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1.
Virol J ; 17(1): 9, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31973727

RESUMO

Yellow fever (YF) is an acute viral disease, affecting humans and non-human primates (NHP), caused by the yellow fever virus (YFV). Despite the existence of a safe vaccine, YF continues to cause morbidity and mortality in thousands of people in Africa and South America. Since 2016, massive YF outbreaks have taken place in Brazil, reaching YF-free zones, causing thousands of deaths of humans and NHP. Here we reviewed the main epidemiological aspects, new clinical findings in humans, and issues regarding YFV infection in vectors and NHP in Brazil. The 2016-2019 YF epidemics have been considered the most significant outbreaks of the last 70 years in the country, and the number of human cases was 2.8 times higher than total cases in the previous 36 years. A new YFV lineage was associated with the recent outbreaks, with persistent circulation in Southeast Brazil until 2019. Due to the high number of infected patients, it was possible to evaluate severity and death predictors and new clinical features of YF. Haemagogus janthinomys and Haemagogus leucocelaenus were considered the primary vectors during the outbreaks, and no human case suggested the occurrence of the urban transmission cycle. YFV was detected in a variety of NHP specimens presenting viscerotropic disease, similar to that described experimentally. Further studies regarding NHP sensitivity to YFV, YF pathogenesis, and the duration of the immune response in NHP could contribute to YF surveillance, control, and future strategies for NHP conservation.

2.
Rev Soc Bras Med Trop ; 53: e20190222, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31859948

RESUMO

INTRODUCTION: The genus Haemagogus Williston is restricted to Central America and North and middle of South America and it includes numerous species of yellow fever virus vectors. METHODS: Adult female and larvae mosquitoes were collected using hand aspirators and dipper and pipette, respectively. RESULTS: The first record of a species of Haemagogus and particularly of Haemagogus spegazzinii was from La Pampa, Argentina. With this registry, the number of species found in La Pampa province rises to 18. CONCLUSIONS: New information on breeding sites for the species and implications of this new record suggest a possible extension of distribution in the near future.


Assuntos
Culicidae/classificação , Mosquitos Vetores/classificação , Animais , Argentina , Feminino , Febre Amarela/transmissão
3.
Gates Open Res ; 3: 1547, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31667465

RESUMO

Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown in laboratory studies to reduce transmission of a range of viruses including dengue, Zika, chikungunya, yellow fever, and Mayaro viruses that cause human disease. Here we report the entomological and epidemiological outcomes of staged deployment of Wolbachia across nearly all significant dengue transmission risk areas in Australia. Methods: The  wMel strain of  Wolbachia was backcrossed into the local  Aedes aegypti genotype (Cairns and Townsville backgrounds) and mosquitoes were released in the field by staff or via community assisted methods. Mosquito monitoring was undertaken and mosquitoes were screened for the presence of  Wolbachia. Dengue case notifications were used to track dengue incidence in each location before and after releases. Results: Empirical analyses of the Wolbachia mosquito releases, including data on the density, frequency and duration of Wolbachia mosquito releases, indicate that Wolbachia can be readily established in local mosquito populations, using a variety of deployment options and over short release durations (mean release period 11 weeks, range 2-22 weeks). Importantly, Wolbachia frequencies have remained stable in mosquito populations since releases for up to 8 years. Analysis of dengue case notifications data demonstrates near-elimination of local dengue transmission for the past five years in locations where Wolbachia has been established. The regression model estimate of Wolbachia intervention effect from interrupted time series analyses of case notifications data prior to and after releases, indicated a 96% reduction in dengue incidence in Wolbachia treated populations (95% confidence interval: 84 - 99%). Conclusion: Deployment of the wMel strain of Wolbachia into local Ae. aegypti populations across the Australian regional cities of Cairns and most smaller regional communities with a past history of dengue has resulted in the reduction of local dengue transmission across all deployment areas.

