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1.
Artigo em Inglês | MEDLINE | ID: mdl-32491144

RESUMO

Eleven lactating women were inadvertently vaccinated with 17DD yellow fever vaccine in a small city of Sao Paulo State, Brazil. Their infants were being exclusively breast-fed and the breastfeeding was interrupted for 10 days. Serum and breastmilk were collected from the vaccinated mothers and tested for the presence of genomic RNA of the vaccine strain 8, 10 and 15 days after vaccination. Viral RNA was not detected in any of the serum and human milk samples tested and the infants remained asymptomatic. Our result strengthens the effectineness of stopping breastfeeding for 10 days after the inadvertent yellow fever vaccination of lactating women.


Assuntos
Aleitamento Materno/efeitos adversos , Leite Humano/virologia , Vacina contra Febre Amarela/efeitos adversos , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Anticorpos Antivirais/sangue , Antígenos Virais/sangue , Brasil , Feminino , Humanos , Recém-Nascido , RNA Viral/sangue , Febre Amarela/transmissão , Vacina contra Febre Amarela/administração & dosagem
2.
PLoS Negl Trop Dis ; 14(4): e0008219, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32298261

RESUMO

Aedes aegypti is the primary vector of dengue, chikungunya, Zika, and urban yellow fever. Insecticides are often the most effective tools to rapidly decrease the density of vector populations, especially during arbovirus disease outbreaks. However, the intense use of insecticides, particularly pyrethroids, has selected for resistant mosquito populations worldwide. Mutations in the voltage gated sodium channel (NaV) are among the principal mechanisms of resistance to pyrethroids and DDT, also known as "knockdown resistance," kdr. Here we report studies on the origin and dispersion of kdr haplotypes in samples of Ae. aegypti from its worldwide distribution. We amplified the IIS6 and IIIS6 NaV segments from pools of Ae. aegypti populations from 15 countries, in South and North America, Africa, Asia, Pacific, and Australia. The amplicons were barcoded and sequenced using NGS Ion Torrent. Output data were filtered and analyzed using the bioinformatic pipeline Seekdeep to determine frequencies of the IIS6 and IIIS6 haplotypes per population. Phylogenetic relationships among the haplotypes were used to infer whether the kdr mutations have a single or multiple origin. We found 26 and 18 haplotypes, respectively for the IIS6 and IIIS6 segments, among which were the known kdr mutations 989P, 1011M, 1016I and 1016G (IIS6), 1520I, and 1534C (IIIS6). The highest diversity of haplotypes was found in African samples. Kdr mutations 1011M and 1016I were found only in American and African populations, 989P + 1016G and 1520I + 1534C in Asia, while 1534C was present in samples from all continents, except Australia. Based primarily on the intron sequence, IIS6 haplotypes were subdivided into two well-defined clades (A and B). Subsequent phasing of the IIS6 + IIIS6 haplotypes indicates two distinct origins for the 1534C kdr mutation. These results provide evidence of kdr mutations arising de novo at specific locations within the Ae. aegypti geographic distribution. In addition, our results suggest that the 1534C kdr mutation had at least two independent origins. We can thus conclude that insecticide selection pressure with DDT and more recently with pyrethroids is selecting for independent convergent mutations in NaV.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Genes de Insetos , Resistência a Inseticidas/genética , Mutação , Aedes/virologia , África , Alelos , Animais , Ásia , Austrália , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/transmissão , DNA/genética , Dengue/prevenção & controle , Dengue/transmissão , Frequência do Gene , Genótipo , Inseticidas , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , América do Norte , Piretrinas , Febre Amarela/prevenção & controle , Febre Amarela/transmissão , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão
3.
Virol J ; 17(1): 9, 2020 01 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.


Assuntos
Febre Amarela , Vírus da Febre Amarela , Aedes/virologia , Animais , Brasil/epidemiologia , Culicidae/virologia , Surtos de Doenças , Reservatórios de Doenças/virologia , Epidemias , Humanos , Mosquitos Vetores/virologia , Primatas/virologia , Viroses/epidemiologia , Febre Amarela/epidemiologia , Febre Amarela/prevenção & controle , Febre Amarela/transmissão , Vírus da Febre Amarela/imunologia , Vírus da Febre Amarela/isolamento & purificação , Vírus da Febre Amarela/patogenicidade , Zoonoses/epidemiologia , Zoonoses/transmissão , Zoonoses/virologia
4.
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
5.
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
6.
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
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.


Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Febre Amarela/virologia , Vírus da Febre Amarela/fisiologia , Aedes/crescimento & desenvolvimento , Animais , Feminino , Interações Hospedeiro-Patógeno/fisiologia , Humanos , Mosquitos Vetores/fisiologia , Saliva/virologia , Singapura/epidemiologia , Febre Amarela/epidemiologia , Febre Amarela/transmissão
8.
PLoS Negl Trop Dis ; 13(10): e0007615, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31600206

RESUMO

BACKGROUND: The landscape of mosquito-borne disease risk has changed dramatically in recent decades, due to the emergence and reemergence of urban transmission cycles driven by invasive Aedes aegypti and Ae. albopictus. Insecticide resistance is already widespread in the yellow fever mosquito, Ae. Aegypti; is emerging in the Asian tiger mosquito Ae. Albopictus; and is now threatening the global fight against human arboviral diseases such as dengue, yellow fever, chikungunya, and Zika. Because the panel of insecticides available for public health is limited, it is of primary importance to preserve the efficacy of existing and upcoming active ingredients. Timely implementation of insecticide resistance management (IRM) is crucial to maintain the arsenal of effective public health insecticides and sustain arbovirus vector control. METHODOLOGY AND PRINCIPAL FINDINGS: This Review is one of a series being generated by the Worldwide Insecticide resistance Network (WIN) and aims at defining the principles and concepts underlying IRM, identifying the main factors affecting the evolution of resistance, and evaluating the value of existing tools for resistance monitoring. Based on the lessons taken from resistance strategies used for other vector species and agricultural pests, we propose a framework for the implementation of IRM strategies for Aedes mosquito vectors. CONCLUSIONS AND SIGNIFICANCE: Although IRM should be a fixture of all vector control programs, it is currently often absent from the strategic plans to control mosquito-borne diseases, especially arboviruses. Experiences from other public health disease vectors and agricultural pests underscore the need for urgent action in implementing IRM for invasive Aedes mosquitoes. Based on a plan developed for malaria vectors, here we propose some key activities to establish a global plan for IRM in Aedes spp.


Assuntos
Aedes/virologia , Infecções por Arbovirus/transmissão , Arbovirus/fisiologia , Resistência a Inseticidas , Mosquitos Vetores/virologia , Animais , Febre de Chikungunya/transmissão , Dengue/transmissão , Humanos , Controle de Insetos , Inseticidas/farmacologia , Saúde Pública , Febre Amarela/transmissão , Zika virus , Infecção por Zika virus/transmissão
9.
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
10.
PLoS One ; 14(8): e0220106, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31393908

RESUMO

Local climate conditions play a major role in the biology of the Aedes aegypti mosquito, the main vector responsible for transmitting dengue, zika, chikungunya and yellow fever in urban centers. For this reason, a detailed assessment of periods in which changes in climate conditions affect the number of human cases may improve the timing of vector-control efforts. In this work, we develop new machine-learning algorithms to analyze climate time series and their connection to the occurrence of dengue epidemic years for seven Brazilian state capitals. Our method explores the impact of two key variables-frequency of precipitation and average temperature-during a wide range of time windows in the annual cycle. Our results indicate that each Brazilian state capital considered has its own climate signatures that correlate with the overall number of human dengue-cases. However, for most of the studied cities, the winter preceding an epidemic year shows a strong predictive power. Understanding such climate contributions to the vector's biology could lead to more accurate prediction models and early warning systems.


