A longitudinal study was conducted in Manaus, Brazil, to monitor changes of adult Aedes aegypti (L.) abundance. The objectives were to compare mosquito collections of two trap types, to characterise ...temporal changes of the mosquito population, to investigate the influence of meteorological variables on mosquito collections and to analyse the association between mosquito collections and dengue incidence. Mosquito monitoring was performed fortnightly using MosquiTRAPs (MQT) and BG-Sentinel (BGS) traps between December 2008-June 2010. The two traps revealed opposing temporal infestation patterns, with highest mosquito collections of MQTs during the dry season and highest collections of BGS during the rainy seasons. Several meteorological variables were significant predictors of mosquito collections in the BGS. The best predictor was the relative humidity, lagged two weeks (in a positive relationship). For MQT, only the number of rainy days in the previous week was significant (in a negative relationship). The correlation between monthly dengue incidence and mosquito abundance in BGS and MQT was moderately positive and negative, respectively. Catches of BGS traps reflected better the dynamic of dengue incidence. The findings help to understand the effects of meteorological variables on mosquito infestation indices of two different traps for adult dengue vectors in Manaus.
Carbon dioxide (CO2) is an important component for activating and attracting host-seeking mosquitoes. The BG-Sentinel® trap is a well-established monitoring tool for capturing Culicidae, but CO2 role ...for the trap effectiveness has not been evaluated in highly urbanised areas. The objective was to evaluate the effectiveness of BG-Sentinel traps baited with and without CO2 for capturing urban mosquitoes. Fifteen areas were selected within the city of Manaus, Brazil, where four BG-Sentinels were operated for 24 h, two of them with CO2 and two without CO2. Captured Aedes aegypti females were dissected for the determination of their parity status. A significantly higher proportion of traps (from 32-79%) were positive for female Ae. aegypti when using the BG-Sentinel with CO2 (χ2 = 11.0271, p ≤ 0.001). Catches of female Culex spp were six times higher in CO2 traps (Mann-Whitney U test = 190.5; p = 0.001). Parity rates were similar for both traps. This study showed that CO2 has primarily an enhancing effect on the efficacy of BG-Sentinel for capturing Culex spp in Manaus. For Ae. aegypti, the positivity rate of the trap was increased, when CO2 was added.
The objective of this study was to evaluate the effectiveness of Aedes aegypti mass trapping using the sticky trap MosquiTRAP (MQT) by performing a cluster randomised controlled trial in Manaus, ...state of Amazonas, Brazil. After an initial questionnaire and baseline monitoring of adult Ae. aegypti abundance with BG-Sentinel (BGS) traps in six clusters, three clusters were randomly assigned to the intervention arm where each participating household received three MQTs for mass trapping during 17 months. The remaining three clusters (control arm) did not receive traps. The effect of mass trapping on adult Ae. aegypti abundance was monitored fortnightly with BGS traps. During the last two months of the study, a serological survey was conducted. After the study, a second questionnaire was applied in the intervention arm. Entomological monitoring indicated that MQT mass trapping did not reduce adult Ae. aegypti abundance. The serological survey indicated that recent dengue infections were equally frequent in the intervention and the control arm. Most participants responded positively to questions concerning user satisfaction. According to the results, there is no evidence that mass trapping with MQTs can be used as a part of dengue control programs. The use of this sticky trap is only recommendable for dengue vector monitoring.
A sticky trap designed to capture gravid Aedes (Stegomyia) aegypti mosquitoes, MosquiTRAP, has been evaluated for monitoring this species in Brazil. However, the effects of trap densities on the ...capture rate of Ae. aegypti females and the sensitivity of vector detection are still unknown. After a preliminary study has identified areas of high and low female mosquito abundance, a set of experiments was conducted in four neighbourhoods of Belo Horizonte (state of Minas Gerais, Brazil) using densities of 1, 2, 4, 8, 16, 32 and 64 traps per block. Trap sensitivity (positive MosquiTRAP index) increased significantly when 1-8 MosquiTRAPs were installed per block in both high and low abundance areas. A strong fit was obtained for the total number of mosquitoes captured with increasing trap densities through a non-linear function (Box-Lucas) (r² = 0,994), which likely exhibits saturation towards an equilibrium level. The capacity of the Mean Female Aedes Index to distinguish between areas of high and low Ae. aegypti abundance was also investigated; the achieved differentiation was shown to be dependent on the MosquiTRAP density.
Dengue is an arbovirus that it caused by Dengue virus and transmitted by Aedes aegypti in Brazil and A. albopictus in Southeast Asia. Currently, the only available measure to break the virus ...transmission chain its fighting the vectors involved in the transmission since there is no vaccine or specific medication. Aedes albopictus in forest remnants inside urban areas may be a link in the arboviruses transmission to man, as it features eclectic behavior regarding host-seeking habit, and these places have greater proximity to humans. The fauna survey of mosquitoes and small mammals present in urban forest remnants is needed to understand the dynamics of environmental change, mainly anthropogenic character. With this set up risk factors in certain habitats, this may be related to the movement of viral agents among wild, domestic and vector. The aim of this study was to detect the presence of Dengue virus in A. albopictus and wild small mammals present in Cerrado and Atlantic Forest remnants in urban area of Minas Gerais State, Brazil. Were collected monthly (April/2011 to May/2012 ) of mosquitoes and small mammals in different areas of remaining forest in Sabará/MG. Aedes albopictus was tested by real-time PCR for detection of Dengue virus. The mammals had blood collected for serological tests (ELISA and soroneutralization) and for viral detection by conventional PCR. We collected 26 mosquitoes species and eight of small mammals. It was found that the mosquitoes species profile varied according to local and show that they prefer some kind of habitats. There were positivity for DENV-1, DENV-2 and DENV-4 in 19 pools of A. albopictus. Serological tests of mammals were positive for all serotypes in two species, rodent and marsupial. In Brazil, this is the first report of virology and serology positive for dengue-virus in small mammals. Although up to now we dont understand what is the role of these species in dengue epidemiology, it is speculated to occur on-site maintenance of the virus, making small mammals as a source of infection for mosquitoes and disease interepidemic transmission. Since small mammals can also be used as a blood source for A. albopictus females, the species can come to participate in enzootic cycles of various pathogens in these animals, including dengue. With the new framework reported the possible transmission and maintenance of dengue in areas of remnant urban forest, the scope of the disease changes and leads to questioning and a differentiated approach to disease control in front of a new framework epidemiological reported.
