Discrepancies between Aedes aegypti identification in the field and in the laboratory after collection with a sticky trap

Currently, sticky traps are regularly employed to assist in the surveillance of Aedes aegypti infestation. We tested two alternative procedures for specimen identification performed by local health agents: directly in the field, as recommended by certain manufacturers, or after transportation to the laboratory. A total of 384 sticky traps (MosquiTRAP) were monitored monthly during one year in four geographically representative Brazilian municipalities. When the same samples were inspected in the field and in the laboratory, large differences were noted in the total number of mosquitoes recorded and in the number of specimens identified as Ae. aegypti by both procedures. Although field identification has the potential to speed vector surveillance, these results point to uncertainties in the evaluated protocol.

Updating the geographical distribution and frequency of Aedes albopictus in Brazil with remarks regarding its range in the Americas

The geographical distribution of Aedes albopictus in Brazil was updated according to the data recorded across the country over the last eight years. Countrywide house indexes (HI) for Ae. albopictus in urban and suburban areas were described for the first time using a sample of Brazilian municipalities. This mosquito is currently present in at least 59% of the Brazilian municipalities and in 24 of the 27 federal units (i.e., 26 states and the Federal District). In 34 Brazilian municipalities, the HI values for Ae. albopictus were higher than those recorded for Ae. aegypti, reaching figures as high as HI = 7.72 in the Southeast Region. Remarks regarding the current range of this mosquito species in the Americas are also presented. Nineteen American countries are currently infested and few mainland American countries have not confirmed the occurrence of Ae. albopictus. The large distribution and high frequency of Ae. albopictus in the Americas may become a critical factor in the spread of arboviruses like chikungunya in the new world.

Aedes aegypti: inseticidas, mecanismos de ação e resistência* / Aedes aegypti: inseticides, mechanisms of action and resistence

No Brasil, o Aedes aegypti é responsável pela transmissão de dengue e o Aedes albopictus, potencial vetor, está se disseminando no país. O uso de inseticidas químicos ainda é o principal componete de controle do vetor. A ação das principais classes de compostos tradicionalmente usados em Saúde Pública é descrita, assim como os mecanismos de resistência selecionados pela população do vetor. Produtos alternativos, com potencial de utilização no controle do A. aegypti, incluindo o biolarvicida Bti e alguns reguladores do desenvolvimento de insetos, também são discutidos. Pretende-se contribuir com o uso racional de inseticidas, considerando os diferentes componentes do controle integrado...

Aedes aegypti: vigilância, monitoramento da resistência e alternativas de controle no Brasil* / Aedes aegypti: surveillance, resistence monitoring, and control alternatives in Brazil

Na década de 1980, iniciou-se um processo de intensa circulação do vírus da dengue, com epidemias explosivas que têm atingido todas as regiões do Brasil. Este trabalho descreve as metodologias para vigilância do vetor atualamente utilizadas no país e contextualizada a criação da Rede Nacional de Monitoramento da Resistência de Aedes aegypti a Inseticidas em 1998, parte integrante do Programa Nacional de Controle da Dengue. São mencionadas, ainda, as medidas de controle desencadeadas pelo Ministério da Saúde em consequência das informações obtidas sobre o status de resistência aos inseticidas das populações de Aedes aegypti, incluindo a perspectiva de utilização de produtos alternativos, como os reguladores de desenvolvimento de insetos...

Aedes aegypti: histórico do controle no Brasil / Aedes aegypti: history of control in Brazil

A dengue tem se destacado como uma das mais importantes doenças reermegentes no mundo. No Brasil, a partir da década de 1980, iniciou-se um processo de intensa circulação viral, com epidemias explosivas que atingiram todas as regiões brasileiras. Atualmente, cerca de 70 por cento dos municípios brasileiros estão infestados pelo mosquito Aedes aegypti, vetor da doença no País, onde circulam três sorotipos do vírus (DEN-1, DEN-2 e DEN-3). Este trabalho faz um breve relato do histórico da dengue no Brasil, com ênfase nas políticas e programas de controle do Aedes aegypti, desde as epidemias de febre amarela urbana do início do século XX. Os aspectos fundamentais do atual Programa Nacional de Controle da Dengue também são mencionados.