4.
Proc Biol Sci ; 286(1914): 20192136, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31690238

RESUMO

Interactions between Aedes (Stegomyia) species and non-human primate (NHP) and human hosts govern the transmission of the pathogens, dengue, zika, yellow fever and chikungunya viruses. Little is known about Aedes mosquito olfactory interactions with these hosts in the domestic and sylvatic cycles where these viruses circulate. Here, we explore how the different host-derived skin odours influence Aedes mosquito responses in these two environments. In field assays, we show that the cyclic ketone cyclohexanone is a signature cue for Aedes mosquitoes to detect the NHP baboon, sykes and vervet, whereas for humans, it is the unsaturated aliphatic keto-analogue 6-methyl-5-hepten-2-one (sulcatone). We find that in the sylvatic environment, CO2-baited traps combined with either cyclohexanone or sulcatone increased trap catches of Aedes mosquitoes compared to traps either baited with CO2 alone or CO2 combined with NHP- or human-derived crude skin odours. In the domestic environment, each of these odourants and crude human skin odours increased Aedes aegypti catches in CO2-baited traps. These results expand our knowledge on the role of host odours in the ecologies of Aedes mosquitoes, and the likelihood of associated spread of pathogens between primates and humans. Both cyclohexanone and sulcatone have potential practical applications as lures for monitoring Aedes disease vectors.

5.
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.

6.
PeerJ ; 7: e7920, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31745446

RESUMO

Background: Zika is of great medical relevance due to its rapid geographical spread in 2015 and 2016 in South America and its serious implications, for example, certain birth defects. Recent epidemics urgently require a better understanding of geographic patterns of the Zika virus transmission risk. This study aims to map the Zika virus transmission risk in South and Central America. We applied the maximum entropy approach, which is common for species distribution modelling, but is now also widely in use for estimating the geographical distribution of infectious diseases. Methods: As predictor variables we used a set of variables considered to be potential drivers of both direct and indirect effects on the emergence of Zika. Specifically, we considered (a) the modelled habitat suitability for the two main vector species Aedes aegypti and Ae. albopictus as a proxy of vector species distributions; (b) temperature, as it has a great influence on virus transmission; (c) commonly called evidence consensus maps (ECM) of human Zika virus infections on a regional scale as a proxy for virus distribution; (d) ECM of human dengue virus infections and, (e) as possibly relevant socio-economic factors, population density and the gross domestic product. Results: The highest values for the Zika transmission risk were modelled for the eastern coast of Brazil as well as in Central America, moderate values for the Amazon basin and low values for southern parts of South America. The following countries were modelled to be particularly affected: Brazil, Colombia, Cuba, Dominican Republic, El Salvador, Guatemala, Haiti, Honduras, Jamaica, Mexico, Puerto Rico and Venezuela. While modelled vector habitat suitability as predictor variable showed the highest contribution to the transmission risk model, temperature of the warmest quarter contributed only comparatively little. Areas with optimal temperature conditions for virus transmission overlapped only little with areas of suitable habitat conditions for the two main vector species. Instead, areas with the highest transmission risk were characterised as areas with temperatures below the optimum of the virus, but high habitat suitability modelled for the two main vector species. Conclusion: Modelling approaches can help estimating the spatial and temporal dynamics of a disease. We focused on the key drivers relevant in the Zika transmission cycle (vector, pathogen, and hosts) and integrated each single component into the model. Despite the uncertainties generally associated with modelling, the approach applied in this study can be used as a tool and assist decision making and managing the spread of Zika.

