Tecnologias integradas para controle biológico, mecânico e genético de Aedes aegypti / Integrated technologies for biological, mechanical and genetic control of Aedes aegypti

Duas tecnologias alternativas para o controle de Aedes aegypti foram avaliadas: a aplicação espacial de larvicida biológico-Bti em potenciais criadouros peridomiciliares, e a liberação de machos estéreis para inviabilização reprodutiva das fêmeas do mosquito. As ações foram realizadas pelos Agentes dos Serviços de Saúde em 15 vilas da Ilha de Fernando de Noronha, e em uma área (900 imóveis) no bairro da Várzea/Recife/Pernambuco. A efetividade dos métodos foi avaliada por indicadores entomológicos,estimados pela presença, quantidade e viabilidade de ovos do mosquito, coletados em armadilhas, e por marcadores genéticos. A aplicação de Bti, com atomizador costal, ocorreu a cada 30 dias em ambas as áreas. Uma redução importante e sustentável da população de A. aegypti,por este método, foi alcançada em 2015/2016 na Várzea e, em 2016, na Ilha, onde a remoção de 18 toneladas de resíduos sólidos em 2015 contribuiu possivelmente para os resultados. Machos esterilizados com radiação gama foram produzidos em massa no laboratório e liberados em uma das vilas da Ilha. A análise espaço-temporal dos indicadores, de dez/2015a ago/2016, revelou redução expressiva da densidade populacional do mosquito e da diversidade genética da população local. Ambas as abordagens parecem ter reduzido o contato homem-vetor e os riscos de transmissão de arboviroses na Ilha, apesar da elevada competência vetorial da população local do mosquito para os vírus Zika e Dengue. Os métodos testados se mostraram eficientes e passíveis de serem integradas às ações do SUS voltadas ao controle de A. aegypti.

Two alternative technologies were evaluated for Aedes aegypti control:the spraying of a biological larvicide (Bti) in potential peridomiciliarybreeding sites and the release of sterile males to promote reproductionblockage in wild females. Actions were carried out by Agents of theHealth Services, in 15 villages of the Fernando de Noronha Island and in 900 properties from the district of Várzea, Recife-PE. The effectiveness of both methods was evaluated by entomological indicators, estimatedby the presence, quantity and viability of eggs from the mosquito collectedin traps and through genetic markers. Bti was delivered by backpacksprayer every 30 days in both areas. A significant and sustainablereduction of the A. aegypti population as a result of this technique wasachieved in 2015/2016 in Várzea and in 2016 in the Island, where it wasstrengthened by the removal of 18 tons of solid waste in 2015. Malessterilized with gamma radiation were mass-produced in the laboratoryand released in one village of the Island. The spatiotemporal analysis ofthe indicators, from Dec/2015 to Aug/2016, revealed a significant reductionin mosquito density, which impacted on the genetic diversity of thelocal population. Both approaches seem to have reduced human-vectorcontact and the risk of arbovirus transmission in the Island, althoughlocal mosquito population presented high vector competence to Zikaand Dengue virus. These methods were efficient and could be integratedinto SUS actions directed to A. aegypti control.

Tecnologias integradas para controle biológico, mecânico e genético de Aedes aegypti / Integrated technologies for biological, mechanical and genetic control of Aedes aegypti

Duas tecnologias alternativas para o controle de Aedes aegypti foramavaliadas: a aplicação espacial de larvicida biológico-Bti em potenciaiscriadouros peridomiciliares, e a liberação de machos estéreis para inviabilizaçãoreprodutiva das fêmeas do mosquito. As ações foram realizadaspelos Agentes dos Serviços de Saúde em 15 vilas da Ilha de Fernandode Noronha, e em uma área (900 imóveis) no bairro da Várzea/Recife/Pernambuco. A efetividade dos métodos foi avaliada por indicadores entomológicos,estimados pela presença, quantidade e viabilidade de ovos domosquito, coletados em armadilhas, e por marcadores genéticos. A aplicaçãode Bti, com atomizador costal, ocorreu a cada 30 dias em ambas asáreas. Uma redução importante e sustentável da população de A. aegypti,por este método, foi alcançada em 2015/2016 na Várzea e, em 2016, naIlha, onde a remoção de 18 toneladas de resíduos sólidos em 2015 contribuiupossivelmente para os resultados. Machos esterilizados com radiaçãogama foram produzidos em massa no laboratório e liberados em umadas vilas da Ilha. A análise espaço-temporal dos indicadores, de dez/2015a ago/2016, revelou redução expressiva da densidade populacionaldo mosquito e da diversidade genética da população local. Ambas asabordagens parecem ter reduzido o contato homem-vetor e os riscos detransmissão de arboviroses na Ilha, apesar da elevada competência vetorialda população local do mosquito para os vírus Zika e Dengue. Os métodostestados se mostraram eficientes e passíveis de serem integradas às açõesdo SUS voltadas ao controle de A. aegypti(AU)

