Factors associated with the occurrence of dengue epidemics in Brazil: a systematic review / Factores asociados a la aparición de epidemias de dengue en Brasil: revisión sistemática / Fatores associados à ocorrência de epidemias de dengue no Brasil: uma revisão sistemática

ABSTRACT Objective. To identify and describe broadly the factors related to the occurrence of dengue epidemics in Brazil. Methods. Systematic review of studies published in Medline, Lilacs, PubMed, Cochrane, BVS, Web of Science, Scopus, and thesis and dissertations databases using descriptors cataloged in DeCs and MeSH on dengue and factors associated with the occurrence of epidemics, published from 2008 to 2018. Results. Thirty-five studies carried out in the country were selected. The epidemics recorded in Brazil were associated and/or correlated with multiple factors such as environment, socioeconomic conditions, climate, and aspects related to the vector, among others. Conclusions. Dengue epidemics are complex and multifactorial. The continuity of the vector control actions was found to be relevant to the reduction of Aedes aegypti and for disease control. To contain the spread of the disease, effective measures are needed in all sectors, including health, education, economy, population, business, and government. Actions for the early detection of cases of the disease can prevent new outbreaks of epidemics.

RESUMEN Objetivo. Determinar y describir de manera amplia los factores relacionados con la aparición de epidemias de dengue en Brasil. Métodos. Se llevó a cabo una revisión sistemática de los estudios publicados en MEDLINE, LILACS, PubMed, Cochrane, BVS, Web of Science, Scopus y en bases de datos de tesis y trabajos de final de grado con los descriptores catalogados en DeCS y MeSH sobre dengue y factores asociados con la aparición de epidemias publicados entre 2008 y 2018. Resultados. Se seleccionaron 35 estudios llevados a cabo en Brasil. Las epidemias registradas en el país se asociaron o se relacionaron con diversos factores, como el medioambiente, las condiciones socioeconómicas, el clima y aspectos relacionados con el vector, entre otros. Conclusiones. Las epidemias de dengue son complejas y multifactoriales. Se constató que la continuidad de las medidas de control de vectores es pertinente para la reducción de Aedes aegypti, así como para el control de la enfermedad. Para contener la propagación de la enfermedad son necesarias medidas eficaces en todos los sectores, como la salud, la educación, la economía, la población, las empresas y el gobierno. Las medidas de detección temprana de casos de la enfermedad pueden prevenir nuevos brotes de epidemias.

RESUMO Objetivo. Identificar e descrever, de forma geral, os fatores relacionados à ocorrência de epidemias de dengue no Brasil. Métodos. Revisão sistemática de estudos publicados entre 2008 e 2018 nas bases de dados MEDLINE, LILACS, PubMed, Cochrane, BVS, Web of Science e Scopus e em bancos de teses e dissertações, com o uso de descritores de dengue e de fatores associados à ocorrência de epidemias catalogados no portal DeCS/MeSH. Resultados. Trinta e cinco estudos realizados no Brasil foram selecionados. As epidemias registradas no país foram associadas e/ou correlacionadas a vários fatores como meio ambiente, condições socioeconômicas e climáticas, e aspectos relacionados ao vetor, entre outros. Conclusões. As epidemias de dengue são complexas e multifatoriais. Observou-se que ações contínuas de controle vetorial são essenciais para a redução da população de Aedes aegypti e o controle da doença. Para conter a propagação da dengue são necessárias medidas multissetoriais eficazes, abrangendo saúde, educação, economia, população, negócios e governo. As ações visando à detecção precoce de casos da doença contribuem para prevenir novos surtos epidêmicos.

Avaliação da armadilha ovitrampa iscada com atraente natural para o monitoramento de Aedes spp. em Dili, capital do Timor-Leste / Evaluation of the baited ovitrap with natural attractant for monitoring Aedes spp. in Dili, capital of East Timor

