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.

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.

Occurrence of Panstrongylus megistus (Burmeister, 1835) in an area under entomological surveillance in the Southeast Region of Brazil

Abstract INTRODUCTION: Panstrongylus megistus is the main triatomine involved in the human transmission of Trypanosoma cruzi in Minas Gerais, Brazil. We analyzed the occurrence of triatomines in the Itaúna micro-regions for healthcare. METHODS: Data were collected as part of routine entomological surveillance activities, including the species identity, capture site, developmental stage, and trypanosome infection. RESULTS: In total, 503 specimens from five species were captured (495 P. megistus). Adults were mainly captured by residents inside their homes, whereas nymphs were mostly captured by public health professionals outside. CONCLUSIONS: The epidemiologically important triatomine, P. megistus, continues to persist in our study region.

Comparison of phenol-chloroform and a commercial deoxyribonucleic acid extraction kit for identification of bloodmeal sources from triatomines (Hemiptera: Reduviidae)

Abstract INTRODUCTION: Knowledge of triatomine bloodmeal sources is essential for understanding vector-host interactions in Trypanosoma cruzi transmission cycles. Expensive commercial deoxyribonucleic acid (DNA) extraction kits are widely used for bloodmeal identification. This study assessed the performance of an inexpensive phenol-chloroform DNA extraction protocol for identification of triatomine bloodmeal sources, comparing it with a commercially available kit. METHODS: Both methods were used to obtain DNA from the intestinal contents of Triatoma brasiliensis blood-fed on either Columba sp., Mus musculus, or Gallus gallus. Subsequently, the mitochondrial 12S ribosomal ribonucleic acid (rRNA) gene was amplified by polymerase chain reaction, sequenced, and compared with GenBank data. RESULTS: Twelve (80%) samples extracted with the commercial kit and four (26.7%) with phenol-chloroform were pure (according to the A260/A280 ratio). Samples extracted with phenol-chloroform, except for Columba sp. samples, had higher DNA concentration than those extracted with the commercial kit. Samples extracted using phenol-chloroform and blood-fed on G. gallus had significantly higher DNA concentration than those blood-fed on Columba sp. (p-value <0.001) and M. musculus (p-value <0.001). The 215-base-pair 12S rRNA fragment was amplified from all samples and produced reliable sequences, enabling the identification of the bloodmeal source, most of which showed identity and coverage above 95%. The phenol-chloroform method was much less expensive than the commercial kit but took considerably more time to perform. CONCLUSIONS: Our data showed that both DNA extraction methods produced reliable sequences enabling identification of triatomine bloodmeal sources but differed greatly in cost and time required.

Synanthropic triatomines (hemiptera: reduviidae): infestation, colonization, and natural infection by trypanosomatids in the state of Rio Grande do Norte, Brazil

Abstract INTRODUCTION The ecoepidemiological situation in the State of Rio Grande do Norte, Brazil is characterized by frequent invasion and colonization of domiciliary units (DUs) by several triatomine species, with high rates of natural infection by Trypanosoma cruzi. METHODS: We evaluated the possibility of vector transmission of T. cruzi based on records of the occurrence of domiciled triatomines collected by the Secretariat of State for Public Health from 2005 to 2015. During this period, 67.7% (113/167) of municipalities conducted at least one active search and 110 recorded the presence of insects in DUs. These activities were more frequent in municipalities considered to have a high and medium-level risk of T. cruzi transmission. RESULTS Of 51,569 captured triatomines, the most common species were Triatoma brasiliensis (47.2%) and T. pseudomaculata (40.2%). Colonies of T. brasiliensis, T. pseudomaculata, T. petrocchiae, Panstrongylus lutzi, and Rhodnius nasutus were also recorded in the intradomicile and peridomicile. Natural infection by trypanosomatids was detected in 1,153 specimens; the highest rate was found in R. nasutus (3.5%), followed by T. brasiliensis (2.5%) and T. pseudomaculata (2.4%). There have been high levels of colonization over the years; however, not all infested DUs have been sprayed. CONCLUSIONS: This is the first report of intradomicile and peridomicile colonization by P. lutzi. These results demonstrate the risk of new cases of infection by T. cruzi and reinforce the need for continuous entomological surveillance in the State of Rio Grande do Norte.