Two alternative technologies were evaluated for Aedes aegypti control:the spraying of a biological larvicide (Bti) in potential peridomiciliarybreeding sites and the release of sterile males to promote reproductionblockage in wild females. Actions were carried out by Agents of theHealth Services, in 15 villages of the Fernando de Noronha Island and in 900 properties from the district of Várzea, Recife-PE. The effectivenessof both methods was evaluated by entomological indicators, estimatedby the presence, quantity and viability of eggs from the mosquito collectedin traps and through genetic markers. Bti was delivered by backpacksprayer every 30 days in both areas. A significant and sustainablereduction of the A. aegypti population as a result of this technique wasachieved in 2015/2016 in Várzea and in 2016 in the Island, where it wasstrengthened by the removal of 18 tons of solid waste in 2015. Malessterilized with gamma radiation were mass-produced in the laboratoryand released in one village of the Island. The spatiotemporal analysis ofthe indicators, from Dec/2015 to Aug/2016, revealed a significant reductionin mosquito density, which impacted on the genetic diversity of thelocal population. Both approaches seem to have reduced human-vectorcontact and the risk of arbovirus transmission in the Island, althoughlocal mosquito population presented high vector competence to Zikaand Dengue virus. These methods were efficient and could be integratedinto SUS actions directed to A. aegypti control(AU)

Condições de saneamento básico em áreas hiperendêmicas para esquistossomose no estado de Pernambuco em 2012 / Basic sanitation conditions in schistosomiasis hyperendemic areas in Pernambuco State, Brazil, 2012 / Condiciones de saneamiento en zonas hiperendémicas de esquistosomiasis en el estado de Pernambuco en 2012: un estudio descriptivo

OBJETIVO: caracterizar as localidades hiperendêmicas para esquistossomose no estado de Pernambuco quanto às condições de saneamento e recomendar medidas de intervenção ambiental que favoreçam a sustentabilidade das ações de enfrentamento da doença. MÉTODOS: trata-se de um estudo descritivo utilizando os dados obtidos no 'Relatório das condições de saneamento das localidades hiperendêmicas para a esquistossomose e geo-helmintíases em Pernambuco', elaborado pela Secretaria Executiva de Vigilância em Saúde do estado de Pernambuco em 2012. RESULTADOS: das 119 localidades hiperendêmicas identificadas, em 72 (60,5%) foi observada inexistência de água encanada, em 110 (92,4%) não havia coleta de esgoto, e em 116 (97,5%), relatou-se ausência de tratamento do esgoto. CONCLUSÃO: as localidades hiperendêmicas avaliadas apresentaram condições de saneamento básico precárias, que contribuem para as altas prevalências da esquistossomose; por isso, torna-se necessária a sensibilização dos gestores municipais para ações efetivas de melhorias sanitárias que permitam garantir sustentabilidade no controle da esquistossomose.

OBJECTIVE: to characterize schistosomiasis hyperendemic areas in Pernambuco regarding sanitation conditions and to recommend environmental intervention measures favoring the sustainability of actions to confront the disease. METHODS: this is a descriptive epidemiological study using the data obtained in the "Report on the sanitation conditions oflocations where schistosomiasis and soil-transmitted helminths are hyperendemic in Pernambuco", prepared by Pernambuco State Executive Health Surveillance Department in 2012. RESULTS: among the 119 hyperendemic locations, 72 (60.5%) had no water supply network, 110 (92.4%) had no sewage collection network and 116 (97.5%) had no sewage treatment facilities. CONCLUSION: the hyperendemic locations had poor sanitation conditions and this contributed to high schistosomiasis prevalence. The awareness of municipal service managers therefore needs to be raised to ensure effective sanitary improvement actions to guarantee schistosomiasis control sustainability.

OBJETIVO: identificar localidades hiperendémicos de esquistosomiasis en el estado de Pernambuco basado en condiciones de saneamiento y recomendar medidas de intervención ambiental que favorezcan acciones sustentables para enfrentar la enfermedad. MÉTODOS: se realizó un estudio descriptivo, usando datos obtenidos atreves del "Informe de condiciones de saneamiento de localidades hiperendémicos de esquistosomiasis y geo-helmintiasis en Pernambuco" elaborado por la Secretaría de Vigilancia en Salud de Pernambuco en 2012. RESULTADOS: entre las 119 localidades hiperendémicas identificadas, 72 (60,5%) reportaron no tener agua por tubería, 110 (92,4%) informaron falta de recolección de aguas servidas y 116 (97,5%) falta de tratamiento de aguas residuales. CONCLUSIÓN: las localidades hiperendémicas evaluadas mostraron condiciones de saneamiento básico precarias, lo que contribuyó con la altas prevalencias de esquistosomiasis; por lo tanto, se hace necesaria la sensibilización de los gestores municipales para acciones efectivas de mejoras sanitarias que permitan garantizar la sustentabilidad en el control de la esquistosomiasis.

