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1.
Rev Soc Bras Med Trop ; 53: e20190504, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267458

RESUMO

INTRODUCTION: The study of the landscape ecology, biological microhabitat, and epidemiological implications for the distribution of the main vectors Aedes aegypti and Aedes albopictus contribute to the prevention and control actions regarding the diseases they transmit. METHODS: This study sought to assess data on positive properties of the vector control program activities from 1998 to 2010. An entomological survey was also carried out on a sample of buildings collecting larvae and pupae from containers between October and April (spring / summer) from 2002 to 2005. We assessed the physico-chemical data of the water in 20% of positive containers. The vegetation and urbanization were assessed with the aid of satellite images and microenvironments were classified as urbanized, woods, and shrubs. The data were analyzed using statistical and geoprocessing software. RESULTS: Ae. aegypti and Ae. albopictus colonized all types of microhabitats and microenvironments, predominantly in the urbanized area, in isolation and in coexistence. The microhabitat of Ae. aegypti showed a temperature gradient greater than that of Ae. albopictus, and there was an association with urbanized areas for the first species and wooded areas for the last species. CONCLUSIONS: Landscape ecology and intra-urban differences favor different microclimates, which contribute to the coexistence of species in the urban environment in an area close to the forest, raising the risk of other arbovirus infections in urban areas. The ecological niche should be considered for Ae. albopictus. Entomological and virologic monitoring are suggested as arbovirus surveillance actions in urban infested centers near preserved forests.


Assuntos
Aedes/fisiologia , Ecossistema , Mosquitos Vetores/fisiologia , Aedes/classificação , Distribuição Animal , Animais , Infecções por Arbovirus/transmissão , Brasil , Mosquitos Vetores/classificação , Densidade Demográfica , Estações do Ano , Análise Espacial , População Urbana
2.
Rev Soc Bras Med Trop ; 53: e20190185, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187334

RESUMO

INTRODUCTION: Aedes aegypti and Culex quinquefasciatus are vector species responsible for the transmission of important arboviruses. METHODS: Adult mosquitoes were collected in the urban areas of four municipalities in Mato Grosso within 1 year. RESULTS: A total of 19,110 mosquitoes were collected. Among them, 16,578 (86,8%) were C. quinquefasciatus (44% female and 56% male); 2,483 (13%), A. (Stegomyia) aegypti (54% female and 46% male); and 49 (0,30%), from the genus Psorophora, Anopheles, Coquilettidia, and Sabethes. A significant correlation was observed between the number of mosquitoes from all species and dew point (female mosquitoes, p = 0.001; male mosquitoes, p = 0.001). CONCLUSIONS: The results of this study may be used as environmental indicators of mosquito populations.


Assuntos
Aedes/fisiologia , Clima , Culex/fisiologia , Mosquitos Vetores/fisiologia , Animais , Brasil , Feminino , Masculino , População Urbana
5.
PLoS One ; 15(1): e0227407, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31951601

RESUMO

Mosquitoes are responsible for the transmission of major pathogens worldwide. Modelling their population dynamics and mapping their distribution can contribute effectively to disease surveillance and control systems. Two main approaches are classically used to understand and predict mosquito abundance in space and time, namely empirical (or statistical) and process-based models. In this work, we used both approaches to model the population dynamics in Reunion Island of the 'Tiger mosquito', Aedes albopictus, a vector of dengue and chikungunya viruses, using rainfall and temperature data. We aimed to i) evaluate and compare the two types of models, and ii) develop an operational tool that could be used by public health authorities and vector control services. Our results showed that Ae. albopictus dynamics in Reunion Island are driven by both rainfall and temperature with a non-linear relationship. The predictions of the two approaches were consistent with the observed abundances of Ae. albopictus aquatic stages. An operational tool with a user-friendly interface was developed, allowing the creation of maps of Ae. albopictus densities over the whole territory using meteorological data collected from a network of weather stations. It is now routinely used by the services in charge of vector control in Reunion Island.


Assuntos
Aedes/fisiologia , Modelos Biológicos , Controle de Mosquitos , Mosquitos Vetores/fisiologia , Animais , Temperatura Alta , Humanos , Dinâmica Populacional , Chuva
6.
Proc Natl Acad Sci U S A ; 117(1): 708-716, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31871198

RESUMO

Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoes-emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethyl-meta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors.