Species of the subfamily Triatominae Jeannel, 1919 (Hemiptera: Reduviidae) present in the Collection of Chagas Disease Vectors (FIOCRUZ-COLVEC), State of Minas Gerais

Introduction Biological collections are depositories of information on different species and contribute to the knowledge, protection, conservation and maintenance of biodiversity. Methods A list of triatomine species currently included in the Collection of Chagas Disease Vectors (FIOCRUZ-COLVEC) was prepared from the database made available by the Reference Center on Environmental Information. Results COLVEC curatorship houses 4,778 specimens of triatomines, of which 811 come from other American countries (Argentina, Bolivia, Colombia, Costa Rica, the United States of America, Guatemala, Mexico, Peru, Uruguay and Venezuela) and 3,967 are autochthonous from Brazil. Altogether, 56 species of Chagas disease vectors are represented in the COLVEC: two species of the Tribe Cavernicolini Usinger, 1944; fifteen species of the tribe Rhodniini Pinto, 1926, of which 12 are of the genus Rhodnius and 3 are of the genus Psamolestes; and 39 species of the tribe Triatomini Jeannel, 1919, represented by the genus Dipetalogaster, two species of the genus Eratyrus, two of the genus Meccus, seven of the genus Panstrongylus and 27 of the genus Triatoma. Conclusions This list provides important data on the diversity of triatomines ...

Domestic, peridomestic and wild hosts in the transmission of Trypanosoma cruzi in the Caatinga area colonised by Triatoma brasiliensis

The role played by different mammal species in the maintenance of Trypanosoma cruzi is not constant and varies in time and place. This study aimed to characterise the importance of domestic, wild and peridomestic hosts in the transmission of T. cruzi in Tauá, state of Ceará, Caatinga area, Brazil, with an emphasis on those environments colonised by Triatoma brasiliensis. Direct parasitological examinations were performed on insects and mammals, serologic tests were performed on household and outdoor mammals and multiplex polymerase chain reaction was used on wild mammals. Cytochrome b was used as a food source for wild insects. The serum prevalence in dogs was 38% (20/53), while in pigs it was 6% (2/34). The percentages of the most abundantly infected wild animals were as follows: Thrichomys laurentius 74% (83/112) and Kerodon rupestris 10% (11/112). Of the 749 triatomines collected in the household research, 49.3% (369/749) were positive for T. brasiliensis, while 6.8% were infected with T. cruzi (25/369). In captured animals, T. brasiliensis shares a natural environment with T. laurentius, K. rupestris, Didelphis albiventris, Monodelphis domestica, Galea spixii, Wiedomys pyrrhorhinos, Conepatus semistriatus and Mus musculus. In animals identified via their food source, T. brasiliensis shares a natural environment with G. spixii, K. rupestris, Capra hircus, Gallus gallus, Tropidurus oreadicus and Tupinambis merianae. The high prevalence of T. cruzi in household and peridomiciliar animals reinforces the narrow relationship between the enzootic cycle and humans in environments with T. brasiliensis and characterises it as ubiquitous.

Spraying food sources with pyrethroid to control peridomestic triatomines

Introduction We attempted to supplement traditional insecticide spraying by treating peridomiciliar food sources with a powder formulation. Methods Two groups of houses were treated with deltamethrin suspension concentrate (SC), one of which had its primary peridomestic food sources treated with deltamethrin 2P. Results Triatoma brasiliensis was the most commonly captured triatomine. Birds, dogs and rodents were the major food sources identified by the precipitin reaction; 554 domestic animals received powder treatment. A sharp reduction in infestation rates was observed in the two groups up to 360 days after spraying. Conclusion The combination SC + 2P did not improve the control of triatomines. .

Feeding behavior of Triatoma vitticeps (Reduviidae: Triatominae) in the state of Minas Gerais, Brazil

The objective of this study was to evaluate the feeding behavior of Triatoma vitticeps through the identification of its food sources and the characterization of the blood ingestion process. In addition, we aimed to verify if the saliva of this vector interferes with the perception of the host during the feedings by creating a nervous impulse. Here, we demonstrated that the T. vitticeps saliva reduces, gradually and irreversibly, the amplitude of the compound action potential of the nervous fibre, which helps decrease the perception of the insect by the host. The precipitin reaction demonstrated the feeding eclecticism of this vector, with the identification of eight food sources - most of them found simultaneously in the same insect. The analysis of the electrical signals produced by the cibarial pump during meals demonstrated that the best feeding performance of T. vitticeps nymphs that fed on pigeons is mainly due to the higher contraction frequency of the pump. The longer contact period with the host to obtain a complete meal compared with other triatominae species of the same instar could favor the occurrence of multiple blood sources in T. vitticeps under natural conditions, as it was evidenced by the precipitin test.