Susceptibility status of Culex quinquefasciatus (Diptera: Culicidae) populations to the chemical insecticide temephos in Pernambuco, Brazil.

BACKGROUND: Culex quinquefasciatus is the vector of many agents of human diseases, including Wuchereria bancrofti, the parasite that causes bancroftian filariasis, an endemic disease in Pernambuco State, Brazil. Although temephos is not currently used to control C. quinquefasciatus, the species might be under a selection process from incidental exposure to this compound. This study aimed to evaluate the susceptibility status of C. quinquefasciatus to temephos, using bioassays, and to investigate its putative resistance mechanisms through biochemical assays and screening of the G119S mutation in the acetylcholinesterase gene, which is associated with organophosphate resistance, carried out by PCR and sequencing. RESULTS: The results showed that only mosquitoes from Santa Cruz do Capibaribe (SC) had an alteration in their susceptibility status (RR = 7.2-fold), while the other populations were all susceptible to the insecticide. Biochemical assays showed increased activity for all esterases in SC, as well as evidence of acetylcholinesterase insensitivity. The G119S mutation was detected in this population with a frequency of 0.11, but it was not found in the remaining populations. CONCLUSION: These data show that mechanisms of temephos resistance have been selected in natural C. quinquefasciatus populations from Pernambuco, which could undermine future control actions.

Stability of Culex quinquefasciatus resistance to Bacillus sphaericus evaluated by molecular tools.

Bacillus sphaericus binary toxin action on Culex quinquefasciatus larvae relies on the binding to Cqm1alpha-glucosidases, which act as midgut receptors. Resistance of two laboratory-selected colonies is associated with the allele cqm1(REC) that prevents Cqm1 expression as membrane-bound molecules. This study evaluated stability of resistance after the interruption of selection pressure and introduction of susceptible individuals in these colonies. Bioassays showed that frequency of resistant larvae did not decrease throughout 11 generations, under these conditions, and it was associated to a similar frequency of larvae lacking the Cqm1alpha-glucosidase receptor, detected by in gel enzymatic assays. Direct screening of the cqm1(REC) allele, by specific PCR, showed that its frequency remained stable throughout 11 generations. Parental resistant colony did not display biological costs regarding fecundity, fertility and pupal weight and data from susceptibility assays, enzymatic assays and PCR screening showed that cqm1(REC) was not disfavored in competition with the susceptible allele and persisted in the progenies, in the lack of selection pressure. Characterization of molecular basis of resistance is essential for developing diagnostic tools and data have relevant implication for the establishment of strategies for resistance management.

Detection of an allele conferring resistance to Bacillus sphaericus binary toxin in Culex quinquefasciatus populations by molecular screening.

The activity of the Bacillus sphaericus binary (Bin) toxin on Culex quinquefasciatus larvae depends on its specific binding to the Cqm1 receptor, a midgut membrane-bound alpha-glucosidase. A 19-nucleotide deletion in the cqm1 gene (cqm1(REC)) mediates high-level resistance to Bin toxin. Here, resistance in nontreated and B. sphaericus-treated field populations of C. quinquefasciatus was assessed through bioassays as well as a specific PCR assay designed to detect the cqm1(REC) allele in individual larvae. Resistance ratios at 90% lethal concentration, gathered through bioassays, were close to 1 and indicate that the selected populations had similar levels of susceptibility to B. sphaericus, comparable to that of a laboratory colony. A diagnostic PCR assay detected the cqm1(REC) allele in all populations investigated, and its frequency in two nontreated areas was 0.006 and 0.003, while the frequency in the B. sphaericus-treated population was significantly higher. Values of 0.053 and 0.055 were detected for two distinct sets of samples, and homozygote resistant larvae were found. Evaluation of Cqm1 expression in individual larvae through alpha-glucosidase assays corroborated the allelic frequency revealed by PCR. The data from this study indicate that the cqm1(REC) allele was present at a detectable frequency in nontreated populations, while the higher frequency in samples from the treated area is, perhaps, correlated with the exposure to B. sphaericus. This is the first report of the molecular detection of a biolarvicide resistance allele in mosquito populations, and it confirms that the PCR-based approach is suitable to track such alleles in target populations.