Assuntos
Dengue/epidemiologia , Previsões/métodos , Aedes/metabolismo , Aedes/patogenicidade , Algoritmos , Animais , Brasil/epidemiologia , Febre de Chikungunya/epidemiologia , Febre de Chikungunya/transmissão , Cidades/epidemiologia , Clima , Dengue/transmissão , Vírus da Dengue , Meio Ambiente , Humanos , Insetos Vetores , Aprendizado de Máquina , Mosquitos Vetores , Chuva , Estações do Ano , Temperatura , Febre Amarela/epidemiologia , Febre Amarela/transmissão , Zika virus , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/transmissão
11.
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
12.
Mem Inst Oswaldo Cruz ; 114: e180509, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31066755

RESUMO

BACKGROUND: The outbreak of sylvatic Yellow Fever (SYF) in humans during 2016-2017 in Brazil is one of the greatest in the history of the disease. The occurrence of the disease in areas with low vaccination coverage favoured the dissemination of the disease; therefore, it is necessary to identify the areas vulnerability to the YF virus (YFV) to assist in the adoption of preventive measures. OBJECTIVE: To correlate the physical-environmental elements associated with the occurrence of SYF in humans via a multicriteria analysis. METHODS: For the multicriteria analysis, preponderant elements related to SYF occurrences, including soil usage and coverage, temperature, precipitation, altitude, mosquito transmitters, and non-human primate occurrence areas, were considered. The results were validated by assessing the correlation between the incidence of SYF and the vulnerable areas identified in the multicriteria analysis. RESULTS: Two regions with different vulnerability to the occurrence of the disease were identified in the multicriteria analysis, with emphasis on the southern areas of the state of São Paulo northeast areas of Minas Gerais, and the entire states of Rio de Janeiro and Espírito Santo. The map of SYF vulnerability obtained in the multicriteria analysis coincides with the areas in which cases of the disease have been recorded. The regions that presented the greatest suitability were in fact the municipalities with the highest incidence. MAIN CONCLUSIONS: The multicriteria analysis revealed that the elements that were used are suited for and consistent in the prediction of the areas that are vulnerable to SYF. The results obtained indicate the proximity of the areas that are most vulnerable to the disease to densely populated areas where an Aedes aegypti infestation was observed, which confers a high risk of re-urbanisation of YF.


Assuntos
Aedes/virologia , Febre Amarela/transmissão , Animais , Brasil/epidemiologia , Doenças Endêmicas/prevenção & controle , Sistemas de Informação Geográfica , Humanos , Densidade Demográfica , Vigilância da População , Medição de Risco , Urbanização , Febre Amarela/epidemiologia , Febre Amarela/prevenção & controle , Vacina contra Febre Amarela
13.
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
14.
Semin Diagn Pathol ; 36(3): 170-176, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31006554

RESUMO

In this review we will discuss the epidemiology, clinical characteristics, diagnostic tests, pathologic features, treatment and disease prevention strategies for four mosquito-borne flaviviruses. West Nile and Zika viruses, once thought to be restricted geographically, emerged on the American continent in the first part of the 21st century. They have been constantly in the lay press and have caused a heightened awareness of emerging infections by the public, particularly given the manifestation of microcephaly in congenital Zika syndrome. Yellow fever and dengue viruses, with mosquito vectors similar to West Nile and Zika viruses, are endemic in many tropical areas of the world and produce frequent outbreaks. The global distribution of yellow fever and dengue viruses could also change and has great potential to do so. Factors that could contribute to reemergence of the diseases in areas of the world where they are currently only seen in travelers, include the presence of yellow fever and dengue virus vectors in temperate climates and growing urbanization. These two factors increase potential contact between vectors and naïve human hosts, thus could result in reemergence of yellow fever or dengue virus infections.


Assuntos
Doenças Transmissíveis Emergentes/transmissão , Dengue/transmissão , Flavivirus/isolamento & purificação , Mosquitos Vetores/virologia , Febre do Nilo Ocidental/transmissão , Febre Amarela/transmissão , Infecção por Zika virus/transmissão , Animais , Doenças Transmissíveis Emergentes/virologia , Dengue/virologia , Humanos , Saúde Pública , Febre do Nilo Ocidental/virologia , Febre Amarela/virologia , Infecção por Zika virus/virologia
15.
J Med Entomol ; 56(4): 1154-1158, 2019 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-30927005