7.
PLoS Negl Trop Dis ; 13(10): e0007783, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31589616

RESUMO

The case-fatality rate of yellow fever virus (YFV) is one of the highest among arthropod-borne viruses (arboviruses). Although historically, the Asia-Pacific region has remained free of YFV, the risk of introduction has never been higher due to the increasing influx of people from endemic regions and the recent outbreaks in Africa and South America. Singapore is a global hub for trade and tourism and therefore at high risk for YFV introduction. Effective control of the main domestic mosquito vector Aedes aegypti in Singapore has failed to prevent re-emergence of dengue, chikungunya and Zika viruses in the last two decades, raising suspicions that peridomestic mosquito species untargeted by domestic vector control measures may contribute to arbovirus transmission. Here, we provide empirical evidence that the peridomestic mosquito Aedes malayensis found in Singapore can transmit YFV. Our laboratory mosquito colony recently derived from wild Ae. malayensis in Singapore was experimentally competent for YFV to a similar level as Ae. aegypti controls. In addition, we captured Ae. malayensis females in one human-baited trap during three days of collection, providing preliminary evidence that host-vector contact may occur in field conditions. Finally, we detected Ae. malayensis eggs in traps deployed in high-rise building areas of Singapore. We conclude that Ae. malayensis is a competent vector of YFV and re-emphasize that vector control methods should be extended to target peridomestic vector species.

8.
PLoS Comput Biol ; 15(9): e1007355, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31545790

RESUMO

Yellow fever is a vector-borne disease endemic in tropical regions of Africa, where 90% of the global burden occurs, and Latin America. It is notoriously under-reported with uncertainty arising from a complex transmission cycle including a sylvatic reservoir and non-specific symptom set. Resulting estimates of burden, particularly in Africa, are highly uncertain. We examine two established models of yellow fever transmission within a Bayesian model averaging framework in order to assess the relative evidence for each model's assumptions and to highlight possible data gaps. Our models assume contrasting scenarios of the yellow fever transmission cycle in Africa. The first takes the force of infection in each province to be static across the observation period; this is synonymous with a constant infection pressure from the sylvatic reservoir. The second model assumes the majority of transmission results from the urban cycle; in this case, the force of infection is dynamic and defined through a fixed value of R0 in each province. Both models are coupled to a generalised linear model of yellow fever occurrence which uses environmental covariates to allow us to estimate transmission intensity in areas where data is sparse. We compare these contrasting descriptions of transmission through a Bayesian framework and trans-dimensional Markov chain Monte Carlo sampling in order to assess each model's evidence given the range of uncertainty in parameter values. The resulting estimates allow us to produce Bayesian model averaged predictions of yellow fever burden across the African endemic region. We find strong support for the static force of infection model which suggests a higher proportion of yellow fever transmission occurs as a result of infection from an external source such as the sylvatic reservoir. However, the model comparison highlights key data gaps in serological surveys across the African endemic region. As such, conclusions concerning the most prevalent transmission routes for yellow fever will be limited by the sparsity of data which is particularly evident in the areas with highest predicted transmission intensity. Our model and estimation approach provides a robust framework for model comparison and predicting yellow fever burden in Africa. However, key data gaps increase uncertainty surrounding estimates of model parameters and evidence. As more mathematical models are developed to address new research questions, it is increasingly important to compare them with established modelling approaches to highlight uncertainty in structures and data.


Assuntos
Modelos Biológicos , Febre Amarela/transmissão , Aedes/virologia , África , Animais , Teorema de Bayes , Biologia Computacional , Humanos , Modelos Estatísticos , Febre Amarela/epidemiologia , Vírus da Febre Amarela
9.
Int J Infect Dis ; 87: 143-150, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31382047

RESUMO

OBJECTIVES: Yellow fever virus historically was a frequent threat to American and European coasts. Medical milestones such as the discovery of mosquitoes as vectors and subsequently an effective vaccine significantly reduced its incidence, in spite of which, thousands of cases of this deathly disease still occur regularly in Sub-Saharan Africa and the Amazonian basin in South America, which are usually not reported. An urban outbreak in Angola, consecutive years of increasing incidence near major Brazilian cities, and imported cases in China, South America and Europe, have brought this virus back to the global spotlight. The aim of this article is to underline that the preventive YFV measures, such as vaccination, need to be carefully revised in order to minimize the risks of new YFV outbreaks, especially in urban or immunologically vulnerable places. Furthermore, this article highlights the diverse factors that have favored the spread of other Aedes spp.-associated arboviral diseases like Dengue, Chikungunya and Zika, to northern latitudes causing epidemics in the United States and Europe, emphasizing the possibility that YFV might follow the path of these viruses unless enhanced surveillance and efficient control systems are urgently initiated.