Dengue is presently one of the most important reemerging diseases in the world. In Brazil, since the 1980’s, there is an intense virus circulation with epidemic bursts affecting all the regions of the country. Nowadays, roughly 70% of the Brazilian municipalities are infested with the dengue vector, Aedes aegypti, and the serotypes DEN-1, DEN-2 and DEN-3 are circulating in the country. This work presents a brief historic of the disease in Brazil, emphasizing the political strategies and programs for Aedes aegypti control since the urban yellow fever epidemics in the early 1900´s. The basic aspects of the present Brazilian Dengue Control Program are also mentioned.

Evaluation of methoprene effect on Aedes aegypti (Diptera: Culicidae) development in laboratory conditions

Several Brazilian Aedes aegypti populations are resistant to the larvicidae temephos. Methoprene, that inhibits adult emergence, is one of the alternatives envisaged by the Brazilian Dengue Control Program (PNCD). However, at Brazil vector infestation rates are measured through larvae indexes and it has been claimed that methoprene use in the field could face operational problems. In order to define a standardized protocol, methoprene effect was evaluated in laboratory conditions after continuous exposure of larvae (Rockefeller strain) to a methoprene formulation available to the PNCD. Methoprene-derived mortality occurs mainly at the pupa stage and pupa development is inversely proportional to methoprene concentration. Number and viability of eggs laid by treated and control females are equivalent. A methoprene dose-dependent delay in the development was noted; however, b correlations were found for total mortality or adult emergence inhibition if data obtained when all control mosquitoes have emerged are compared to data obtained when methoprene-treated groups finish development. The cumulative record of total methoprene-induced mortality at the time control adults emerge is proposed for routine evaluation of field populations. Mortality of all specimens, but not of larva, could account for adult emergence inhibition, confirming the inadequacy of larvae indexes to evaluate methoprene effect.

Aedes aegypti resistance to temephos during 2001 in several municipalities in the states of Rio de Janeiro, Sergipe, and Alagoas, Brazil

For more than 30 years temephos, an organophosphate insecticide, has been the sole larvicide used in Brazil in the control of Aedes aegypti. Organophosphates were also used for adult control, being replaced by pyrethroids since l999. In this same year, the Brazilian Health Foundation started the coordination of the Ae. aegypti Insecticide Resistance Monitoring Program. In the context of this program, our group was responsible for the detection of temephos resistance in a total of 12 municipalities in the states of Rio de Janeiro (RJ), Alagoas (AL), and Sergipe (SE) during 2001. In each municipality, a pool of mosquitoes collected from different districts was used, with the exception of Rio de Janeiro city, where eight districts have been separately evaluated. Exposure of larvae to the diagnostic dose of temephos revealed resistance in all localities examined, with mortality levels ranging from 4 percent (Pilares district, Rio de Janeiro, RJ) to 61.9 percent (Campos dos Goytacazes, RJ). Quantification of mortality showed resistance ratios from 6.1 (Aracaju, SE) to 16.8 (São Gonçalo, RJ and Penha district, Rio de Janeiro, RJ). The national dengue control program is presently using these data to subside insecticide resistance management.

Comparaçäo entre pesquisa larvária e armadilha de oviposiçäo, para dectecçäo de Aedes aegypti / Comparative study between larval surveys and ovitraps to monitor populations of Aedes aegypti

O estudo compara duas técnicas para a detecçäo da presença de Aedes aegypti: pesquisa de larva e armadilha de oviposiçäo. Em duas áreas do município de Salvador, Bahia, foram investigados 5.026 domicílios. As duas técnicas empregadas foram usadas simultaneamente nos mesmos domicílios. Diferentes níveis de positividade (larva e ou ovo) foram defectados entre e dentro das duas áreas. Contudo, apenas a armadilha de oviposiçäo detectou uma diferença estatística significante entre as duas áreas (z = 9,520 p < 0,001). A comparaçäo entre os Indices de Breteau, Indice Predial e Indice de Oviposiçäo revelou o último método como o mais sensível poder de detecçäo da positividade para A. aegypti. A prevalência da razäo de positividade para a armadilha de oviposiçäo foi de 3,4 e 2,1 (para áreas 1 e 2 respectivamente), quando comparada com a pesquisa de larva. A armadilha de oviposiçäo provou ser um método econômico e operacionalmente viável, sendo muito efetiva na vigilância de A. aegypti