Caracterização da infestação domiciliar e dinâmica de populações de Triatoma vitticeps (Stal, 1859) e Trypanosoma cruzi em Itanhomi, Minas Gerais / Characterization of domiciliary infestation and population dynamics of Triatoma vitticeps (Stal, 1859) and Trypanosoma cruzi in Itanhomi, Minas Gerais

Este estudo visa determinar características biológicas, eco-epidemiológicas e a dinâmica de populações de Triatoma vitticeps e Trypanosoma cruzi no município de Itanhomi, Minas Gerais. As casas da região estudada eram de bom padrão de construção, com a presença de inúmeros animais peridomiciliares, com ausência de colonização do intradomicílio, e a presença de pequenas colônias no peridomicílio. Os estudos de biossistemática também corroboram este dado, uma vez que as metodologias empregadas não foram capazes de discriminar os insetos pelo ambiente de origem, evidenciando uma única população. Sobre o comportamento alimentar dessa espécie, vários parâmetros foram avaliados. A análise do conteúdo estomacal revelado pela reação de precipitina demonstra o ecletismo alimentar desse vetor, com a identificação de oito fontes alimentares diferentes, muitas delas encontradas simultaneamente no mesmo inseto, o que poderia representar dificuldade para obtenção do repasto sanguíneo. Esta observação é reforçada pelos resultados obtidos com o monitoramento elétrico da bomba cibarial durante a alimentação em pombos ou camundongos. As análises demonstraram que a alimentação em camundongo demanda mais esforço do que em pombos. Considerando os primeiros 10 minutos de observação pós-repasto, o número médio de dejeções eliminadas pelo T. vitticeps foi significativamente menor que o T. infestans, reforçando a menor importância epidemiológica enquanto vetor. Apesar disso, verificou-se que a saliva do T. vitticeps inibe de forma gradual e irreversível a geração do impulso nervoso, levando à diminuição da percepção do hospedeiro à picada e demonstrando seu potencial “anestésico”.

Para inferir o potencial vetorial da espécie no estado de Minas Gerais, foi realizado um levantamento histórico sobre a presença do triatomíneo em ecótopos artificiais, a partir de dados da FUNASA. O resultado obtido serviu como referência para as análises de distribuição espacial, onde as variáveis de precipitação e variação de temperatura foram selecionadas como fortes indicadores de distribuição da espécie. De fato, a eclosão dos ovos de T. vitticeps foi influenciada negativamente por umidade relativa baixa e favorecida por umidade alta. Ainda neste contexto, a higropreferência das ninfas também foi estudada. Quando recém alimentadas, as ninfas escolhem os setores mais secos da arena e quando em jejum, os setores mais úmidos, demonstrando uma relação entre a higropreferência e o estado nutricional. Através da PCR multiplex, foi possível diagnosticar e caracterizar amostras de T. cruzi sem o isolamento prévio. Apesar da alta prevalência do grupo TcI, a presença de TcII sugere a possibilidade de ocorrência de um ciclo de transmissão envolvendo homens e animais domésticos. Mais ainda, a ocorrência do grupo TcII no ambiente silvestre pode ter significado no processo de evolução e adaptação de cepas ao ciclo doméstico do parasita. Apesar de a precipitina mostrar uma participação efetiva dos roedores na dieta dos T. vitticeps analisados, estes não constituem fonte de infecção importante para os insetos, uma vez que o DNA do parasita não foi encontrado em nenhuma das 266 amostras de sangue de roedores analisadas

Caracterização da infestação domiciliar e dinâmica de populações de Triatoma vitticeps (Stal, 1859) e Trypanosoma cruzi em Itanhomi, Minas Gerais