Assuntos
Febre Amarela/epidemiologia , Vírus da Febre Amarela/isolamento & purificação , Animais , Humanos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , América do Norte/epidemiologia , Febre Amarela/transmissão , Febre Amarela/virologia , Vírus da Febre Amarela/classificação , Vírus da Febre Amarela/genética
11.
Insect Biochem Mol Biol ; 111: 103169, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31103782

RESUMO

The yellow fever mosquito, Aedes aegypti, serves as the primary vector for epidemic transmission of yellow fever, dengue, Zika (ZIKV), and chikungunya viruses to humans. Control of Ae. aegypti is currently limited to insecticide applications and larval habitat management; however, to combat growing challenges with insecticide resistance, novel genetic approaches for vector population reduction or transmission interruption are being aggressively pursued. The objectives of this study were to assess the ability of the Ae. aegypti antiviral exogenous-small interfering RNA (exo-siRNA) response to inhibit ZIKV infection and transmission, and to identify the optimal RNA interference (RNAi) target region in the ZIKV genome. We accomplished these objectives by in vitro transcription of five long double-stranded RNAs (dsRNAs) from the genome region spanning the NS2B-NS3-NS4A genes, which were the most highly conserved among ZIKV RNA sequences representing both East and West African and Asian-American clades, and evaluation of the ability of these dsRNAs to trigger an effective antiviral exo-siRNA response after intrathoracic injection into Ae. aegypti. In a pilot study, five ZIKV dsRNAs were tested by intrathoracic inoculation of 250 ng dsRNA into groups of approximately 5-day-old mosquitoes. Three days post-inoculation, mosquitoes were provided an infectious blood-meal containing ZIKV strain PRVABC59 (Puerto Rico), MR766 (Uganda), or 41525 (Senegal). On days 7 and 14 post-infection individual whole mosquito bodies were assessed for ZIKV infectious titer by plaque assays. Based on the results of this initial assessment, three dsRNAs were selected for further evaluation of viral loads of matched body and saliva expectorants using a standardized infectious dose of 1 × 107 PFU/mL of each ZIKV strain. Fourteen days post-exposure to ZIKV, paired saliva and carcass samples were harvested from individual mosquitoes and assessed for ZIKV RNA load by qRT-PCR. Injection of each of the three dsRNAs resulted in significant inhibition of replication of all three strains of ZIKV in mosquito bodies and saliva. This study lays critical groundwork for pursuing ZIKV transmission-blocking strategies that exploit the Ae. aegypti exo-siRNA response for arbovirus suppression in natural populations.


Assuntos
Aedes/virologia , Interferência de RNA , Infecção por Zika virus/transmissão , Zika virus/genética , Animais , Bovinos , Mosquitos Vetores/virologia , Projetos Piloto , RNA de Cadeia Dupla , RNA Interferente Pequeno , Saliva/virologia , Análise de Sequência de RNA , Células Vero , Carga Viral , Replicação Viral , Zika virus/fisiologia , Infecção por Zika virus/virologia
12.
Mem Inst Oswaldo Cruz ; 114: e190076, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31038550

