Introduction Açucena Municipality, Rio Doce Valley, State of Minas Gerais, Brazil temporarily (2001-2005) interrupted epidemiological surveillance for Chagas disease. The objective of this work was to evaluate the Chagas Disease Control Program (CDCP) in Açucena and to offer suggestions for improving local epidemiological surveillance. Methods This study was conducted in three phases: I) a serological investigation of schoolchildren aged 5 to 15 years using an enzyme-linked immunosorbent assay (ELISA) test performed on blood collected on filter paper followed by ELISA, indirect immunofluorescence (IIF) and indirect hemaglutination (IHA) on venous blood for borderline cases and those in the gray zone of reactivity; II) vector evaluation using the data obtained by local health agents during 2006-2010; and III) examination by ELISA, IIF and IHA of serum samples from the inhabitants of houses where infected Triatoma vitticeps was found and evaluation of their knowledge about Chagas disease. Results Five individuals had inconclusive results in the ELISA screening but were seronegative for Chagas disease. The triatomine evaluation revealed the presence of three species: Triatoma vitticeps, Panstrongylus megistus and Panstrongylus diasi. Triatoma vitticeps was the most prevalent and widespread, with a higher (67%) index of Trypanosoma cruzi flagellates and evidence of colonization. Most of the inhabitants of the infested houses recognized triatomines and had basic knowledge about Chagas disease. Conclusions Although T. vitticeps is not clearly associated with Chagas disease transmission, these results highlight the importance of maintaining CDCP in endemic areas and the need for greater emphasis on epidemiological surveillance, especially in areas with important vectorial changes or that have been modified by human intervention.

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.

Em Minas Gerais, Brasil, após a eliminação do Triatoma infestans, realizada pelo Programa de Controle da Doença de Chagas (PCDCh), algumas espécies, como Panstrongylus megistus, merecem maior atenção da vigilância entomológica. Com a reforma sanitária, as ações do PCDCh couberam aos municípios, e alguns têm encontrado dificuldades administrativas e operacionais para a realização e/ou manutenção do programa. O presente trabalho objetivou analisar a vigilância entomológica da doença de Chagas nos 54 municípios supervisionados pela Diretoria de Ações Descentralizadas da Saúde de Divinópolis, entre 2000 e 2003. Em 46 municípios, foram capturados 1.531 triatomíneos nesse período, sendo que 94,1% dos insetos eram exemplares de P. megistus. O índice de infecção para T. cruzi foi de 1,3% nos insetos examinados. Ao todo, foram realizadas 850 notificações distribuídas em 46 municípios, que resultaram em 835 atendimentos, o que mostra que o PCDCh está ativo e eficiente na maioria dos municípios analisados. Constatou-se que os triatomíneos continuam a invadir e eventualmente colonizar o ambiente domiciliar, ainda que em baixa densidade, demonstrando a importância da manutenção e do aprimoramento da vigilância entomológica na região.

In Minas Gerais State, Brazil, after the elimination of Triatoma infestans by the Brazilian Chagas Disease Control Program, some triatomine species, such as Panstrongylus megistus, have merited the attention of entomological surveillance authorities. After the decentralization of the Brazilian health system, certain administrative and operational difficulties have been observed in some municipalities (counties). This study aims to evaluate entomological surveillance for Chagas disease in the 54 municipalities supervised by the Division of Decentralized Health Activities in Divinópolis, Minas Gerais, from 2000 to 2003. In 46 municipalities, 1,531 triatomines were captured, of which 94.1% were P. megistus. The infection rate for T. cruzi in the vectors was 1.3%. A total of 850 reports were received and 835 site visits were conducted, showing that the program is active and efficient in the majority of the municipalities analyzed. The importance of the maintenance and improvement of entomological surveillance in the region was demonstrated, since triatomine bugs continue to invade (and can colonize) the domiciliary environment, although with low density.

Em Minas Gerais, Brasil, após a eliminação do Triatoma infestans, realizada pelo Programa de Controle da Doença de Chagas (PCDCh), algumas espécies, como Panstrongylus megistus, merecem maior atenção da vigilância entomológica. Com a reforma sanitária, as ações do PCDCh couberam aos municípios, e alguns têm encontrado dificuldades administrativas e operacionais para a realização e/ou manutenção do programa. O presente trabalho objetivou analisar a vigilância entomológica da doença de Chagas nos 54 municípios supervisionados pela Diretoria de Ações Descentralizadas da Saúde de Divinópolis, entre 2000 e 2003. Em 46 municípios, foram capturados 1.531 triatomíneos nesse período, sendo que 94,1% dos insetos eram exemplares de P. megistus. O índice de infecção para T. cruzi foi de 1,3% nos insetos examinados. Ao todo, foram realizadas 850 notificações distribuídas em 46 municípios, que resultaram em 835 atendimentos, o que mostra que o PCDCh está ativo e eficiente na maioria dos municípios analisados. Constatou-se que os triatomíneos continuam a invadir e eventualmente colonizar o ambiente domiciliar, ainda que em baixa densidade, demonstrando a importância da manutenção e do aprimoramento da vigilância entomológica na região.

