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1.
Infect Dis Poverty ; 9(1): 17, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32114982

RESUMO

BACKGROUND: Dengue is a re-emerging public health problem and mosquito-borne infectious disease that is transmitted mainly by Aedes aegypti and Ae. albopictus. Early diagnosis, isolation, and treatment of patients are critical steps for dengue epidemic control, especially to prevent secondary transmission of dengue virus (DENV). However, little is known about defervescent dengue patients as a source of infection. METHODS: This case study describes 1268 dengue patients hospitalized at Guangzhou Eighth People's Hospital from June 2013 to December 2014. The viral loads of each individual were measured using real-time reverse transcription-polymerase chain reaction. Ae. aegypti and Ae. albopictus were exposed to blood meal with gradated dengue viral loads to characterize the relationship between viremia in dengue patients and the vector competence of vector mosquitoes. RESULTS: The viral numbers in the blood were measured, ranging from 108 to 103 copies/ml from day 1 to day 12 after fever onset. Vector competence analysis of Ae. aegypti and Ae. albopictus indicated that viremia > 104 copies/ml can still infect vector mosquitoes, which implied that the defervescent dengue patients might be a source of infection. CONCLUSIONS: The results of this study indicate that some defervescent dengue patients still have sufficient viral load to infect vector mosquitoes. Therefore, the protection against mosquito biting for these people should be extended to prevent secondary transmission events.


Assuntos
Vírus da Dengue/fisiologia , Dengue/epidemiologia , Dengue/transmissão , Mosquitos Vetores/virologia , Aedes/virologia , Animais , Vírus da Dengue/isolamento & purificação , Humanos , Carga Viral
2.
Infect Dis Poverty ; 9(1): 23, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32114983

RESUMO

BACKGROUND: In the Republic of Congo, with two massive outbreaks of chikungunya observed this decade, little is known about the insecticide resistance profile of the two major arbovirus vectors Aedes aegypti and Aedes albopictus. Here, we established the resistance profile of both species to insecticides and explored the resistance mechanisms to help Congo to better prepare for future outbreaks. METHODS: Immature stages of Ae. aegypti and Ae. albopictus were sampled in May 2017 in eight cities of the Republic of the Congo and reared to adult stage. Larval and adult bioassays, and synergist (piperonyl butoxide [PBO]) assays were carried out according to WHO guidelines. F1534C mutation was genotyped in field collected adults in both species and the polymorphism of the sodium channel gene assessed in Ae. aegypti. RESULTS: All tested populations were susceptible to temephos after larval bioassays. A high resistance level was observed to 4% DDT in both species countrywide (21.9-88.3% mortality). All but one population (Ae. aegypti from Ngo) exhibited resistance to type I pyrethroid, permethrin, but showed a full susceptibility to type II pyrethroid (deltamethrin) in almost all locations. Resistance was also reported to 1% propoxur in Ae. aegypti likewise in two Ae. albopictus populations (Owando and Ouesso), and the remaining were fully susceptible. All populations of both species were fully susceptible to 1% fenitrothion. A full recovery of susceptibility was observed in Ae. aegypti and Ae. albopictus when pre-exposed to PBO and then to propoxur and permethrin respectively. The F1534C kdr mutation was not detected in either species. The high genetic variability of the portion of sodium channel spanning the F1534C in Ae. aegypti further supported that knockdown resistance probably play no role in the permethrin resistance. CONCLUSIONS: Our study showed that both Aedes species were susceptible to organophosphates (temephos and fenitrothion), while for other insecticide classes tested the profile of resistance vary according to the population origin. These findings could help to implement better and efficient strategies to control these species in the Congo in the advent of future arbovirus outbreaks.