Este estudo visa determinar características biológicas, eco-epidemiológicas e a dinâmica de populações de Triatoma vitticeps e Trypanosoma cruzi no município de Itanhomi, Minas Gerais. As casas da região estudada eram de bom padrão de construção, com a presença de inúmeros animais peridomiciliares, com ausência de colonização do intradomicílio, e a presença de pequenas colônias no peridomicílio. Os estudos de biossistemática também corroboram este dado, uma vez que as metodologias empregadas não foram capazes de discriminar os insetos pelo ambiente de origem, evidenciando uma única população. Sobre o comportamento alimentar dessa espécie, vários parâmetros foram avaliados. A análise do conteúdo estomacal revelado pela reação de precipitina demonstra o ecletismo alimentar desse vetor, com a identificação de oito fontes alimentares diferentes, muitas delas encontradas simultaneamente no mesmo inseto, o que poderia representar dificuldade para obtenção do repasto sanguíneo. Esta observação é reforçada pelos resultados obtidos com o monitoramento elétrico da bomba cibarial durante a alimentação em pombos ou camundongos. As análises demonstraram que a alimentação em camundongo demanda mais esforço do que em pombos. Considerando os primeiros 10 minutos de observação pós-repasto, o número médio de dejeções eliminadas pelo T. vitticeps foi significativamente menor que o T. infestans, reforçando a menor importância epidemiológica enquanto vetor. Apesar disso, verificou-se que a saliva do T. vitticeps inibe de forma gradual e irreversível a geração do impulso nervoso, levando à diminuição da percepção do hospedeiro à picada e demonstrando seu potencial “anestésico”.

Para inferir o potencial vetorial da espécie no estado de Minas Gerais, foi realizado um levantamento histórico sobre a presença do triatomíneo em ecótopos artificiais, a partir de dados da FUNASA. O resultado obtido serviu como referência para as análises de distribuição espacial, onde as variáveis de precipitação e variação de temperatura foram selecionadas como fortes indicadores de distribuição da espécie. De fato, a eclosão dos ovos de T. vitticeps foi influenciada negativamente por umidade relativa baixa e favorecida por umidade alta. Ainda neste contexto, a higropreferência das ninfas também foi estudada. Quando recém alimentadas, as ninfas escolhem os setores mais secos da arena e quando em jejum, os setores mais úmidos, demonstrando uma relação entre a higropreferência e o estado nutricional. Através da PCR multiplex, foi possível diagnosticar e caracterizar amostras de T. cruzi sem o isolamento prévio. Apesar da alta prevalência do grupo TcI, a presença de TcII sugere a possibilidade de ocorrência de um ciclo de transmissão envolvendo homens e animais domésticos. Mais ainda, a ocorrência do grupo TcII no ambiente silvestre pode ter significado no processo de evolução e adaptação de cepas ao ciclo doméstico do parasita. Apesar de a precipitina mostrar uma participação efetiva dos roedores na dieta dos T. vitticeps analisados, estes não constituem fonte de infecção importante para os insetos, uma vez que o DNA do parasita não foi encontrado em nenhuma das 266 amostras de sangue de roedores analisadas

Population dynamics of Triatoma vitticeps (Stål, 1859) in Itanhomi, Minas Gerais, Brazil

Taxonomic markers (head structure morphometry, isoenzymes and randon amplified polymorphism of DNA - RAPD) were used to understand the population dynamics of Triatoma vitticeps, predominant triatomine species in Itanhomi district, using samples obtained from domestic, peridomiciliary and sylvatic habitats. Morphometric analysis revealed sexual dimorphism within the three samples although specimens could not be separated according to the habitat in which they were captured. Forty-two bands were analyzed from RAPD profiles generated using four primers. A dendrogram constructed from Dice's similarity coefficient values showed that migration of the insects between the habitats has occurred, without structuring of populations. Moreover, the dendrogram obtained from the genetic distance values showed an important gene flow between the sylvatic and domestic habitats. No polymorphism was found in the electrophoretic mobility of proteins for the ten enzymes studied. Our results revealed movement of triatomines between the three habitats, suggesting that the presence of T. vitticeps in houses should not be ignored. As invasion of houses by sylvatic insects is frequent and the natural infection indices of this species are among the highest known, epidemiological vigilance studies may reveal possible changes in T. vitticeps behaviour which could present future risks to public health.