Assuntos
Aedes/fisiologia , Comportamento Apetitivo/fisiologia , Percepção Olfatória/fisiologia , Orchidaceae/fisiologia , Polinização/fisiologia , Animais , Comportamento Apetitivo/efeitos dos fármacos , Antenas de Artrópodes/citologia , Antenas de Artrópodes/fisiologia , Encéfalo/fisiologia , DEET/farmacologia , Feminino , Repelentes de Insetos/farmacologia , Masculino , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/fisiologia , Odorantes , Percepção Olfatória/efeitos dos fármacos , Neurônios Receptores Olfatórios/fisiologia , Polinização/efeitos dos fármacos
7.
Parasitol Res ; 119(2): 403-410, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31873769

RESUMO

Aedes japonicus japonicus is endemic in a number of countries in eastern Asia but has been accidently introduced into many regions of the world including Europe. It was first detected in Hungary in 2012. In 2017, robust populations of the species were found at Lake Balaton, one of the most important tourist destinations in Central Europe. Based on the experience gathered in the above localities, habitat requirements, dispersion abilities and human biting behaviour of the species were studied in western Hungary during 2017 and 2018. Our results show that (a) a few years after its detection at the Slovenian-Hungarian border, Ae. j. japonicus is widespread in at least two-thirds of the western half of Hungary; (b) the species spreads quickly in ecological corridors formed by mosaics of rural areas, detached houses, gardens and small forest patches; (c) Ae. j. japonicus occupies artificial containers; (d) expansion of the species into new areas is slowed by extensive closed forest patches.


Assuntos
Aedes/fisiologia , Mordeduras e Picadas de Insetos/epidemiologia , Espécies Introduzidas/estatística & dados numéricos , Animais , Ecossistema , Extremo Oriente , Florestas , Humanos , Hungria/epidemiologia , Lagos
8.
Artigo em Inglês | MEDLINE | ID: mdl-31861276

RESUMO

: Numerous urban villages (UVs) with substandard living conditions that cause people to live there with vulnerability to health impacts, including vector-borne diseases such as dengue fever (DF), are major environmental and public health concerns in highly urbanized regions, especially in developing countries. It is necessary to explore the relationship between UVs and vector for effectively dealing with these problems. In this study, land-use types, including UVs, normal construction land (NCL), unused land (UL), vegetation, and water, were retrieved from the high-resolution remotely sensed imagery in the central area of Guangzhou in 2017. The vector density from May to October in 2017, including Aedes. albopictus (Ae. albopictus)'s Breteau index (BI), standard space index (SSI), and adult density index (ADI) were obtained from the vector surveillance system implemented by the Guangzhou Center for Disease Control and Prevention (CDC). Furthermore, the spatial and temporal patterns of vector monitoring sites and vector density were analyzed on a fine scale, and then the Geodetector tool was further employed to explore the relationships between vector density and land-use types. The monitoring sites were mainly located in NCL (55.70%-56.44%) and UV (13.14%-13.92%). Among the total monitoring sites of BI (79), SSI (312), and ADI (326), the random sites accounted for about 88.61%, 97.12%, and 98.47%, respectively. The density of Ae. albopictus was temporally related to rainfall and temperature and was obviously differentiated among different land-use types. Meanwhile, the grids with higher density, which were mostly concentrated in the Pearl River fork zone that collects a large number of UVs, showed that the density of Ae. albopictus was spatially associated with the UVs. Next, the results of the Geodetector illustrated that UVs posed great impact on the density of Ae. albopictus across the central region of Guangzhou. We suggest that the number of monitoring sites in the UVs should be appropriately increased to strengthen the current vector surveillance system in Guangzhou. This study will provide targeted guidance for local authorities, making more effective control and prevention measures on the DF epidemics.


Assuntos
Aedes/fisiologia , Distribuição Animal , Dengue/epidemiologia , Monitoramento Epidemiológico , Mosquitos Vetores/fisiologia , Aedes/crescimento & desenvolvimento , Animais , China/epidemiologia , Larva/fisiologia , Mosquitos Vetores/crescimento & desenvolvimento , Densidade Demográfica , Urbanização
9.
Parasit Vectors ; 12(1): 597, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31856896

