Avaliação do conhecimento sobre a doença de Chagas em escolares das zonas rural e urbana de municípios endêmicos em Minas Gerais / Assessment of knowledge about Chagas disease in schoolchildren in rural and urban areas of endemic municipalities in Minas Gerais state, Brazil

Resumo O objetivo deste estudo foi avaliar o conhecimento de escolares do ensino médio de três escolas localizadas em municípios mineiros endêmicos para a doença de Chagas e extrair informações relativas à sua percepção em relação aos aspectos gerais, biológicos, clínicos e epidemiológicos da doença, do vetor e controle entomológico da doença de Chagas, além de comparar o conhecimento dos participantes em função da localização das escolas (zona rural ou urbana). Para isso, aplicou-se um questionário semiestruturado a 68 alunos. Todos os participantes já ouviram falar a respeito da doença de Chagas, afirmando ter adquirido esse conhecimento, sobretudo, com familiares e escola. Além disso, muitos participantes demonstraram conhecer os hábitos dos vetores, tais como hematofagia e fontes alimentares. Não houve associação clara entre o perfil de urbanização e o conhecimento dos participantes. No entanto, alunos da zona urbana apresentaram menos conhecimento prático a respeito dos triatomíneos e aspectos relativos à transmissão da doença, em relação aos alunos da zona mais "ruralizada". Sugere-se o aprofundamento do tema nos currículos escolares do ensino médio e a necessidade de elaboração de ações de educação em saúde voltadas à vigilância entomológica da doença de Chagas nesses municípios e, provavelmente, em outras regiões do Brasil.

Abstract This study aimed to evaluate the knowledge of high school students from three schools located in endemic municipalities of Minas Gerais to Chagas disease and to extract information related to their perception regarding the general, biological, clinical and epidemiological aspects of the disease, vector and entomological control of Chagas disease, in addition to comparing the knowledge of participants according to the location of schools (rural or urban area). For this, a semi-structured questionnaire was applied to 68 students. All participants have heard about Chagas disease, stating that they have acquired this knowledge, especially with family members and school. In addition, many participants demonstrated to know the habits of vectors, such as hematophagy and dietary sources. There was no clear association between the urbanization profile and the participants' knowledge. However, students from the urban area presented less practical knowledge about triatoins and aspects related to the transmission of the disease, in relation to students in the most "ruralized" area. It is suggested the deepening of the theme in high school curricula and the need to develop health education actions aimed at entomological surveillance of Chagas disease in these municipalities and, probably, in other Brazilian regions.

Description of an amazing nest of Caatinga Cachalote Pseudoseisura cristata infested by Psammolestes tertius in Tauá, state of Ceará, Northeastern Brazil

Psammolestes tertius Lent & Jurberg 1965 is a triatomine species part of the tribe Rhodniini. It is only wild and found in bird nests, mostly of the Furnariidae family. This work describes the amazing infestation of a nest of Pseudoseisura cristata in the municipality of Taua, Ceará. The nest harbored a colony with about 40 specimens of P. tertius in all evolutionary stages, all negative for trypanosomatids. A rodent of the species Wiedomys pyrrhorhinos was seen running away from the nest. The materials used to build the nest included the typical natural wigs, and various anthropogenic materials such as razor blades, shaver, fork, sunglasses, metal fragments, fragments of plastic objects, wire, barbed wire, plastic sandal straps, paper, plastic lid, pieces of plastic bags, gas cylinder label, large feathers and the exuviae of a snake.

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.

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.

Comparative developmental and susceptibility to insecticide of Bolivian and Brazilian populations of Triatoma infestans

The triatomine bug Triatoma infestans probably originated in Bolivia and dispersed passively over wide areas of South America, where it is the principal vector of Trypanosoma cruzi. In the region of its probable origin this species shows colonization in two different ecotopes, so that it may be encountered in sylvatic as well as in artificial habitats. The sylvatic colonization pattern is not observed in the rest of its range, where T. infestans is exclusive to man-made habitats. The objective of this study was to compare several aspects of two T. infestans populations, one from Minas Gerais (Brazil) and the other from the Cochabamba Valley (Bolivia), with a view to elucidate the factors associated with the different colonization patterns observed for this species. The differences between the developmental cycle, weight, capacity to ingest blood and mortality rate of first instar nymphs should indicate more fragility of Brazilian population that may be related to its elimination possibility

Characterization of Rhodnius neglectus from two regions of Brazil using isoenzymes, genitalia morphology and morphometry

Among the triatomines considered as secondary in the epidemiology of Chagas disease, Rhodnius neglectus is frequently captured in artificial ecotopes, especially peridomiciliary ones, rarely producing colonies indoors. Nevertheless, the presence of breeding colonies in houses was unquestionably demonstrated in some areas of the State of Goiás, Brazil. Previous isoenzyme comparisons of this species with morphologically close triatomines, such as R. prolixus,R. robustuts or R. nasutus, did not produce definitive conclusions because of doubt about the geographical origin of the R. neglectus. We present here, for the first time, the isoenzyme profile of topotypes of R. neglectus. In addition, wild caught specimens from the type locality, Uberaba (Minas Gerais, Brazil), were compared to wild caught specimens from Jaraguá (Goiás, Brazil), where R. neglectus is more frequently reported invading houses. We used isoenzyme, morphology and morphometry analysis. Neither morphological nor enzymatic differences were found between areas, but metric, size-related divergence was evidenced between them.

Variations of the external male genitalia in three populations of Triatoma infestans Klug, 1834

Triatoma infestans is the triatomine that presents the greatest dispersion area in South America. However, it is not known whether the original characteristics of this insect remained in its long dispersion process. The purpose of this work was to study comparatively the external male genitalia of insects from diferent populations of T. infestans, two from Brazil (Minas Gerais and Bahia) and one from Bolivia (Cochabamba Valley), and to investigate the correlation between the morphological and behavioral variations. Differences were observed in one of the structures of the external genitalia (endosoma process) that could be used to characterize the insects from the three populations studied.