Resumo A dengue ocorre no Timor-Leste desde 2005, porém não existe um programa de monitoramento e controle do "Aedes aegypti". O objetivo deste estudo foi de avaliar a armadilha ovitrampa iscada com atraente natural como uma possível ferramenta para monitorar o vetor das arboviroses: Dengue (DENV), Chikungunya (CHIKV) e Zika (ZIKV). O estudo foi realizado na cidade de Dili, capital do Timor-Leste, entre as semanas epidemiológicas 32 (02/08) a 48 (02/12) de 2016. Foram instaladas 70 armadilhas Ovitrampa, em residências de 15 sucos (ruas), de quatro Postos Administrativos (bairros) da cidade. Para as analises dos dados utilizou-se os indicadores entomológicos: Índice de Positividade de Ovitrampa (IPO), Índice de Densidade Vetorial (IDV) e Índice de Densidade de Ovos (IDO). Durante o experimento foram coletados 158.904 ovos de Aedes spp.. O IPO demonstrou que todas as áreas tiveram 98% a 100% de armadilhas contendo ovos de Aedes spp.. Os indicadores IDO e IPO apresentaram correlações positivas e significativa com a temperatura. A defasagem de duas e três semanas para precipitação indicou correlação positiva significativa para IDV e IDO. Portanto, a armadilha ovitrampa é uma ferramenta que pode integrar as ações de um programa de monitoramento e controle de Aedes spp. no Timor-Leste.

Influence of breeding site availability on the oviposition behaviour of Aedes aegypti

Despite the importance of the mosquito Aedes aegypti in the transmission of arboviruses, such as yellow fever, Chikungunya fever and dengue fever, some aspects of their behaviour remain unknown. In the present study, the oviposition behaviour of Ae. aegypti females that were exposed to different densities of breeding sites (2, 4, 8 and 16) was evaluated in laboratory and semi-field conditions. The number of breeding sites that were used was proportional to the number available, but tended towards stabilisation. Females used four-six breeding sites on average, with a maximum of 11. A high percentage of eggs was observed in the water, along with the presence of a breeding site termed “favourite”, which received at least 40% of the eggs. The results are discussed in ecological, evolutionary and epidemiological approaches.

Mass trapping with MosquiTRAPs does not reduce Aedes aegypti abundance

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.

Temporal abundance of Aedes aegypti in Manaus, Brazil, measured by two trap types for adult mosquitoes

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.

A comparison of larval, ovitrap and MosquiTRAP surveillance for Aedes (Stegomyia) aegypti

In Brazil, the entomological surveillance of Aedes (Stegomyia) aegypti is performed by government-mandated larval surveys. In this study, the sensitivities of an adult sticky trap and traditional surveillance methodologies were compared. The study was performed over a 12-week period in a residential neighbourhood of the municipality of Pedro Leopoldo, state of Minas Gerais, Brazil. An ovitrap and a MosquiTRAP were placed at opposite ends of each neighbourhood block (60 traps in total) and inspections were performed weekly. The study revealed significant correlations of moderate strength between the larval survey, ovitrap and MosquiTRAP measurements. A positive relationship was observed between temperature, adult capture measurements and egg collections, whereas precipitation and frequency of rainy days exhibited a negative relationship.

Development of the BG-Malaria trap as an alternative to human-landing catches for the capture of Anopheles darlingi

Although the human-landing catch (HLC) method is the most effective for collecting anthropophilic anophelines, it has been increasingly abandoned, primarily for ethical considerations. The objective of the present study was to develop a new trap for the collection of Anopheles darlingi . The initial trials were conducted using the BG-Sentinel trap as a standard for further trap development based on colour, airflow direction and illumination. The performance of the trap was then compared with those of the CDC, Fay-Prince, counterflow geometry trap (CFG) and HLC. All trials were conducted outdoors between 06:00 pm-08:00 pm. Female specimens of An. darlingi were dissected to determine their parity. A total of 8,334 anophelines were captured, of which 4,945 were identified as An. darlingi . The best trap configuration was an all-white version, with an upward airflow and no required light source. This configuration was subsequently named BG-Malaria (BGM). The BGM captured significantly more anophelines than any of the other traps tested and was similar to HLC with respect to the number and parity of anophelines. The BGM trap can be used as an alternative to HLC for collecting anophelines.

Identification of dengue viruses in naturally infected Aedes aegypti females captured with BioGents (BG)-Sentinel traps in Manaus, Amazonas, Brazil

Introduction In Manaus, the first autochthonous cases of dengue fever were registered in 1998. Since then, dengue cases were diagnosed by the isolation of viruses 1, 2, 3, and 4. Methods One hundred eighty-seven mosquitoes were collected with BioGents (BG)-Sentinel traps in 15 urban residential areas in the Northern Zone of Manaus and processed by molecular tests. Results Infections with dengue viruses 1, 2, 3, and 4 and a case of co-infection with dengue viruses 2 and 3 were identified. Conclusions These findings corroborate the detection of dengue in clinical samples and reinforce the need for epidemiological surveillance by the Health authorities. .