Assuntos
Aedes/efeitos dos fármacos , Febre de Chikungunya/prevenção & controle , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia , Aedes/virologia , Animais , Congo , Variação Genética , Proteínas de Insetos/genética , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/virologia
3.
Yi Chuan ; 42(2): 153-160, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-32102772

RESUMO

Mosquito-borne diseases have become an important public health issue of global concern because of their high incidence and transmission rate. As a vector for mosquito-borne diseases, studying the interaction mechanism between mosquitoes and mosquito-borne viruses will help control mosquito-borne diseases. The impaired innate immunity and immune barriers evasion caused by mosquito-borne viruses in mosquitoes pose a potential risk for the persistent infection of the virus in mosquitoes and the outbreak of mosquito-borne diseases. The RNA interference (RNAi) pathway, as a powerful antiviral defense barrier in mosquitoes, can inhibit viral replication and transmission by producing a variety of small RNAs to degrade viral RNA. In this review, we summarize the related studies on the innate immune mechanism against mosquito- borne virus infection in mosquitoes about small interfering RNA (siRNA), microRNA (miRNA), and Piwi-interacting RNA (piRNA), aiming to provide a theoretical reference for the prevention and control of mosquito-borne diseases.


Assuntos
Culicidae/virologia , Interferência de RNA , Viroses , Animais , Culicidae/imunologia , Imunidade Inata , Mosquitos Vetores/imunologia , Mosquitos Vetores/virologia , RNA Interferente Pequeno , Viroses/prevenção & controle , Viroses/transmissão
4.
Mem Inst Oswaldo Cruz ; 115: e190390, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049099

RESUMO

The mosquito Culex pipiens s.s. L. occurs as two bioforms that differ in physiology and behaviour affecting virus transmission cycles. To assess the occurrence of Cx. pipiens bioforms in the southernmost limit of its distribution, specimens were collected aboveground in southern Buenos Aires Province and east Patagonia, Argentina. Ten larvae and 25 adults were individually processed and identified by polymerase chain reaction (PCR) amplification of Ace-2 and CQ11 loci. Culex quinquefasciatus Say (one larva, two adults), Cx. pipiens f. molestus (one larva, one adult) and one adult of hybrid origin were identified in Buenos Aires Province; only Cx. pipiens f. molestus was recorded in Patagonia (eight larvae, 21 adults). The potential absence of bioform pipiens and its implications in arbovirus enzootic cycles is discussed.


Assuntos
Culex/fisiologia , Mosquitos Vetores/fisiologia , Distribuição Animal , Animais , Argentina , Culex/genética , Culex/virologia , Encefalite de St. Louis/transmissão , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , Reação em Cadeia da Polimerase , Estações do Ano
6.
Emerg Microbes Infect ; 9(1): 67-77, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31894724

RESUMO

Rapid and significant range expansion of both Zika virus (ZIKV) and its Aedes vector species has resulted in ZIKV being declared a global health threat. Mean temperatures are projected to increase globally, likely resulting in alterations of the transmission potential of mosquito-borne pathogens. To understand the effect of diurnal temperature range on the vectorial capacity of Ae. aegypti and Ae. albopictus for ZIKV, longevity, blood-feeding and vector competence were assessed at two temperature regimes following feeding on infectious blood meals. Higher temperatures resulted in decreased longevity of Ae. aegypti [Log-rank test, χ2, df 35.66, 5, P < 0.001] and a decrease in blood-feeding rates of Ae. albopictus [Fisher's exact test, P < 0.001]. Temperature had a population and species-specific impact on ZIKV infection rates. Overall, Ae. albopictus reared at the lowest temperature regime demonstrated the highest vectorial capacity (0.53) and the highest transmission efficiency (57%). Increased temperature decreased vectorial capacity across groups yet more significant effects were measured with Ae. aegypti relative to Ae. albopictus. The results of this study suggest that future increases in temperature in the Americas could significantly impact vector competence, blood-feeding and longevity, and potentially decrease the overall vectorial capacity of Aedes mosquitoes in the Americas.