RESUMO

The Togolese Republic has a tropical and humid climate which constitutes an ideal environment for mosquitoes to breed and transmit diseases. The Aedes mosquito is known to transmit yellow fever (YF), dengue, chikungunya, and Zika viruses in West Africa. Togo has been suffering from YF virus transmission, despite vaccination efforts. Unfortunately, there is scarcity in the data that reflect mosquito spatial distribution in Togo, specifically possible YF vectors. In the current study, mosquito surveillance efforts targeted areas with confirmed YF cases between July and August 2012. Indoor mosquitoes were collected using knockdown insecticide spraying, whereas Biogents (BG) traps were used to collect outdoor mosquito adults. Mosquito larval surveillance was conducted as well. In total, 17 species were identified. This investigation revealed the presence of medically important vectors in Togo, especially the Aedes aegypti (Linnaeus) (Diptera: Culicidae) which was collected in the four regions. Screening of all pools of female Aedes mosquitoes for YF, by real-time PCR, showed negative results. This is the first record for Coquillettidia flavocincta (Edwards) (Diptera: Culicidae) species in West Africa. This preliminary work serves as a baseline for further mosquito distribution studies in Togo.


Assuntos
Distribuição Animal , Culicidae , Mosquitos Vetores , Animais , Togo , Febre Amarela/transmissão
16.
Emerg Microbes Infect ; 8(1): 218-231, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30866775

RESUMO

The yellow fever virus (YFV) caused a severe outbreak in Brazil in 2016-2018 that rapidly spread across the Atlantic Forest in its most populated region without viral circulation for almost 80 years. A comprehensive entomological survey combining analysis of distribution, abundance and YFV natural infection in mosquitoes captured before and during the outbreak was conducted in 44 municipalities of five Brazilian states. In total, 17,662 mosquitoes of 89 species were collected. Before evidence of virus circulation, mosquitoes were tested negative but traditional vectors were alarmingly detected in 82% of municipalities, revealing high receptivity to sylvatic transmission. During the outbreak, five species were found positive in 42% of municipalities. Haemagogus janthinomys and Hg. leucocelaenus are considered the primary vectors due to their large distribution combined with high abundance and natural infection rates, concurring together for the rapid spread and severity of this outbreak. Aedes taeniorhynchus was found infected for the first time, but like Sabethes chloropterus and Aedes scapularis, it appears to have a potential local or secondary role because of their low abundance, distribution and infection rates. There was no evidence of YFV transmission by Aedes albopictus and Aedes aegypti, although the former was the most widespread species across affected municipalities, presenting an important overlap between the niches of the sylvatic vectors and the anthropic ones. The definition of receptive areas, expansion of vaccination in the most affected age group and exposed populations and the adoption of universal vaccination to the entire Brazilian population need to be urgently implemented.


Assuntos
Surtos de Doenças , Mosquitos Vetores/classificação , Febre Amarela/epidemiologia , Febre Amarela/transmissão , Animais , Brasil/epidemiologia , Cidades , Feminino , Masculino , Mosquitos Vetores/virologia , Filogeografia , Dinâmica Populacional , Vírus da Febre Amarela
17.
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
18.
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
20.
FP Essent ; 476: 11-17, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30615405

RESUMO

Due to rapid globalization and ease of travel, mosquito-borne viral infections are now a concern for family physicians throughout the United States. Zika virus infection is one such concern. It is spread via mosquito bites or by sexual contact with an infected individual. Most patients are asymptomatic, and when symptoms occur, they are mild and nonspecific. The main concern is the potential of the infection to cause fetal anomalies. Dengue is another mosquito-borne viral infection. Symptoms of initial infection are mild, and may include arthralgias. Subsequent infection with a different serotype can cause life-threatening hemorrhagic fever or shock. Chikungunya virus infection is widespread in the Americas and symptoms are similar to those of dengue. However, it can cause a postviral chronic inflammatory rheumatism in up to half of patients. Yellow fever occurs mostly in sub-Saharan Africa and can cause hepatic failure. Encephalitis viruses, most commonly West Nile in the United States and others such as Japanese encephalitis virus, can cause neuroinvasive disease, most often in older adults. Vaccines are available for yellow fever and Japanese encephalitis viruses but the keys to prevention are insect avoidance, mosquito eradication, and use of mosquito repellants.


Assuntos
Culicidae , Dengue , Febre Amarela , Infecção por Zika virus , Animais , Dengue/diagnóstico , Dengue/terapia , Dengue/transmissão , Humanos , Estados Unidos , Febre Amarela/diagnóstico , Febre Amarela/terapia , Febre Amarela/transmissão , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/terapia , Infecção por Zika virus/transmissão
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