RESUMO

BACKGROUND: In recent years, the Asian tiger mosquito Aedes albopictus has emerged as a species of major medical concern following its global expansion and involvement in many arbovirus outbreaks. On Réunion Island, Ae. albopictus was responsible for a large chikungunya outbreak in 2005-2006 and more recently an epidemic of dengue which began at the end of 2017 and is still ongoing at the time of writing. This dengue epidemic has seen a high number of human cases in south and west coastal regions, while few cases have been reported in the north and east of the island. To better understand the role of mosquito populations in such spatial patterns of dengue virus transmission in Réunion Island, we examined the genetic diversity and population structure of Ae. albopictus sampled across the island. RESULTS: Between November 2016 and March 2017, a total of 564 mosquitoes were collected from 19 locations in three main climatic regions (West, East and Center) of Réunion Island and were genotyped using 16 microsatellite loci. A high genetic diversity was observed with 2-15 alleles per locus and the average number of alleles per population varying between 4.70-5.90. Almost all FIS values were significantly positive and correlated to individual relatedness within populations using a hierarchical clustering approach based on principal components analyses (HCPC). However, the largest part of genetic variance was among individuals within populations (97%) while only 3% of genetic variance was observed among populations within regions. Therefore, no distinguishable population structure or isolation by distance was evidenced, suggesting high rates of gene flow at the island scale. CONCLUSIONS: Our results show high genetic diversity but no genetic structure of Ae. albopictus populations in Réunion Island thus reflecting frequent movements of mosquitoes between populations probably due to human activity. These data should help in the understanding of Ae. albopictus vector capacity and the design of effective mosquito control strategies.


Assuntos
Aedes/genética , Variação Genética , Mosquitos Vetores/genética , Aedes/classificação , Aedes/fisiologia , Animais , Febre de Chikungunya/transmissão , Dengue/transmissão , Genótipo , Humanos , Ilhas , Repetições de Microssatélites , Mosquitos Vetores/classificação , Mosquitos Vetores/fisiologia , Reunião
10.
PLoS One ; 14(12): e0226815, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31887129

RESUMO

Host seeking in the yellow fever mosquito, Aedes aegypti, and the African malaria mosquito, Anopheles coluzzii, relies on specific and generic host-derived odorants. Previous analyses indicate that the behavioral response of these species depends differentially on the presence of carbon dioxide (CO2) and other constituents in human breath for activation and attraction. In this study, we use a flight tube assay and electrophysiological analysis to assess the role of acetone, a major component of exhaled human breath, in modulating the behavioral and sensory neuronal response of these mosquito species, in the presence and absence of CO2. When presented alone at ecologically relevant concentrations, acetone increases attraction in Ae. aegypti, but not in An. coluzzii. Moreover, in combination with CO2, human breath-equivalents of acetone ranging between 0.1 and 10 ppm reproduces a behavioral response similar to that observed to human breath in host-seeking Ae. aegypti, but not in An. coluzzii. Acetone does, however, reduce attraction to CO2 in An. coluzzii, when presented at a higher concentration of 10 ppm. We identify the capitate peg A neuron of the maxillary palp of both species as a dual detector of CO2 and acetone. The sensory response to acetone, or binary blends of acetone and CO2, reflects the observed behavioral output in both Ae. aegypti and An. coluzzii. We conclude that host recognition is contextual and dependent on a combination of ecologically relevant odorants at naturally occurring concentrations that are encoded, in this case, by differences in the temporal structure of the neuronal response. This information should be considered when designing synthetic blends for that optimally attract mosquitoes for monitoring and control.


Assuntos
Acetona/farmacologia , Comportamento Animal/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Culicidae/fisiologia , Olfato , Aedes/fisiologia , Animais , Anopheles/fisiologia , Expiração , Comportamento de Busca por Hospedeiro/efeitos dos fármacos , Humanos , Malária/transmissão , Odorantes , Febre Amarela/transmissão
11.
Parasit Vectors ; 12(1): 584, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31842984