Assuntos
Aedes/virologia , Mudança Climática , Mosquitos Vetores/virologia , Infecção por Zika virus/transmissão , Aedes/classificação , Animais , Sangue , Comportamento Alimentar , Feminino , Florida , México , Mosquitos Vetores/fisiologia , New York , Temperatura Ambiente
7.
Int J Infect Dis ; 90: 97-103, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31639520

RESUMO

BACKGROUND: In December 2018, routine surveillance identified an autochthonous outbreak of dengue fever in Muscat Governorate, Oman, a region previously free of dengue fever. METHODS: Routine surveillance confirmed locally acquired cases in the second week of December, leading to a rapid public health response including case management guidance and epidemiological investigations. The main activity was the vector survey using systematic sampling to assess extent of previously unreported Aedes aegypti presence followed by a campaign aimed to eliminate breeding sites of A. aegypti". RESULTS: During a 5-month period, 343 suspected cases were reported from Muscat Governorate with 122 from the outbreak affected area. Out of 207 probable cases eligible for laboratory testing as per guidelines issued, 59 cases were confirmed. The vector elimination campaign started on January 8, 2019 after a media advocacy using television and social media and concluded on January 23. By the end of campaign, the case load had decreased significantly in the affected area with no reports of locally acquired cases from adjoining areas of Muscat Governorate, indicating no further spread. CONCLUSIONS: Rapid notification and early community-wide, extensive vector control activities effectively contained the autochthonous dengue fever virus outbreak.


Assuntos
Dengue/epidemiologia , Surtos de Doenças , Aedes/virologia , Animais , Vírus da Dengue/isolamento & purificação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Omã , Vigilância em Saúde Pública
8.
Arch Virol ; 165(2): 445-450, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31834526

RESUMO

An outbreak of chikungunya virus (CHIKV) infection occurred in southwest Bangkok during the 2018 rainy season. The envelope glycoprotein E1 gene sequence of the infecting strain belonged to an East/Central/South African lineage with alanine at residue 226. Mutations in the predicted E1 (K211E) and E2 (V264A) proteins of CHIKV were identified in CHIKV-infected patients and in an Aedes aegypti mosquito. Analysis of the complete genome sequences showed marked differences from the strains causing previous outbreaks in Thailand in 2008-2009 and 2013 but showed similarities to strains from more recent CHIKV outbreaks in South and Southeast Asia.


Assuntos
Febre de Chikungunya/virologia , Vírus Chikungunya/genética , Vírus Chikungunya/isolamento & purificação , Aedes/virologia , Animais , Sequência de Bases , Surtos de Doenças , Feminino , Genoma Viral/genética , Humanos , Mosquitos Vetores/virologia , Mutação/genética , Filogenia , RNA Viral/genética , Análise de Sequência de DNA/métodos , Tailândia , Proteínas do Envelope Viral/genética
9.
PLoS Pathog ; 15(12): e1008218, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31790509

RESUMO

Dengue virus (DENV) transmission by mosquitoes is a time-dependent process that begins with the consumption of an infectious blood-meal. DENV infection then proceeds stepwise through the mosquito from the midgut to the carcass, and ultimately to the salivary glands, where it is secreted into saliva and then transmitted anew on a subsequent bite. We examined viral kinetics in tissues of the Aedes aegypti mosquito over a finely graded time course, and as per previous studies, found that initial viral dose and serotype strain diversity control infectivity. We also found that a threshold level of virus is required to establish body-wide infections and that replication kinetics in the early and intermediate tissues do not predict those of the salivary glands. Our findings have implications for mosquito GMO design, modeling the contribution of transmission to vector competence and the role of mosquito kinetics in the overall DENV epidemiological landscape.