RESUMO

BACKGROUND: In Brazil, the Yellow Fever virus (YFV) is endemic in the Amazon, from where it eventually expands into epidemic waves. Coastal south-eastern (SE) Brazil, which has been a YFV-free region for eight decades, has reported a severe sylvatic outbreak since 2016. The virus spread from the north toward the south of the Rio de Janeiro (RJ) state, causing 307 human cases with 105 deaths during the 2016-2017 and 2017-2018 transmission seasons. It is unclear, however, whether the YFV would persist in the coastal Atlantic Forest of RJ during subsequent transmission seasons. OBJECTIVES: To conduct a real-time surveillance and assess the potential persistence of YFV in the coastal Atlantic Forest of RJ during the 2018-2019 transmission season. METHODS: We combined epizootic surveillance with fast diagnostic and molecular, phylogenetic, and evolutionary analyses. FINDINGS: Using this integrative strategy, we detected the first evidence of YFV re-emergence in the third transmission season (2018-2019) in a dying howler monkey from the central region of the RJ state. The YFV detected in 2019 has the molecular signature associated with the current SE YFV outbreak and exhibited a close phylogenetic relationship with the YFV lineage that circulated in the same Atlantic Forest fragment during the past seasons. This lineage circulated along the coastal side of the Serra do Mar mountain chain, and its evolution seems to be mainly driven by genetic drift. The potential bridge vector Aedes albopictus was found probing on the recently dead howler monkey in the forest edge, very close to urban areas. MAIN CONCLUSIONS: Collectively, our data revealed that YFV transmission persisted at the same Atlantic Forest area for at least three consecutive transmission seasons without the need of new introductions. Our real-time surveillance strategy permitted health authorities to take preventive actions within 48 h after the detection of the sick non-human primate. The local virus persistence and the proximity of the epizootic forest to urban areas reinforces the concern with regards to the risk of re-urbanisation and seasonal re-emergence of YFV, stressing the need for continuous effective surveillance and high vaccination coverage in the SE region, particularly in RJ, an important tourist location.


Assuntos
Aedes/virologia , Febre Amarela/epidemiologia , Febre Amarela/virologia , Vírus da Febre Amarela/genética , Alouatta , Animais , Brasil/epidemiologia , Surtos de Doenças , Humanos , Filogeografia , Estações do Ano , População Urbana , Febre Amarela/transmissão
13.
Artigo em Espanhol | PAHO-IRIS | ID: phr-50939

RESUMO

[RESUMEN]. El aumento en la incidencia y distribución geográfica de las arbovirosis constituye uno de los principales problemas de salud pública en la Región de las Américas. La incidencia del dengue ha experimentado una tendencia creciente en los últimos decenios en la Región, donde se ha pasado de una endemicidad baja a hiperendemicidad. También, la incidencia de la fiebre amarilla se ha intensificado en este período, y ha pasado de una actividad restringida a zonas selváticas a presentar brotes urbanos. El chikunguña comenzó a propagarse de forma pandémica en el 2005 a un ritmo sin precedentes y llegó al continente americano en el 2013. Al año siguiente, la infección por el virus del Zika irrumpió también en la Región con un brote explosivo acompañado de gravísimas anomalías congénitas y trastornos neurológicos, hasta convertirse en una de las mayores crisis de salud en los últimos años. La inadecuada vigilancia de las arbovirosis en la Región y la carencia de pruebas serológicas para diferenciar entre los distintos virus plantean retos considerables. Sigue habiendo pocas evidencias científicas en respaldo de las intervenciones de control de vectores. El manejo clínico sigue siendo la piedra angular del control de estas enfermedades. En la actualidad, solo están autorizadas en la Región de las Américas las vacunas contra la fiebre amarilla y contra el dengue, si bien hay varias vacunas experimentales en fase de investigación en ensayos clínicos. El Grupo Mundial de Expertos en Arbovirus ofrece en este artículo un panorama de los progresos, los retos y las recomendaciones sobre prevención y control de las arbovirosis en los países de la Región de las Américas.


[ABSTRACT]. The increasing geographical spread and disease incidence of arboviral infections are among the greatest public health concerns in the Americas. The region has observed an increasing trend in dengue incidence in the last decades, evolving from low to hyperendemicity. Yellow fever incidence has also intensified in this period, expanding from sylvatic-restricted activity to urban outbreaks. Chikungunya started spreading pandemically in 2005 at an unprecedented pace, reaching the Americas in 2013. The following year, Zika also emerged in the region with an explosive outbreak, carrying devastating congenital abnormalities and neurologic disorders and becoming one of the greatest global health crises in years. The inadequate arbovirus surveillance in the region and the lack of serologic tests to differentiate among viruses poses substantial challenges. The evidence for vector control interventions remains weak. Clinical management remains the mainstay of arboviral disease control. Currently, only yellow fever and dengue vaccines are licensed in the Americas, with several candidate vaccines in clinical trials. The Global Arbovirus Group of Experts provides in this article an overview of progress, challenges, and recommendations on arboviral prevention and control for countries of the Americas.