Field optimisation of MosquiTRAP sampling for monitoring Aedes aegypti Linnaeus (Diptera: Culicidae)

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.

Fauna of Culicidae in rural areas of Porto Velho and the first record of Mansonia (Mansonia) flaveola (Coquillet, 1906), for the state of Rondônia, Brazil / Fauna de Culicidae em áreas rurais de Porto Velho e primeiro registro de Mansonia (Mansonia) flaveola (Coquillet, 1906), para o estado de Rondônia, Brasil

INTRODUCTION: Knowledge concerning the fauna of Culicidae in the Brazilian Amazon States contributes to current understanding of the bionomics of the insects collected and makes it possible to observe changes in the fauna over time. METHODS: The Culicidae were captured with a BG-Sentinel® trap in extra-domiciliary area of two rural regions of Porto Velho in June and July of 2007 and 2008. RESULTS: A total of 10,695 Culicidae was collected, belonging to nine genera: Coquillettidia, Culex, Mansonia, Psorophora, Aedes, Aedeomyia, Anopheles, Uranotaenia and Wyeomyia. CONCLUSIONS: The presence of Mansonia (Mansonia) flaveola was recorded in the State of Rondônia for the first time.

INTRODUÇÃO: O conhecimento da fauna de culicídeos em estados da Amazônia Brasileira auxilia no conhecimento da bionomia dos insetos obtidos, além de possibilitar a observação de modificações da fauna ao decorrer do tempo. MÉTODOS: As capturas dos culicídeos foram realizadas em área extradomiciliar de duas zonas rurais de Porto Velho, durante junho e julho, nos anos de 2007 e 2008, com a armadilha BG-Sentinel®. RESULTADOs: Foram coletados 10.695 culicídeos, distribuídos em nove gêneros: Coquillettidia, Culex, Mansonia, Psorophora, Aedes, Aedeomyia, Anopheles, Uranotaenia e Wyeomyia. CONCLUSÕES: Foi registrada pela primeira vez no estado a presença de Mansonia (Mansonia) flaveola.

Avaliação da operacionalidade da armadilha MosquiTRAP no monitoramento de Aedes aegypti / Operational evaluation of a sticky trap in the monitoring of Aedes aegypti

Objetivo: avaliar a capacidade dos agentes de saúde para identificar corretamente os mosquitos capturados pela MosquiTRAP e comparar o tempo gasto na pesquisa larvária, ovitrampa e MosquiTRAP. Metodologia: aspectos operacionais do monitoramento de Aedes aegypti foram avaliados em doze municípios das cinco regiões geográficas do Brasil. Resultados: o tempo gasto pelos agentes de saúde na vistoria da MosquiTRAP foi semelhante ao da ovitrampa (8,0 e 6,8 min., respectivamente) e ambos foram inferiores a pesquisa larvária (24,8 min.). Os agentes de saúde identificaram A. aegypti (mínimo de 97,4 por cento de acerto) e Aedes albopictus (100 por cento de acerto) em cinco dos seis municípios onde esta espécie foi registrada. O índice de pendência da MosquiTRAP em todos os municípios variou entre 0,20 por cento e 4,43 por cento. Conclusão: os resultados indicam que a ovitrampa e MosquiTRAP apresentaram vantagens em relação a pesquisa larvária com redução do tempo de vistoria das casas, implicando uma redução de custos.

Objectives: to assess the capacity of health workers to correctly identify mosquitoes captured by MosquiTRAP, and to compare the time spent on larval survey, egg trap (ovitrap) and MosquiTRAP. Methodology: operational aspects of monitoring of the Aedes aegypti were assessed in twelve municipalities in five geographic regions of Brazil. Results: time spent by health workers to inspect the MosquiTRAP was similar to ovitrap (8.0 and 6.8 minutes, respectively) and both took less than larval survey (24.8 minutes). Health workers identified A. aegypti (minimum of 97.4 percent hit) and A. albopictus (100 percent hit) in five of the six municipalities where this species was recorded. MosquiTRAP pendency index in all municipalities varied from 0.20 percent to 4.43 percent. Conclusion: results indicate that ovitrap and MosquiTRAP have advantages over larval survey in terms of reduced time spent at residences, implying cost reduction.