RESUMO

BACKGROUND: Blood meal host selection by mosquito vectors is an important component in understanding disease dynamics of pathogens that threaten endemic fauna in isolated islands such as Galápagos. Research on the feeding behavior of mosquitoes can provide clues to the hosts and vectors involved in disease transmission. This information is particularly critical for endemic wildlife fauna in island systems that have evolved without resistance to novel diseases such as avian malaria. The aims of this study were to determine the blood-feeding patterns of two species of mosquitoes found in Galápagos and discuss how their feeding behavior may influence the transmission of pathogens such as avian malaria. METHODS: In the summer of 2015, we sampled two mosquito species (Aedes taeniorhynchus and Culex quinquefasciatus) across 18 different sites on Isla Santa Cruz, which is the second largest island in Galápagos and has the largest human population. We trapped mosquitoes using CDC light traps and CDC gravid traps and identified sources of blood meals for engorged mosquitoes by sequencing a portion of the vertebrate mitochondrial cytochrome b gene. RESULTS: Out of 947 female mosquitoes captured, 320 were blood-fed, and PCR amplifications were successful for 301 of the blood meals. Results revealed that both Aedes taeniorhynchus and Culex quinquefasciatus feed from a variety of vertebrate taxa, numerically dominated by humans on Isla Santa Cruz. CONCLUSIONS: The high proportion of mammalian blood meals could represent locally available and abundant hosts on Santa Cruz. However, host surveys and estimates of relative abundances of vertebrate species will need to accompany mosquito trapping studies on non-inhabited and inhabited islands in Galápagos to further validate this.


Assuntos
Aedes/fisiologia , Culex/fisiologia , Comportamento Alimentar , Mosquitos Vetores/fisiologia , Animais , Citocromos b/genética , Equador , Entomologia/métodos , Enzimas/sangue , Enzimas/genética , Técnicas de Genotipagem/métodos , Humanos , Mamíferos
12.
Emerg Microbes Infect ; 8(1): 1668-1678, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31735122

RESUMO

Since its emergence in Yap Island in 2007, Zika virus (ZIKV) has affected all continents except Europe. Despite the hundreds of cases imported to European countries from ZIKV-infested regions, no local cases have been reported in localities where the ZIKV-competent mosquito Aedes albopictus is well established. Here we analysed the vector competence of European Aedes (aegypti and albopictus) mosquitoes to different genotypes of ZIKV. We demonstrate that Ae. albopictus from France was less susceptible to the Asian ZIKV than to the African ZIKV. Critically we show that effective crossing of anatomical barriers (midgut and salivary glands) after an infectious blood meal depends on a viral load threshold to trigger: (i) viral dissemination from the midgut to infect mosquito internal organs and (ii) viral transmission from the saliva to infect a vertebrate host. A viral load in body ≥4800 viral copies triggered dissemination and ≥12,000 viral copies set out transmission. Only 27.3% and 18.2% of Ae. albopictus Montpellier mosquitoes meet respectively these two criteria. Collectively, these compelling results stress the poor ability of Ae. albopictus to sustain a local transmission of ZIKV in Europe and provide a promising tool to evaluate the risk of ZIKV transmission in future outbreaks.


Assuntos
Aedes/fisiologia , Mosquitos Vetores/fisiologia , Infecção por Zika virus/transmissão , Zika virus/fisiologia , Aedes/genética , Aedes/virologia , Animais , Europa (Continente) , Feminino , Humanos , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , Carga Viral , Zika virus/genética , Infecção por Zika virus/virologia
13.
Emerg Microbes Infect ; 8(1): 1636-1641, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31711378

RESUMO

Yellow Fever (YF) remains a major public health issue in Sub-Saharan Africa and South America, despite the availability of an effective vaccine. In Africa, most YF outbreaks are reported in West Africa. However, urban outbreaks occurred in 2016 in both Angola and the Democratic Republic of Congo (DRC), and imported cases were reported in Chinese workers coming back from Africa. In Central Africa, Cameroon and the Republic of Congo host a high proportion of non-vaccinated populations increasing the risk of urban outbreaks. The main vector is Aedes aegypti and possibly, Aedes albopictus, both being anthropophilic and domestic mosquitoes. Here, we provide evidence that both Ae. aegypti and Ae. albopictus in Cameroon and the Republic of Congo are able to transmit Yellow fever virus (YFV) with higher rates of infection, dissemination, and transmission for Ae. aegypti. We conclude that the potential of both Aedes species to transmit YFV could increase the risk of urban YF transmission and urge public health authorities to intensify their efforts to control domestic vectors, and extend vaccine coverage to prevent major YFV outbreak.


Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Febre Amarela/transmissão , Vírus da Febre Amarela/fisiologia , Aedes/fisiologia , África Central , Animais , Feminino , Humanos , Mosquitos Vetores/fisiologia , Febre Amarela/virologia , Vírus da Febre Amarela/genética , Vírus da Febre Amarela/isolamento & purificação
14.
Parasit Vectors ; 12(1): 474, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31610804

RESUMO

BACKGROUND: The global spread of mosquito-borne diseases (MBD) has presented increasing challenges to public health. The transmission of MBD is mainly attributable to the biting behaviors of female mosquitoes. However, the ecological pattern of hourly host-seeking behavior in Aedes albopictus and its association with climatic variables are still not well understood, especially for a precise requirement for establishing an effective risk prediction system of MBD transmission. METHODS: Mosquito samples and data on mosquito hourly density and site-specific climatic variables, including temperature, relative humidity, illuminance and wind speed, were collected simultaneously in urban outdoor environments in Guangzhou during 2016-2018. Kernel regression models were used to assess the temporal patterns of hourly host-seeking behavior in mosquito populations, and negative binomial regression models in the Bayesian framework were used to investigate the associations of host-seeking behavior with climatic variables. RESULTS: Aedes albopictus was abundant, constituting 82% (5569/6790) of the total collected mosquitoes. Host-seeking behavior in Ae. albopictus varied across time and was significantly influenced by climatic variables. The predicted hourly mosquito densities showed non-linear relationships with temperature and illuminance, whereas density increased with relative humidity but generally decreased with wind speed. The range of temperature estimates for female biting was 16.4-37.1 °C, peaking at 26.5 °C (95% credible interval: 25.3-28.1). During the favorable periods, biting behavior of female Ae. albopictus was estimated to occur frequently all day long, presenting a bimodal distribution with peaks within 2-3 h around both dawn and dusk (05:00-08:00 h and 16:00-19:00 h). Moreover, a short-term association in hourly density between the females and males was found. CONCLUSIONS: Our field-based modeling study reveals that hourly host-seeking behavior of Ae. albopictus exhibits a complex pattern, with hourly variation constrained significantly by climatic variables. These findings lay a foundation for improving MBD risk assessments as well as practical strategies for vector control. For instances of all-day-long frequent female biting during the favorable periods in Guangzhou, effective integrated mosquito control measures must be taken throughout the day and night.


Assuntos
Aedes/fisiologia , Clima , Comportamento de Busca por Hospedeiro/fisiologia , Mosquitos Vetores/fisiologia , /prevenção & controle , Aedes/genética , Animais , Teorema de Bayes , Distribuição Binomial , China/epidemiologia , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Humanos , Umidade , Mordeduras e Picadas de Insetos/epidemiologia , Luz , Masculino , Mitocôndrias/enzimologia , Controle de Mosquitos , Mosquitos Vetores/genética , Reação em Cadeia da Polimerase , Densidade Demográfica , Chuva , Análise de Regressão , Estações do Ano , Temperatura , Fatores de Tempo , Vento
15.
Parasit Vectors ; 12(1): 477, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31610813

RESUMO

BACKGROUND: The Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse) is an important worldwide invasive species and can be a locally important vector of chikungunya, dengue and, potentially, Zika. This species is native to Southeast Asia where populations thrive in both temperate and tropical climates. A better understanding of the population structure of Ae. albopictus in Lao PDR is very important in order to support the implementation of strategies for diseases prevention and vector control. In the present study, we investigated the genetic variability of Ae. albopictus across a north-south transect in Lao PDR. METHODS: We used variability in a 1337-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), to assess the population structure of Ae. albopictus in Lao PDR. For context, we also examined variability at the same genetic locus in samples of Ae. albopictus from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA. RESULTS: We observed very high levels of genetic polymorphism with 46 novel haplotypes in Ae. albopictus from 9 localities in Lao PDR and Thailand populations. Significant differences were observed between the Luangnamtha population and other locations in Lao PDR. However, we found no evidence of isolation by distance. There was overall little genetic structure indicating ongoing and frequent gene flow among populations or a recent population expansion. Indeed, the neutrality test supported population expansion in Laotian Ae. albopictus and mismatch distribution analyses showed a lack of low frequency alleles, a pattern often seen in bottlenecked populations. When samples from Lao PDR were analyzed together with samples from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA, phylogenetic network and Bayesian cluster analysis showed that most populations from tropical/subtropical regions are more genetically related to each other, than populations from temperate regions. Similarly, most populations from temperate regions are more genetically related to each other, than those from tropical/subtropical regions. CONCLUSIONS: Aedes albopictus in Lao PDR are genetically related to populations from tropical/subtropical regions (i.e. Thailand, Singapore, and California and Texas in the USA). The extensive gene flow among locations in Lao PDR indicates that local control is undermined by repeated introductions from untreated sites.