Assuntos
Infecções por Arbovirus , Aedes , Dengue , Febre Amarela , Vírus Chikungunya , Zika virus , Doenças Transmissíveis , Américas , Infecções por Arbovirus , Febre Amarela , Vírus Chikungunya , Zika virus , Doenças Transmissíveis
14.
CES med ; 33(1): 42-50, ene.-abr. 2019.
Artigo em Espanhol | LILACS-Express | ID: biblio-1039330

RESUMO

Resumen En esta revisión se aborda a Aedes, el género de insectos más relevante en relación a la transmisión de agentes patógenos virales entre los que se cuentan dengue, zika, chikungunya, fiebre amarilla, entre otros. Este vector posee una rápida tasa de desarrollo y alta supervivencia, las cuales puede variar en respuesta a muchos factores bióticos y abióticos del ambiente. Entre estos últimos está la temperatura, la cual puede ejercer una considerable influencia en la capacidad vectorial, ya que impacta en la dinámica de la población del mosquito, la cinética del ciclo biológico, la respuesta inmunológica frente al virus del dengue, entre otros aspectos. Este conocimiento puede resultar útil en la realización de mejores proyecciones de los efectos del cambio climático sobre la incidencia del dengue, así como lograr una detección temprana de posibles brotes epidémicos que permitan la planeación oportuna de una respuesta rápida y eficaz para lograr la reducción y el control de la enfermedad.


Abstract This review presents Aedes, the most relevant insect genus in relation to the transmission of viral pathogens: dengue, zika, chikungunya, yellow fever, among others. This vector has a rapid rate of development and high survival, which might vary in response to many biotic and abiotic factors of environment. Among the latter is the temperature, which can exert a considerable influence on vectorial capacity, since it affects the dynamics of the mosquito population, the kinetics of the biological cycle, the immune response against the dengue virus, among other aspects. This knowledge can be useful in achieving better projections of the effects of climate change on the incidence of dengue, as well as achieving early detection of possible epidemic outbreaks that allow the timely planning of a rapid and effective response to achieve the reduction and control of the disease.

15.
Nat Ecol Evol ; 3(4): 561-569, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30886369

RESUMO

Zika virus (ZIKV), discovered in the Zika Forest of Uganda in 1947, is a mosquito-borne flavivirus related to yellow fever, dengue and West Nile viruses. From its discovery until 2007, only sporadic ZIKV cases were reported, with mild clinical manifestations in patients. Therefore, little attention was given to this virus before epidemics in the South Pacific and the Americas that began in 2013. Despite a growing number of ZIKV studies in the past three years, many aspects of the virus remain poorly characterized, particularly the spectrum of species involved in its transmission cycles. Here, we review the mosquito and vertebrate host species potentially involved in ZIKV vector-borne transmission worldwide. We also provide an evidence-supported analysis regarding the possibility of ZIKV spillback from an urban cycle to a zoonotic cycle outside Africa, and we review hypotheses regarding recent emergence and evolution of ZIKV. Finally, we identify critical remaining gaps in the current knowledge of ZIKV vector-borne transmission.


Assuntos
Mosquitos Vetores/fisiologia , Infecção por Zika virus/transmissão , Zika virus/fisiologia , Animais , Culicidae , Evolução Molecular , Humanos
16.
Environ Res ; 172: 693-699, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30884421