A dengue é uma arbovirose que, no Brasil, tem seu agente etiológico, o Dengue virus, transmitido por Aedes aegypti e por A. aegypti e A. albopictus no Sudeste Asiático. O mosquito A. albopictus, presente em áreas remanescentes de mata urbana, pode ser um elo na transmissão de arboviroses silvestres para o homem e pode estar relacionado à circulação dos agentes virais entre os animais silvestres, domésticos e vetores. O objetivo do trabalho foi detectar a presença de Dengue virus em A. albopictus e em pequenos mamíferos silvestres presentes em remanescente de Cerrado e Mata Atlântica em área urbana de Minas Gerais. Foram realizadas coletas mensais (abril/2011 a maio/2012) de culicídeos e de pequenos mamíferos em diferentes áreas remanescentes de mata presente na Unidade Fazendinha, Sabará (MG). Os mamíferos e culicídeos foram identificados com auxílio de chaves dicotômicas. Aedes albopictus foi submetido a testes de PCR em tempo real para detecção de dengue-vírus. Os mamíferos tiveram sangue coletado para realização de testes sorológicos (ELISA e Soroneutralização) além da detecção viral por PCR convencional. Foram coletadas 26 espécies de culicídeos e oito de pequenos mamíferos. Verificou-se que o perfil das espécies de mosquitos variou de acordo com os locais, indicando que mesmo em áreas pequenas os culicídeos demonstram preferências por determinados habitats. Houve positividade para DENV-1, DENV-2 e DENV-4 em 19 pools de A. albopictus. ELISA e soroneutralização realizado com soro dos mamíferos foram positivos para todos os sorotipos em duas espécies, uma de roedor e outra de marsupial. No Brasil, este é o primeiro relato de sorologia e virologia positivas para dengue-vírus em pequenos mamíferos. Apesar de ainda não se saber qual o real papel dessas espécies na epidemiologia da doença, especula-se que ocorra a manutenção local do vírus, fazendo dos pequenos mamíferos uma fonte de infecção para os mosquitos e para transmissão interepidêmica da doença. Uma vez que pequenos mamíferos também podem ser utilizados como fonte alimentar para as fêmeas de A. albopictus, a espécie pode vir a participar de ciclos enzoóticos de diversos patógenos presentes nesses mamíferos, incluindo a dengue. Com o novo quadro relatado de possível transmissão e manutenção de dengue em áreas de remanescente de mata urbana, a abrangência da doença se altera o que, consequentemente, leva ao questionamento da metodologia de controle da doença frente a um novo quadro epidemiológico relatado.
As medidas de controle existentes contra a dengue baseiam-se principalmente no combate ao vetor, Aedes aegypti, uma vez que não existem vacinas ou drogas eficazes. Para os insetos adultos, o controle ...é realizado por aplicação de inseticida nas áreas onde ocorreram casos de dengue. A armadilha BG-Sentinel® (BGS) tem sido utilizada como ferramenta de monitoramento de A. aegypti e A. Albopictus e estudos em semi-campo sugerem que esta armadilha é promissora na supressão da população da espécie. O objetivo deste trabalho foi avaliar a armadilha BG-Sentinel como ferramenta de captura de A. aegypti e A. albopictus em campo, buscando melhorar o desempenho da armadilha e verificando seu uso em massa para redução populacional destas espécies em área urbana. Os experimentos foram conduzidos na cidade de Manaus (AM) entre dezembro de 2008 e julho de 2009. Foram selecionadas 15 áreas onde em cada uma foram instaladas quatro armadilhas BGS durante 24 horas, sendo duas BGS iscadas com CO2 e duas sem. Não houve diferença significativa no número de machos e fêmeas de A. aegypti capturados nas armadilhas, independente da presença de CO2. Observou-se um aumento da captura de fêmeas de A. albopictus nas armadilhas sem CO2, contudo, este não foi significativo. Das quinze áreas anteriores, doze foram escolhidas para os experimentos de supressão populacional, sendo seis consideradas controle e seis tratamento. Cada área tratamento recebeu, em média, 74 armadilhas de intervenção que permaneceram instaladas e funcionando 24 horas por dia ao longo de todo experimento. Todas as 12 áreas receberam quatro armadilhas BGS de monitoramento que permaneciam 24 horas funcionando e foram novamente instaladas após 15 dias. A captura de fêmeas de A. aegypti pelas BGS de monitoramento nas áreas controle foi significativamente maior do que nas áreas tratamento. Em uma única área (7 - Amazonino Mendes 1) as capturas de A. albopictus foram superiores às de A. aegypti . Ao longo do experimento observou-se uma diminuição do número de A. aegypti capturados pelas armadilhas BGS de intervenção. O presente estudo demonstrou que o CO2 não aumentou a captura de A. aegypti e A. albopictus nas armadilhas BGS. A armadilha BGS apresenta potencial para reduzir a população de A. aegypti em condições de campo, podendo ser empregada futuramente como um método de controle para adultos do vetor da dengue.
PDF