Assuntos
Vírus da Dengue , Dengue/virologia , Interações Hospedeiro-Parasita/fisiologia , Mosquitos Vetores/virologia , Aedes , Animais , Cinética , Replicação Viral
10.
PLoS Pathog ; 15(12): e1008199, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31815960

RESUMO

More than half of the world population is at risk of dengue virus (DENV) infection because of the global distribution of its mosquito vectors. DENV is an envelope virus that relies on host lipid membranes for its life-cycle. Here, we characterized how DENV hijacks the mosquito lipidome to identify targets for novel transmission-blocking interventions. To describe metabolic changes throughout the mosquito DENV cycle, we deployed a Liquid chromatography-high resolution mass spectrometry (LC-HRMS) workflow including spectral similarity annotation in cells, midguts and whole mosquitoes at different times post infection. We revealed a major aminophospholipid reconfiguration with an overall early increase, followed by a reduction later in the cycle. We phylogenetically characterized acylglycerolphosphate acyltransferase (AGPAT) enzyme isoforms to identify those that catalyze a rate-limiting step in phospholipid biogenesis, the acylation of lysophosphatidate to phosphatidate. We showed that DENV infection decreased AGPAT1, but did not alter AGPAT2 expression in cells, midguts and mosquitoes. Depletion of either AGPAT1 or AGPAT2 increased aminophospholipids and partially recapitulated DENV-induced reconfiguration before infection in vitro. However, only AGPAT1 depletion promoted infection by maintaining high aminophospholipid concentrations. In mosquitoes, AGPAT1 depletion also partially recapitulated DENV-induced aminophospholipid increase before infection and enhanced infection by maintaining high aminophospholipid concentrations. These results indicate that DENV inhibition of AGPAT1 expression promotes infection by increasing aminophospholipids, as observed in the mosquito's early DENV cycle. Furthermore, in AGPAT1-depleted mosquitoes, we showed that enhanced infection was associated with increased consumption/redirection of aminophospholipids. Our study suggests that DENV regulates aminophospholipids, especially phosphatidylcholine and phosphatidylethanolamine, by inhibiting AGPAT1 expression to increase aminophospholipid availability for virus multiplication.


Assuntos
1-Acilglicerol-3-Fosfato O-Aciltransferase/metabolismo , Vírus da Dengue/metabolismo , Proteínas de Insetos/metabolismo , Mosquitos Vetores/metabolismo , Mosquitos Vetores/virologia , Aedes , Animais , Interações Hospedeiro-Parasita/fisiologia , Fosfolipídeos/metabolismo
11.
PLoS Negl Trop Dis ; 13(12): e0007985, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31887138

RESUMO

INTRODUCTION: Dengue is the most important mosquito-borne diseases worldwide but was considered scarce in West-Central Africa. During the last decade, dengue outbreaks have increasingly been reported in urban foci in this region suggesting major epidemiological changes. However, in Central Africa where both vectors, Aedes aegypti and Aedes albopictus are well established, the role of each species in dengue transmission remains poorly investigated. METHODOLOGY/PRINCIPAL FINDINGS: Field-collected strains of Ae. aegypti and Ae. albopictus from different ecological settings in Central Africa were experimentally challenged with dengue 2 virus (DENV-2). Mosquitoes were analysed at 14- and 21-days post-infection. Analysis provide evidence that both Ae. aegypti and Ae. albopictus in Central Africa were able to transmit dengue virus with Ae. aegypti exhibiting a higher transmission rate. Unexpectedly, two Ae. aegypti populations from Bénoué and Maroua, in northern Cameroon, were not able to transmit DENV-2. CONCLUSIONS/SIGNIFICANCE: We conclude that both Ae. aegypti and Ae. albopictus are susceptible to DENV-2 and may intervene as active dengue vectors. These findings highlight the urgent need to plan a vector surveillance program and control methods against dengue vectors in Central Africa in order to prevent future outbreaks.