RESUMO

BACKGROUND: Climate change allows Aedes aegypti to infest new areas. Consequently, it enables the arboviruses the mosquito transmits -- e.g., dengue, chikungunya, Zika and yellow fever - to emerge in previously uninfected areas. An example is the Portuguese island of Madeira during 2012-13. OBJECTIVE: We aim to understand how climate change will affect the future spread of this potent vector, as an aid in assessing the risk of disease outbreaks and effectively allocating resources for vector control. METHODS: We used an empirically-informed, process-based mathematical model to study the feasibility of Aedes aegypti infestation into continental Europe. Based on established global climate-change scenario data, we assess the potential of Aedes aegypti to establish in Europe over the 21st century by estimating the vector population growth rate for five climate models (GCM5). RESULTS: In a low carbon emission future (RCP2.6), we find minimal change to the current situation throughout the whole of the 21st century. In a high carbon future (RCP8.5), a large parts of southern Europe risks being invaded by Aedes aegypti. CONCLUSION: Our results show that successfully enforcing the Paris Agreement by limiting global warming to below 2 °C significantly lowers the risk for infestation of Aedes aegypti and consequently of potential large-scale arboviral disease outbreaks in Europe within the 21st century.


Assuntos
Aedes , Mudança Climática , Mosquitos Vetores , Aedes/fisiologia , Aedes/virologia , Animais , Cidades , Europa (Continente)/epidemiologia , Modelos Teóricos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Viroses/epidemiologia , Viroses/transmissão
17.
Viruses ; 11(2)2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30759739

RESUMO

Mosquito-borne diseases constitute a large portion of infectious diseases, causing more than 700,000 deaths annually. Mosquito-transmitted viruses, such as yellow fever, dengue, West Nile, chikungunya, and Zika viruses, have re-emerged recently and remain a public health threat worldwide. Global climate change, rapid urbanization, burgeoning international travel, expansion of mosquito populations, vector competence, and host and viral genetics may all together contribute to the re-emergence of arboviruses. In this brief review, we summarize the host and viral genetic determinants that may enhance infectivity in the host, viral fitness in mosquitoes and viral transmission by mosquitoes.


Assuntos
Infecções por Arbovirus/transmissão , Arbovirus/genética , Evolução Molecular , Interações entre Hospedeiro e Microrganismos/genética , Mosquitos Vetores/virologia , Animais , Febre de Chikungunya/transmissão , Doenças Transmissíveis Emergentes/virologia , Dengue/transmissão , Aptidão Genética , Humanos , Camundongos , Saúde Pública , Febre Amarela/transmissão
18.
Acta Trop ; 192: 129-137, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30763563

RESUMO

The yellow fever mosquito, Aedes aegypti, has facilitated the re-emergence of dengue virus (DENV) and emergence of chikungunya virus (CHIKV) and Zika virus (ZIKV) in the Americas and the Caribbean. The recent transmission of these arboviruses in the continental United States has been limited, to date, to South Florida and South Texas despite Ae. aegypti occurring over a much larger geographical region within the country. The main goal of our study was to provide the first long term longitudinal study of Ae. aegypti and enhance the knowledge about the indoor and outdoor relative abundance of Ae. aegypti as a proxy for mosquito-human contact in South Texas, a region of the United States that is at high risk for mosquito-borne virus transmission. Here, the relative abundance of indoors and outdoors mosquitoes of households in eight different communities was described. Surveillance was done weekly from September 2016 to April 2018 using the CDC Autocidal Gravid Ovitraps in low- and middle-income communities. A total of 69 houses were included in this survey among which 36 were in the low-income communities (n = 11 for Donna, n = 15 for Progresso, n = 5 for Mesquite, n = 5 for Chapa) and 33 in middle-income communities (n = 9 for La Feria, n = 8 for Weslaco, n = 11 for McAllen, and n = 5 for Rio Rico). Overall, Ae. aegypti was the dominant species (59.2% of collections, n = 7255) followed by Culex spp. mosquitoes (27.3% of collections, n = 3350). Furthermore, we demonstrated for Ae. aegypti that 1) outdoor relative abundance was higher compared to indoor relative abundance, 2) low-income communities were associated with an increase in mosquito relative abundance indoors when compared to middle-income communities, 3) no difference was observed in the number of mosquitoes collected outdoors between low-income and middle-income communities, and 4) warmer months were positively correlated with outdoor relative abundance whereas no seasonality was observed in the relative abundance of mosquitoes indoors. Additionally, Ae. aegypti mosquitoes collected in South Texas were tested using a specific ZIKV/CHIKV multiplex real-time PCR assay, however, none of the mosquitoes tested positive. Our data highlights the occurrence of mosquitoes indoors in the continental United States and that adults are collected nearly every week of the calendar year. These mosquito data, obtained concurrently with local ZIKV transmission of 10 locally acquired cases in nearby communities, represent a baseline for future studies in the Lower Rio Grande Valley (LRGV) including vector control interventions relying on the oviposition behavior to reduce mosquito populations and pathogen transmission.