In Minas Gerais State, Brazil, after the elimination of Triatoma infestans by the Brazilian Chagas Disease Control Program, some triatomine species, such as Panstrongylus megistus, have merited the attention of entomological surveillance authorities. After the decentralization of the Brazilian health system, certain administrative and operational difficulties have been observed in some municipalities (counties). This study aims to evaluate entomological surveillance for Chagas disease in the 54 municipalities supervised by the Division of Decentralized Health Activities in Divinópolis, Minas Gerais, from 2000 to 2003. In 46 municipalities, 1,531 triatomines were captured, of which 94.1% were P. megistus. The infection rate for T. cruzi in the vectors was 1.3%. A total of 850 reports were received and 835 site visits were conducted, showing that the program is active and efficient in the majority of the municipalities analyzed. The importance of the maintenance and improvement of entomological surveillance in the region was demonstrated, since triatomine bugs continue to invade (and can colonize) the domiciliary environment, although with low density.

O Triatoma sordida é uma espécie predominantemente peridomiciliar e, atualmente, a mais capturada no Brasil. Para melhor compreender a resposta deste triatomíneo às atividades de controle, uma pesquisa de infestação triatomínica foi realizada em outubro de 1993 em 12 localidades rurais do município de Porteirinha, MG, Brasil. Foram capturados 772 exemplares de T. sordida, dos quais 3,6% estavam infectados pelo Trypanosoma cruzi. Dentre as 406 unidades domiciliares pesquisadas, 34,9% estavam infestadas. Dos 695 ecótopos peridomiciliares estudados, 27,6% foram positivos para a presença de T. sordida. O estudo revelou um peridomicílio simples, com poucos ecótopos positivos por unidade domiciliar e baixa densidade triatomínica (colônias de no máximo cinco insetos). O estudo constatou uma associação entre presença de triatomíneos e ecótopos de madeira: 72,8% dos triatomíneos foram capturados neste tipo de ecótopo. Entre as unidades domiciliares positivas, 62,9% ficavam próximas do ambiente silvestre (12 a 299 m); 92,3% dos ecótopos infestados ficavam a menos de 20 m das casas. O censo de animais peridomiciliares revelou que as galinhas correspondiam a 82,7% dos animais. As unidades domiciliares infestadas foram imediatamente borrifadas com deltametrina (25 mg i.a./m²). Novas pesquisas de infestação foram feitas 7 meses (pesquisa 2) e 1 ano (pesquisa 3) após a borrifação. Na pesquisa 2 o número de triatomíneos correspondeu a 52,5% da população original e, na pesquisa 3, a 79,1% da mesma. A redução do número de triatomíneos capturados na pesquisa 2 incidiu principalmente sobre as ninfas. A grande proporção de adultos capturados nessa ocasião confirma a existência de apenas um ciclo anual do T. sordida na região. Na pesquisa 3 o aumento do número de ninfas demonstrou crescimento desta população, utilizando-se da grande disponibilidade de galinhas para alimentação. Apesar das dificuldades de borrifação e da baixa permanência do inseticida no peridomicílio, a existência de apenas um ciclo anual do triatomíneo e a lentidão na reconstituição da população original sugerem que uma borrifação anual é suficiente para controle do T. sordida. Maior eficiência poderá ser obtida com a eliminação dos esconderijos, através da substituição do material usado na construção dos anexos, principalmente a madeira.

Triatoma sordida, a predominantly peridomestic species, is currently the triatomine species most frequently collected in Brazil. To evaluate the effectiveness of control activities against this species, a survey to determine infestation rates was carried out in October 1993 in 12 rural localities in the municipality of Porteirinha, State of Minas Gerais, Brazil. In the survey, 772 T. sordida were captured, of which 3.6% were infected with Trypanosoma cruzi. Of the 406 dwellings investigated, 34.9% were infested, and 27.6% of 695 peridomiciliar ecotopes contained T. sordida. The area around the dwellings was relatively uniform, with few positive ecotopes per household and low triatomine densities (a maximum of five insects per colony). The study found an association between the presence of insects and wood: 72.8% of the insects were captured in this type of ecotope. The majority of the positive households (62.9%) were close to forests (12 to 299 m); 92.3% of the infested ecotopes were less than 20 m from the house. A census of peridomestic animals revealed that chickens were the most abundant (82.7%). All positive households found in the survey were sprayed immediately with deltamethrin (25 mg a.i./m²). New surveys were carried out 7 months (survey 2) and 12 months (survey 3) after spraying. In survey 2, the number of insects collected corresponded to 52.5% of the original total, and in survey 3, 79.1%. The decrease in population observed in survey 2 was mainly due to a reduction in the population of nymphs. The large proportion of adults captured in that survey supports the idea that T. sordida produces only a single generation per year in this region. In survey 3 the increase in the number of nymphs, attributable to the great availability of chickens as a source of food, resulted in population growth. Despite the difficulties of spraying and the short persistence of the insecticide, the slow population response of T. sordida suggests that one annual spraying is sufficient for effective control of this species. Higher effectiveness could be obtained by eliminating peridomestic hiding places, for example, by replacing wooden annexes with structures made from other materials.