Assuntos
Aedes/crescimento & desenvolvimento , Aedes/virologia , Vírus da Dengue/crescimento & desenvolvimento , Dengue/epidemiologia , Dengue/transmissão , Transmissão de Doença Infecciosa , Tropismo Viral , África Central/epidemiologia , Animais , Feminino , Humanos , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/virologia , Medição de Risco
12.
PLoS Negl Trop Dis ; 13(12): e0007988, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31877132

RESUMO

BACKGROUND: Detecting and monitoring the transmission of arboviruses such as Zika virus (ZIKV), dengue virus, and chikungunya virus is critical for prevention and control activities. Previous work has compared the ability of different human-focused surveillance strategies to detect ZIKV transmission in U.S. counties where no known transmission had occurred, but whether virological surveillance in mosquitoes could represent an effective surveillance system is unclear. OBJECTIVES: We leveraged a unique set of data from human and virological surveillance in Ae. aegypti during the 2016 ZIKV epidemic in Caguas, Puerto Rico, to compare alternative strategies for detecting and monitoring ZIKV activity. METHODS: We developed a simulation model for mosquito and human surveillance strategies and simulated different transmission scenarios with varying infection rates and mosquito trap densities. We then calculated the expected weekly number of detected infections, the probability of detecting transmission, and the number of tests needed and compared the simulations with observed data from Caguas. RESULTS: In simulated high transmission scenarios (1 infection per 1,000 people per week), the models demonstrated that both approaches had estimated probabilities of detection of greater than 78%. In simulated low incidence scenarios, vector surveillance had higher sensitivity than human surveillance and sensitivity increased with more traps, more trapping effort, and testing. In contrast, the actual data from Caguas indicated that human virological surveillance was more sensitive than vector virological surveillance during periods of both high and low transmission. CONCLUSION: In scenarios where human surveillance is not possible or when transmission intensity is very low, virological surveillance in Ae. aegypti may be able to detect and monitor ZIKV epidemic activity. However, surveillance for humans seeking care for Zika-like symptoms likely provides an equivalent or more sensitive indicator of transmission intensity in most circumstances.


Assuntos
Aedes/virologia , Transmissão de Doença Infecciosa/prevenção & controle , Monitoramento Epidemiológico , Mosquitos Vetores/virologia , Infecção por Zika virus/prevenção & controle , Zika virus/isolamento & purificação , Animais , Simulação por Computador , Feminino , Incidência , Porto Rico/epidemiologia , Sensibilidade e Especificidade , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/transmissão
13.
PLoS One ; 14(12): e0225250, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31869335

RESUMO

Vector borne diseases are a continuing global threat to both human and animal health. The ability of vectors such as mosquitos to cover large distances and cross country borders undetected provide an ever-present threat of pathogen spread. Many diseases can infect multiple vector species, such that even if the climate is not hospitable for an invasive species, indigenous species may be susceptible and capable of transmission such that one incursion event could lead to disease establishment in these species. Here we present a consensus modelling methodology to estimate the habitat suitability for presence of mosquito species in the UK deemed competent for Rift Valley fever virus (RVF) and demonstrate its application in an assessment of the relative risk of establishment of RVF virus in the UK livestock population. The consensus model utilises observed UK mosquito surveillance data, along with climatic and geographic prediction variables, to inform six independent species distribution models; the results of which are combined to produce a single prediction map. As a livestock host is needed to transmit RVF, we then combine the consensus model output with existing maps of sheep and cattle density to predict the areas of the UK where disease is most likely to establish in local mosquito populations. The model results suggest areas of high suitability for RVF competent mosquito species across the length and breadth of the UK. Notable areas of high suitability were the South West of England and coastal areas of Wales, the latter of which was subsequently predicted to be at higher risk for establishment of RVF due to higher livestock densities. This study demonstrates the applicability of outputs of species distribution models to help predict hot-spots for risk of disease establishment. While there is still uncertainty associated with the outputs we believe that the predictions are an improvement on just using the raw presence points from a database alone. The outputs can also be used as part of a multidisciplinary approach to inform risk based disease surveillance activities.