Assuntos
Aedes/fisiologia , Mosquitos Vetores/fisiologia , Aedes/classificação , Aedes/genética , Aedes/virologia , Algoritmos , Animais , Ásia Sudeste , Teorema de Bayes , Análise por Conglomerados , DNA/química , DNA/isolamento & purificação , Complexo IV da Cadeia de Transporte de Elétrons/genética , Extremo Oriente , Feminino , Variação Genética , Genética Populacional , Haplótipos , Itália , Laos , Mitocôndrias/enzimologia , Controle de Mosquitos , Mosquitos Vetores/classificação , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , Filogenia , Análise de Sequência de DNA , Clima Tropical , Estados Unidos
16.
PLoS Negl Trop Dis ; 13(10): e0007806, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31618201

RESUMO

BACKGROUND: Aedes mosquitoes are vectors of arboviral diseases of great relevance for public health. The recent outbreaks of dengue, Zika, chikungunya and the rapid worldwide spreading of Aedes albopictus emphasize the need for improvement of vector surveillance and control. Host antibody response to mosquito salivary antigens is emerging as a relevant additional tool to directly assess vector-host contact, monitor efficacy of control interventions and evaluate risk of arboviral transmission. METHODOLOGY/PRINCIPAL FINDINGS: Groups of four BALB/c mice were immunized by exposure to bites of either Aedes albopictus or Aedes aegypti. The 34k2 salivary proteins from Ae. albopictus (al34k2) and Ae. aegypti (ae34k2) were expressed in recombinant form and Ae. albopictus salivary peptides were designed through B-cell epitopes prediction software. IgG responses to salivary gland extracts, peptides, al34k2 and ae34k2 were measured in exposed mice. Both al34k2 and ae34k2, with some individual and antigen-specific variation, elicited a clearly detectable antibody response in immunized mice. Remarkably, the two orthologous proteins showed very low level of immune cross-reactivity, suggesting they may eventually be developed as species-specific markers of host exposure. The al34k2 immunogenicity and the limited immune cross-reactivity to ae34k2 were confirmed in a single human donor hyperimmune to Ae. albopictus saliva. CONCLUSIONS/SIGNIFICANCE: Our study shows that exposure to bites of Ae. albopictus or Ae. aegypti evokes in mice species-specific IgG responses to al34k2 or ae34k2, respectively. Deeper understanding of duration of antibody response and validation in natural conditions of human exposure to Aedes mosquitoes are certainly needed. However, our findings point to the al34k2 salivary protein as a promising potential candidate for the development of immunoassays to evaluate human exposure to Ae. albopictus. This would be a step forward in the establishment of a serological toolbox for the simultaneous assessment of human exposure to Aedes vectors and the pathogens they transmit.


Assuntos
Aedes/imunologia , Imunoglobulina G/imunologia , Saliva/imunologia , Proteínas e Peptídeos Salivares/imunologia , Proteínas e Peptídeos Salivares/metabolismo , Aedes/fisiologia , Aedes/virologia , Animais , Formação de Anticorpos , Arbovirus/imunologia , Biomarcadores , Reações Cruzadas , Modelos Animais de Doenças , Feminino , Humanos , Imunização , Insetos Vetores , Camundongos , Camundongos Endogâmicos BALB C , Saliva/metabolismo , Glândulas Salivares/metabolismo , Proteínas e Peptídeos Salivares/genética , Especificidade da Espécie
17.
Parasit Vectors ; 12(1): 484, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31619269

