection of contigs containing microsatellites; (iii) validation of amplification and evaluation of polymorphic loci; (iv) standardization of the polymorphic loci; and (v) verification of cross-amplification with other triatomine species. RESULTS: Sequencing of males and females generated 7,908,463 contigs with a total length of 2,043,422,613 bp. A total of 2,043,690 regions with microsatellites in 1,441,091 contigs were obtained, with mononucleotide repeats being the most abundant class. From a panel of 96 loci it was possible to visualize polymorphisms in 64.55% of the loci. Of the 20 loci genotyped, the number of alleles varied from two to nine with an average of 4.9. Cross-amplification with other species of triatomines was observed in 13 of the loci. CONCLUSIONS: Due to the high number of alleles encountered, polymorphism and the capacity to amplify from geographically distant populations, the microsatellites described here show promise for utilization in population genetic studies of P. megistus.

Bedbug salivation patterns during hematophagy in the skin of a mammalian host.

Cimex lectularius (Hemiptera:Cimicidae) infestations have increased over the past decades in several parts of the world, constituting a major urban pest with no reversion signs. The impact on human health caused by these insects, commonly known as bedbugs, is associated with their obligatory hematophagous habit. Allergies induced by hematophagous arthropod bites are related to the deposition of salivary molecules in the host tissues. Many reports of humans developing severe allergic reactions due to bedbug bites have been recorded, however, there is limited information on the salivation of bedbugs on the host, which was the objective of this study. C. lectularius females were fed on blood containing acridine orange fluorochrome, which labeled the principal salivary glands content. The salivation pattern of bedbugs was investigated using intravital microscopy during its blood meal on the ear skin of hairless mice. Saliva deposition occurred during all insect blood-feeding phases, beginning as soon as the mouthpart touched the host skin. During the probing phase, saliva was deposited in large quantities in the host dermis. In contrast, during the engorgement phase (which represents the largest blood meal of the insects), saliva was released at a much slower rate. The apparent release of saliva into the cannulated vessel and/or adjacent tissue occurs only sporadically during insect blood ingestion. However, a small area (spot) of fluorescence was detected around the proboscis tip during this feeding phase. An interesting feature of bedbugs is that they release saliva inside and outside the vessels without removing their mouthparts from the vessel lumen. This is an effective feeding strategy because it does not interrupt blood ingestion and decreases the mouthparts movements on the host's skin, minimizing the damage to tissues and contact time with the host (feeding time).