Assuntos
Distribuição Animal , Gado/virologia , Modelos Teóricos , Mosquitos Vetores/virologia , Febre do Vale de Rift/epidemiologia , Vírus da Febre do Vale do Rift , Animais , Clima , Surtos de Doenças , Vetores de Doenças , Reino Unido
14.
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
15.
PLoS Negl Trop Dis ; 13(11): e0007346, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31693659

RESUMO

BACKGROUND: Aedes aegypti is a vector mosquito of major public health importance, transmitting arthropod-borne viruses (arboviruses) such as chikungunya, dengue, yellow fever and Zika viruses. Wild mosquito populations are persistently infected at high prevalence with insect-specific viruses that do not replicate in vertebrate hosts. In experimental settings, acute infections with insect-specific viruses have been shown to modulate arbovirus infection and transmission in Ae. aegypti and other vector mosquitoes. However, the impact of persistent insect-specific virus infections, which arboviruses encounter more commonly in nature, has not been investigated extensively. Cell lines are useful models for studying virus-host interactions, however the available Ae. aegypti cell lines are poorly defined and heterogenous cultures. METHODOLOGY/PRINCIPLE FINDINGS: We generated single cell-derived clonal cell lines from the commonly used Ae. aegypti cell line Aag2. Two of the fourteen Aag2-derived clonal cell lines generated harboured markedly and consistently reduced levels of the insect-specific bunyavirus Phasi Charoen-like virus (PCLV) known to persistently infect Aag2 cells. In contrast to studies with acute insect-specific virus infections in cell culture and in vivo, we found that pre-existing persistent PCLV infection had no major impact on the replication of the flaviviruses dengue virus and Zika virus, the alphavirus Sindbis virus, or the rhabdovirus vesicular stomatitis virus. We also performed a detailed characterisation of the morphology, transfection efficiency and immune status of our Aag2-derived clonal cell lines, and have made a clone that we term Aag2-AF5 available to the research community as a well-defined cell culture model for arbovirus-vector interaction studies. CONCLUSIONS/SIGNIFICANCE: Our findings highlight the need for further in vivo studies that more closely recapitulate natural arbovirus transmission settings in which arboviruses encounter mosquitoes harbouring persistent rather than acute insect-specific virus infections. Furthermore, we provide the well-characterised Aag2-derived clonal cell line as a valuable resource to the arbovirus research community.


Assuntos
Aedes/virologia , Arbovirus/crescimento & desenvolvimento , Coinfecção/virologia , Mosquitos Vetores/virologia , Orthobunyavirus/crescimento & desenvolvimento , Replicação Viral , Alphavirus/crescimento & desenvolvimento , Animais , Arbovirus/genética , Sequência de Bases , Técnicas de Cultura de Células/métodos , Linhagem Celular , Vírus da Dengue/crescimento & desenvolvimento , Flavivirus/genética , Flavivirus/crescimento & desenvolvimento , Genoma Viral , Interações Hospedeiro-Patógeno/fisiologia , Orthobunyavirus/genética , Vírus de RNA/genética , Vírus de RNA/crescimento & desenvolvimento , Rhabdoviridae/crescimento & desenvolvimento , Vírus Sindbis/crescimento & desenvolvimento , Transfecção , Zika virus/crescimento & desenvolvimento
16.
Braz J Med Biol Res ; 52(11): e8339, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31721902

RESUMO

A progressive increase in the circulation of arboviruses in tropical countries has been observed, accounting for 700,000 yearly deaths in the world. The main objective of this article was to identify the presence of Zika (ZIKV), dengue (DENV), and Chikungunya (CHIKV) viruses in immature stages of Aedes aegypti and Ae. albopictus. Household collections of immature phases of the vectors were carried out in the years 2015 and 2016. A total of 2902 dwellings were visited and the rate of infestation with larvae and pupae of Aedes mosquitoes was 283/1462 (19.4%) in March 2015 and 55/1440 (3.8%) in June 2015. In March 2015, 907 larvae/pupae were collected (583 or 64.3% of Ae. aegypti and 324 or 35.7% of Ae. albopictus) while in June 2015 there was a reduction in the number of immature forms found: 197 larvae/pupae (121 or 61.4% of Ae. aegypti and 76 or 38.6% of Ae. albopictus). This reduction was accompanied by a decrease in suspected human ZIKV cases from March to June 2015. The RT-qPCR performed in 18 pools identified that three (two of Ae. aegypti and one of Ae. albopictus) were positive for ZIKV, and none were positive for DENV or CHIKV. Our findings demonstrated that ZIKV was present in immature stages of insect vectors in the study region at least five months prior to the peak of ZIKV associated cases. Xenomonitoring of immature phases of the vectors may prove useful for predicting outbreaks.