RESUMO

BACKGROUND: Aedes vexans (Meigen) is considered a nuisance species in central Europe and the Mediterranean region. It is an anthropophilic and mammalophilic floodwater mosquito involved in the transmission of several arboviruses. Rift Valley fever (RVF) is a relevant mosquito-borne zoonosis, affecting mainly humans and ruminants, that causes severe impact in public health and economic loses. Due to globalization and climate change, the European continent is threatened by its introduction. The main purpose of the present study was to evaluate the vector competence of a European field-collected Ae. vexans population. METHODS: Aedes vexans field-collected larvae were reared in the laboratory under field-simulated conditions. To assess the vector competence for Rift Valley fever phlebovirus (RVFV) transmission, adult F0 females were exposed to infectious blood meals containing the 56/74 RVFV strain. Additionally, intrathoracic inoculations with the same virus strain were performed to evaluate the relevance of the salivary gland barriers. Natural circulation of alphavirus, flavivirus and phlebovirus was also tested. RESULTS: To our knowledge, an autochthonous Ae. vexans population was experimentally confirmed as a competent vector for RVFV for the first time. This virus was capable of infecting and disseminating within the studied Ae. vexans mosquitoes. Moreover, infectious virus was isolated from the saliva of disseminated specimens, showing their capacity to transmit the virus. Additionally, a natural infection with a circulating Mosquito flavivirus was detected. The co-infection with the Mosquito flavivirus seemed to modulate RVFV infection susceptibility in field-collected Ae. vexans, but further studies are needed to confirm its potential interference in RVFV transmission. CONCLUSIONS: Our results show that field-collected European Ae. vexans would be able to transmit RVFV in case of introduction into the continent. This should be taken into consideration in the design of surveillance and control programmes.


Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Febre do Vale de Rift/transmissão , Vírus da Febre do Vale do Rift/fisiologia , Zoonoses/transmissão , Aedes/citologia , Aedes/fisiologia , Alphavirus/isolamento & purificação , Animais , Bovinos , Linhagem Celular , Galinhas , Células Clonais , Europa (Continente) , Feminino , Flavivirus/isolamento & purificação , Inundações , Humanos , Mosquitos Vetores/fisiologia , Phlebovirus/isolamento & purificação , Chuva , Vírus da Febre do Vale do Rift/isolamento & purificação , Ruminantes , Saliva/virologia , Espanha , Organismos Livres de Patógenos Específicos , Células Vero , Água/parasitologia , Zoonoses/virologia
18.
Parasit Vectors ; 12(1): 494, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31640810

RESUMO

BACKGROUND: Epidemics of dengue, chikungunya and Zika are a growing threat to areas where Aedes aegypti are present. The efficacy of chemical control of Ae. aegypti is threatened by the increasing frequency of insecticide resistance. The objective of this study was to determine the susceptibility status as well as the biochemical and molecular mechanisms underlying insecticide resistance in three populations of Ae. aegypti in high risk areas of dengue, chikungunya, and Zika in Peru. METHODS: Bioassays were conducted on adult Ae. aegypti to evaluate their susceptibility to insecticides used currently or historically for mosquito control in Peru, including six pyrethroids, three organophosphates and one organochlorine, in populations of Ae. aegypti from the districts of Chosica (Department of Lima), Punchana (Department of Loreto) and Piura (Department of Piura). Resistance mechanisms were determined by biochemical assays to assess activity levels of key detoxification enzyme groups (nonspecific esterases, multi-function oxidases, glutathione S-transferases and insensitive acetylcholinesterase). Real-time PCR assays were used to detect two kdr mutations (V1016I and F1534C) on the voltage-gated sodium channel gene. RESULTS: Resistance to DDT was detected in all three populations, and resistance to pyrethroids was detected in all populations except the population from Chosica, which still exhibited susceptibility to deltamethrin. Resistance to organophosphates was also detected, with the exception of populations from Punchana and Piura, which still demonstrated susceptibility to malathion. In general, no increase or alteration of activity of any enzyme group was detected. Both 1016I and 1534C alleles were detected in Punchana and Piura, while only the 1534C allele was detected in Chosica. CONCLUSIONS: The results suggest that resistance to multiple classes of insecticides exist in areas important to Ae. aegypti-borne disease transmission in Peru. The F1534C mutation was present in all 3 populations and the V1016I mutation was present in 2 populations. To our knowledge, this is the first report of the presence of 1016I and 1534C in Ae. aegypti in Peru. The absence of highly elevated enzymatic activity suggests that target site resistance is a key mechanism underlying insecticide resistance in these populations, although further research is needed to fully understand the role of metabolic resistance mechanisms in these populations.


