BackgroundDuring a dengue outbreak with co-circulation of DENV-1 and -2 in the city of Boa Vista, one patient was diagnosed with DENV-4, a serotype supposed absent from Brazil for almost 30 years. The re-emergence of DENV-4 triggered the intensification of mechanical and chemical Aedes aegypti control activities in order to reduce vector density and avoid DENV-4 dissemination throughout the country.Methods/Principal FindingsVector control activities consisted of (a) source reduction, (b) application of diflubenzuron against larvae and (c) vehicle-mounted space spraying of 2% deltamethrin to eliminate adults. Control activity efficacy was monitored by comparing the infestation levels and the number of eggs collected in ovitraps before and after interventions, performed in 22 Boa Vista districts, covering an area of ∼80% of the city and encompassing 56,837 dwellings. A total of 94,325 containers were eliminated or treated with diflubenzuron. The most frequently positive containers were small miscellaneous receptacles, which corresponded to 59% of all positive breeding sites. Insecticide resistance to deltamethrin was assessed before, during and after interventions by dose-response bioassays adopting WHO-based protocols. The intense use of the pyrethroid increased fourfold the resistance ratio of the local Ae. aegypti population only six months after the beginning of vector control. Curiously, this trend was also observed in the districts in which no deltamethrin was applied by the public health services. On the other hand, changes in the resistance ratio to the organophosphate temephos seemed less influenced by insecticide in Boa Vista.ConclusionsDespite the intense effort, mosquito infestation levels were only slightly reduced. Besides, the median number of eggs in ovitraps remained unaltered after control activity intensification. The great and rapid increase in pyrethroid resistance levels of natural Ae. aegypti populations is discussed in the context of both public and domestic intensification of chemical control due to a dengue outbreak.

Apresentar um diagnóstico e constituir uma memória sobre a evolução da pandemia no Brasil, a partir de registros e análises de dados, sistemas de monitoramento e vigilância em saúde. É com esse intuito que o Observatório Covid-19 Fiocruz e a Editora Fiocruz publicam, em coedição, mais um e-book gratuito. Em três partes, que englobam um total de 25 capítulos, o título agrega os muitos desafios da comunidade científica brasileira - especialmente das equipes técnicas da Fiocruz - para a avaliação de cenários epidemiológicos diante da chegada do vírus Sars-CoV-2 ao país. Em um contexto que inclui dados reportados nos sistemas de vigilância epidemiológica, uso de modelos matemáticos e estatísticos, painéis de acompanhamento dos dados e sistemas de informação em saúde, o volume detalha os esforços e contribuições para a formulação de estratégias de mitigação e supressão da transmissão da doença. Este é o terceiro livro da série "Informação para Ação na Covid-19", que tem como objetivo reunir o conjunto de respostas, pesquisas e ações técnicas produzidas pela Fiocruz durante a pandemia. Com apoio da rede SciELO Livros, a iniciativa disponibiliza as obras exclusivamente em formato digital e acesso aberto.

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