Preliminary evaluation of the "Dengue-MI" technology for Aedes aegypti monitoring and control / Avaliação preliminar da tecnologia "MI-Dengue" para o monitoramento e controle do Aedes aegypti

Limitations in the laboratory identification of Aedes aegypti and processing of field data based on larval surveys led to the development of the "Intelligent Dengue Monitoring" technology (MI-Dengue). MI-Dengue consists of a trap that captures gravid female Ae. aegypti, coupled with a computerized system for field data collection, transmission, and access to georeferenced maps in real time. The current study describe the first experience with a system for monitoring adult Ae. aegypti and presents the preliminary results in three municipalities that adopted MI-Dengue as a strategy to identify key areas and orient control measures. Weekly georeferenced maps and an entomological indicator (Mean Female Aedes Index) provided information on infested areas and infestation levels, color-coded according to the number of captured female Ae. aegypti, and indicated risk-free, dengue alert, and critical situations that triggered appropriate control measures. The preliminary results suggest that the adoption of this control strategy with house-to-house visits in a 200m radius of the positive trap helped reduce dengue in the municipalities that adopted the system.

As limitações na identificação do Aedes aegypti em laboratório e no processamento das informações obtidas em campo pelo método da pesquisa larvária levaram ao desenvolvimento do "Monitoramento Inteligente da Dengue" (MI-Dengue). O MI-Dengue consiste em uma armadilha que captura fêmeas grávidas de Ae. aegypti associada ao sistema informatizado de coleta, transmissão e acesso das informações de campo, e mapas georreferenciados em tempo real. O objetivo deste trabalho foi descrever pela primeira vez um sistema de monitoramento de adultos de Ae. aegypti e apresentar os resultados preliminares em três municípios que adotaram o MI-Dengue como estratégia para identificar áreas e direcionar as ações de controle. Semanalmente, mapas georreferenciados e o indicador entomológico (IMFA) forneceram informações das áreas onde os níveis de infestações, caracterizados por cores em função da quantidade de fêmeas de Ae. aegypti capturadas, indicaram situação de sem risco, alerta e crítica que desencadearam ações de controle. Os resultados preliminares sugerem que a adoção dessa estratégia de controle com visitas casa a casa em um raio de 200m da armadilha positiva contribuiu para a redução de casos de dengue nos municípios que adotaram o MI-Dengue.

Efeito da ovitrampa letal na longevidade de fêmeas de Aedes aegypti (Diptera: Culicidae) / Effect of lethal ovitrap on the longevity of females of Aedes aegypti (Diptera: Culicidae)

A armadilha de oviposição acrescida de inseticida pode funcionar como novo método de controle de fêmeas do mosquito Aedes aegypti. Fêmeas de Aedes aegypti foram colocadas em contato com ovitrampas letais envelhecidas e a mortalidade variou de 60,3 por cento a 100 por cento sendo significativo o efeito do envelhecimento das palhetas impregnadas com deltametrina no percentual de mortalidade.

Oviposition traps with added insecticide may work as a new method for controlling the females of the Aedes aegypti mosquito. Females of Aedes aegypti were placed in contact with lethal ovitraps with aging. The mortality rate ranged from 60.3 percent to 100 percent. The effect of aging the slats impregnated with deltamethrin was significant in relation to the percentage mortality among Aedes aegypti females.

Avaliação da armadilha HP iscada com diferentes taxas de liberação de octenol na captura de anofelinos (Diptera: Culicidae) em Brejo do Mutambal, Município de Varzelândia, Estado de Minas Gerais / Evaluation of the HP trap baited with different release rates of octenol for capturing anophelines (Diptera: Culicidae) in Brejo do Mutambal, municipality of Varzelândia, State of Minas Gerais

Para avaliar o papel do octenol na coleta de anofelinos foram utilizadas armadilhas HP iscadas com diferentes taxas de evaporação. Foram capturados 285 anofelinos e não houve diferença entre o número de anofelinos coletados com as armadilhas controle e as iscadas com octenol e nem entre as taxas de evaporação.