Assuntos
Aedes/fisiologia , Resistência a Inseticidas/fisiologia , Inseticidas/farmacologia , Mosquitos Vetores/fisiologia , Aedes/efeitos dos fármacos , Animais , Bioensaio , DDT/farmacologia , Malation/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Nitrilos/farmacologia , Organofosfatos/farmacologia , Peru , Piretrinas/farmacologia
19.
PLoS Negl Trop Dis ; 13(10): e0007771, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31658265

RESUMO

BACKGROUND: Important arboviral diseases, such as dengue, chikungunya, and Zika virus infections, are transmitted mainly by the Aedes aegypti vector. So far, controlling this vector species with current tools and strategies has not demonstrated sustainable and significant impacts. Our main objective was to evaluate whether open field release of sterile males, produced from combining the sterile insect technique using radiation with the insect incompatible technique through Wolbachia-induced incompatibility (SIT/IIT), could suppress natural populations of Ae. aegypti in semi-rural village settings in Thailand. METHODOLOGY/PRINCIPAL FINDINGS: Irradiated Wolbachia-infected Aedes aegypti males produced by the SIT/IIT approach were completely sterile and were able to compete with the wild fertile ones. Open field release of these sterile males was conducted in an ecologically isolated village in Chachoengsao Province, eastern Thailand. House-to-house visit and media reports resulted in community acceptance and public awareness of the technology. During intervention, approximately 100-200 sterile males were released weekly in each household. After 6 months of sterile male release, a significant reduction (p<0.05) of the mean egg hatch rate (84%) and the mean number of females per household (97.30%) was achieved in the treatment areas when compared to the control ones. CONCLUSIONS/SIGNIFICANCE: Our study represents the first open field release of sterile Ae. aegypti males developed from a combined SIT/IIT approach. Entomological assessment using ovitraps, adult sticky traps, and portable vacuum aspirators confirmed the success in reducing natural populations of Ae. aegypti females in treated areas. Public awareness through media resulted in positive support for practical use of this strategy in wider areas. Further study using a systematic randomized trial is needed to determine whether this approach could have a significant impact on the diseases transmitted by Ae. aegypti vector.


Assuntos
Aedes/fisiologia , Entomologia/métodos , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , População Rural , Aedes/microbiologia , Aedes/efeitos da radiação , Animais , Feminino , Humanos , Infertilidade Masculina , Masculino , Mosquitos Vetores/microbiologia , Mosquitos Vetores/efeitos da radiação , Dinâmica Populacional , Caracteres Sexuais , Tailândia , Wolbachia/genética , Wolbachia/fisiologia
20.
Infect Dis Poverty ; 8(1): 71, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31477185

RESUMO

BACKGROUND: Dengue is a global disease, transmitted by the Aedes vectors. In 2018, there were 80 615 dengue cases with 147 deaths in Malaysia. Currently, the nationwide surveillance programs are dependent on Aedes larval surveys and notifications of lab-confirmed human infections. The existing, reactive programs appear to lack sensitivity and proactivity. More efficient dengue vector surveillance/control methods are needed. METHODS: A parallel, cluster, randomized controlled, interventional trial is being conducted for 18 months in Damansara Damai, Selangor, Malaysia, to determine the efficacy of using gravid oviposition sticky (GOS) trap and dengue non-structural 1 (NS1) antigen test for early surveillance of dengue among Aedes mosquitoes to reduce dengue outbreaks. Eight residential apartments were randomly assigned into intervention and control arms. GOS traps are set at the apartments to collect Aedes weekly, following which dengue NS1 antigen is detected in these mosquitoes. When a dengue-positive mosquito is detected, the community will be advised to execute vector search-and-destroy and protective measures. The primary outcome concerns the the percentage change in the (i) number of dengue cases and (ii) durations of dengue outbreaks. Whereas other outcome measures include the change in density threshold of Aedes and changes in dengue-related knowledge, attitude and practice among cluster inhabitants. DISCUSSION: This is a proactive and early dengue surveillance in the mosquito vector that does not rely on notification of dengue cases. Surveillance using the GOS traps should be able to efficiently provide sufficient coverage for multistorey dwellings where population per unit area is likely to be higher. Furthermore, trapping dengue-infected mosquitoes using the GOS trap, helps to halt the dengue transmission carried by the mosquito. It is envisaged that the results of this randomized controlled trial will provide a new proactive, cheap and targeted surveillance tool for the prevention and control of dengue outbreaks. TRIAL REGISTRATION: This is a parallel-cluster, randomized controlled, interventional trial, registered at ClinicalTrials.gov (ID: NCT03799237), on 8th January 2019 (retrospectively registered).


Assuntos
Aedes/fisiologia , Aedes/virologia , Antígenos Virais/análise , Vírus da Dengue/isolamento & purificação , Oviposição , Proteínas não Estruturais Virais/análise , Animais , Vigilância da População , Ensaios Clínicos Controlados Aleatórios como Assunto
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