Assuntos
Aedes/virologia , Febre de Chikungunya/transmissão , Culex/virologia , Dengue/transmissão , Mosquitos Vetores/virologia , Febre Amarela/transmissão , Infecção por Zika virus/transmissão , Animais , Febre de Chikungunya/virologia , Vírus Chikungunya/isolamento & purificação , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Características da Família , Feminino , Humanos , Estudos Longitudinais , Texas , Estados Unidos , Febre Amarela/virologia , Zika virus/isolamento & purificação
19.
Am J Public Health ; 109(3): 387-392, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30676796

RESUMO

The increasing geographical spread and disease incidence of arboviral infections are among the greatest public health concerns in the Americas. The region has observed an increasing trend in dengue incidence in the last decades, evolving from low to hyperendemicity. Yellow fever incidence has also intensified in this period, expanding from sylvatic-restricted activity to urban outbreaks. Chikungunya started spreading pandemically in 2005 at an unprecedented pace, reaching the Americas in 2013. The following year, Zika also emerged in the region with an explosive outbreak, carrying devastating congenital abnormalities and neurologic disorders and becoming one of the greatest global health crises in years. The inadequate arbovirus surveillance in the region and the lack of serologic tests to differentiate among viruses poses substantial challenges. The evidence for vector control interventions remains weak. Clinical management remains the mainstay of arboviral disease control. Currently, only yellow fever and dengue vaccines are licensed in the Americas, with several candidate vaccines in clinical trials. The Global Arbovirus Group of Experts provides in this article an overview of progress, challenges, and recommendations on arboviral prevention and control for countries of the Americas.


Assuntos
Infecções por Arbovirus/epidemiologia , Infecções por Arbovirus/prevenção & controle , Surtos de Doenças/prevenção & controle , Saúde Global/legislação & jurisprudência , Política de Saúde/legislação & jurisprudência , Saúde Pública/legislação & jurisprudência , Américas/epidemiologia , Animais , Humanos
20.
Parasitol Res ; 118(3): 733-742, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30671730

RESUMO

Aedes aegypti and Ae. albopictus are key vectors in the spread of arboviruses such as dengue, chikungunya, yellow fever, and Zika. Triatoma rubrofasciata is an "assassin bug" whose populations and association with humans have dramatically increased and may represent a serious health concern. Control of insect vectors is a logical course of action to prevent the spread of these insect-borne infections. This work presents the leaf essential oil composition, mosquito larvicidal activities, and insect-repellent activity of Severinia monophylla. The essential oil of S. monophylla from Vietnam was obtained by hydrodistillation and analyzed by gas chromatography and mass spectrometry. The major components were sabinene, ß-caryophyllene, bicyclogermacrene, germacrene D, (E)-nerolidol, globulol, and linalool. The leaf essential oil showed remarkable larvicidal activity against Ae. aegypti with LC50 (48 h) of 7.1 µg/mL and Ae. albopictus with LC50 (48 h) of 36 µg/mL. The essential oil also showed repellent activity on T. rubrofasciata at a concentration of 0.5%.


Assuntos
Aedes/efeitos dos fármacos , Dengue/prevenção & controle , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Óleos Voláteis/farmacologia , Rutaceae/química , Triatoma/efeitos dos fármacos , Aedes/parasitologia , Animais , Dengue/transmissão , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Repelentes de Insetos/química , Inseticidas/química , Espectrometria de Massas , Controle de Mosquitos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/parasitologia , Óleos Voláteis/química , Folhas de Planta/química , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Terpenos/química , Terpenos/farmacologia , Vietnã
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