To evaluate the role of octenol in collecting anophelines, HP traps baited with different rates of evaporation. A total of 285 anophelines was captured and there was no significant difference in the numbers of anophelines captured between the control traps and the traps baited with octenol and no difference between the release rates.

Periodicidade de oviposição de fêmeas de Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae) em laboratório e campo / Periodicity of oviposition of females of Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae) in laboratory and field

O objetivo deste trabalho foi determinar o padrão gonotrófico de fêmeas de Aedes aegypti em condições de laboratório e de campo. Fêmeas copuladas e alimentadas com sangue de galinha foram transferidas para gaiolas de polipropileno e oferecidos diferentes substratos de oviposição (papel sulfite, filtro, manteiga e toalha). O papel filtro recebeu significativamente maior (40,4 por cento) deposição de ovos do que os demais substratos. Observou-se que maior (35,7 por cento dia modal) oviposição ocorreu ao terceiro dia, após alimentação sangüínea. Foi observada a oviposição das fêmeas a cada duas horas de intervalo, durante o fotoperíodo em laboratório e em campo por meio de ovitrampas. Os resultados de laboratório demonstraram que maior deposição de ovos ocorreu entre a 9ª - 12ª hora da fotofase e 1ª - 2ª hora de escotofase. Em campo maior número de ovos ocorreu entre 9ª - 12ª hora de fotofase e na 1ª - 4ª hora de escotofase. Estes resultados indicam que Aedes aegypti exibiu um padrão na periodicidade de oviposição e podem subsidiar em programas de monitoramento e ou controle do inseto vetor. Sugere-se que, em campo, por exemplo, armadilhas de oviposição (ovitrampa) devem ser instaladas no período da manhã pois as capturas ocorrem a partir do período da tarde.

The object of this work was to determine of gonotrophic diel pattern of female Aedes aegypti in laboratory and field conditions. Three day-old female mosquitoes were the fed on chicken blood and transferred to bioassay cages. Four oviposition substrates were offered: paper sulfite, filter, butter and towel. The results showed that filter paper received a significantly higher (40.4 percent) percentage of deposited eggs than the other oviposition substrates. After their first blood meal, females started to oviposit on the 3rd model day; 35.7 percent of the total number of eggs deposited. The oviposition diel patterns of females were observed every two hours during the photoperiod in the laboratory and in the field. In the laboratory, the periodicity of oviposition showed that the highest egg deposition occurred during the 9th- 12th h of photophase and 1st - 2nd h of scotophase. In the field, the highest egg deposition occurred during the 9th - 12th h of photophase and 1st - 4th h of scotophase. These results point out that Aedes aegypti showed an oviposition periodicity pattern that can subsidize monitoring and or control of vector insect. itis suggested that ovitraps should be placed in the field during the morning hours since the captures occur during afternoon.

Field evaluation of effectiveness of the BG-Sentinel, a new trap for capturing adult Aedes aegypti (Diptera: Culicidae)

In recent years, the development of new tools to gather field information about vector ecological parameters has increased. This report evaluated the BG-Sentinel Trap (BGS-Trap), a promising new attempt to improve collection of the dengue vector, Aedes aegypti. The efficacy of the BGS-Trap was compared with the CDC backpack aspirator, one of the commonest used methods for capturing adult mosquitoes. BGS-Traps captured significantly more Ae. aegypti males (chi2 = 21.774, df = 1, P < 0.05) and females (chi2 = 56.007, df = 1, P < 0.05) than CDC aspirator during all days of field collection. However, CDC aspirator was significantly more efficient to capture Culex quinquefasciatus males (chi2 = 5.681, df = 1, P < 0.05) and females (chi2 = 6.553, df = 1, P < 0.05). BGS-Traps captured host-seeking females (varying between 68.75 to 89.8 percent) in detriment of females in other behavioral and physiological stages. BGS-Traps proved to be efficient and can be used for monitoring adult mosquito populations.

Efeito da densidade larval no tamanho de adultos de Aedes aegypti criados em condições de laboratório / Effect of larvae density on adult size of Aedes aegypti reared under laboratory condictions

Para avaliar a influência da densidade larval no desenvolvimento do mosquito Aedes aegypti, foram testadas três diferentes densidades. Observou-se que em condições de alta densidade larvária e carência de alimentos houve uma redução no tamanho dos adultos e aumento na taxa de mortalidade de Aedes aegypti em condições de laboratório.