Assuntos
Aedes/virologia , Vírus Chikungunya/isolamento & purificação , Vírus da Dengue/isolamento & purificação , Mosquitos Vetores/virologia , Zika virus/isolamento & purificação , Aedes/classificação , Animais , Humanos , Mosquitos Vetores/classificação , RNA Viral/análise , Reação em Cadeia da Polimerase em Tempo Real , Estações do Ano , Infecção por Zika virus/transmissão
17.
PLoS Negl Trop Dis ; 13(11): e0007774, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31770384

RESUMO

Urban livestock provides an important source of food and income, but it may increase the risks for disease transmission. Vectors, such as mosquitoes, might increase and thereby cause an enhanced transmission of infectious diseases, such as dengue fever; considered the most important mosquito-borne viral disease globally. This cross-sectional study evaluated the awareness of dengue fever and investigated how the presence of dengue vectors is affected by the keeping of livestock in urban households in the city of Hanoi, Vietnam. From February to March 2018, during the season of lowest occurrence of dengue in Hanoi, 140 households were interviewed, of which 69 kept livestock. A general trend was observed; respondents living in the Dan Phuong district, a peri-urban district, had better knowledge and practice regarding dengue as compared to the urban Ha Dong district. In total, 3899 mosquitoes were collected and identified, of which 52 (1.33%) were Aedes species. A significant difference between the two districts was observed, with more households in Ha Dong having Aedes spp. mosquitoes (p = 0.02) and a higher incidence of dengue fever (p = 0.001). There was no significant association between livestock-rearing and the presence of Aedes spp. mosquitoes (p = 0.955), or between livestock-rearing and the incidence of dengue fever (p = 0.08). In conclusion, this study could not find any indication that households keeping livestock were at higher risk of dengue virus infections in Hanoi during the season of lowest occurrence of dengue, but clearly indicated the need of more information provided to urban inhabitants, particularly on personal protection.


Assuntos
Dengue/epidemiologia , Gado/virologia , População Urbana , Adolescente , Adulto , Aedes/classificação , Aedes/virologia , Idoso , Idoso de 80 Anos ou mais , Animais , Cidades , Estudos Transversais , Dengue/transmissão , Vírus da Dengue , Características da Família , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Estações do Ano , Inquéritos e Questionários , Vietnã/epidemiologia , Adulto Jovem
18.
BMC Infect Dis ; 19(1): 1002, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31775646

RESUMO

BACKGROUND: Dengue is the most prevalent mosquito-borne disease in the world, with China affected seriously in recent years. 65.8% of dengue cases identified in mainland China since 2005 were reported from the city of Guangzhou. METHODS: In this study, we described the incidence rate and distribution of dengue cases using data collected form National Notifiable Infectious Disease Reporting Information System data in Guangzhou for 2001 to 2016. All dengue cases were investigated using standardized questionnaire. RESULTS: A total of 42,469 dengue cases were reported, with an average annual incidence rate of 20.99 per 100,000 resident population. Over this time period, the incidence rate of indigenous cases increased. Dengue affected areas also expanded sharply geographically from 58.1% of communities affected during 2001-2005 to 96.4% of communities affected in 2011-2016. Overall 95.30% of the overseas imported cases were reported during March and December, while 99.79% of indigenous cases were reported during July and November. All four dengue virus serotypes were identified both in imported cases and indigenous cases. The Aedes albopictus mosquito was the only vector for dengue transmission in the area. CONCLUSIONS: Guangzhou has become the dengue epicenter in mainland China. Control strategies for dengue should be adjusted to the epidemiological characteristics above and intensive study need to be conducted to explore the factors that driving the rapid increase of dengue.


Assuntos
Vírus da Dengue/imunologia , Dengue/epidemiologia , Monitoramento Epidemiológico , Adolescente , Adulto , Aedes/virologia , Fatores Etários , Idoso , Animais , Criança , Pré-Escolar , China/epidemiologia , Vírus da Dengue/isolamento & purificação , Notificação de Doenças/legislação & jurisprudência , Surtos de Doenças/prevenção & controle , Feminino , Humanos , Incidência , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Prevalência , Sorogrupo , Inquéritos e Questionários , Adulto Jovem
19.
BMC Infect Dis ; 19(1): 1004, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31775718

RESUMO

BACKGROUND: Chikungunya virus (CHIKV) is a widespread mosquito-borne virus representing a serious challenge to public health. The largest outbreak in the Middle-East was recorded in 2016-2017 in Pakistan. Sistan and Baluchistan Province of Iran shares a wide border with Pakistan; accordingly, introduction of CHIKV from Pakistan to Iran seems to be probable. The current study is aimed at investigating CHIKV infection in Sistan and Baluchistan Province. METHODS: Between April 2017 and June 2018, a total of 159 serum samples of CHIK suspected cases from 10 cities of Sistan and Baluchistan Province were tested by molecular and serological assays. Samples obtained up to 4 days after onset of illness were tested by real time PCR (n = 8). Samples collected 5-10 days after disease onset were subjected to ELISA, as well as real time PCR tests (n = 72). Samples obtained after the 10th day of disease onset were tested by only ELISA (n = 79). Phylogenetic analysis of real time PCR positive samples was carried out by sequencing of a 1014-bp region of Envelope 1 gene (E1 gene). Chi-square and independent t tests were used to evaluate the association between variables and CHIKV infection. RESULTS: In total, 40 (25.1%) out of 159 samples tested positive either by real time PCR or ELISA tests.Out of 151 samples serologically analyzed, 19 (12.6%) and 28 (18.6%) cases were positive for anti-CHIKV IgM and anti-CHIKV IgG antibodies, respectively. Of 80 samples tested by real time PCR, CHIKV RNA was detected in 11 (13.7%) sera, all of them had recent travel history to Pakistan. Additionally, phylogenetic analysis of 5 samples indicated their similarity with recent isolates of Pakistan outbreak 2016-2017 belonging to Indian Ocean sub-lineage of ECSA genotype. A significant correlation between abroad travel history and CHIKV infection was observed (P < 0.001). The most common clinical symptoms included fever, arthralgia/arthritis, myalgia, headache, and chill. CONCLUSIONS: These results present substantial evidence of CHIKV introduction to Iran from Pakistan and emphasize the need for the enhancement of surveillance system and preventive measures.


Assuntos
Febre de Chikungunya/epidemiologia , Vírus Chikungunya/genética , Vírus Chikungunya/imunologia , Doenças Transmissíveis Importadas/virologia , Surtos de Doenças , Adolescente , Adulto , Animais , Anticorpos Antivirais/sangue , Artralgia/epidemiologia , Vírus Chikungunya/isolamento & purificação , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Febre/epidemiologia , Genótipo , Humanos , Irã (Geográfico)/epidemiologia , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Paquistão/epidemiologia , Filogenia , Reação em Cadeia da Polimerase em Tempo Real , Estudos Retrospectivos , Viagem , Proteínas do Envelope Viral/genética , Adulto Jovem
20.
PLoS Negl Trop Dis ; 13(11): e0007853, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31751338

RESUMO

Chikungunya virus (Togaviridae, Alphavirus; CHIKV) is a mosquito-borne global health threat that has been transmitted transiently in the southeastern United States. A primary CHIKV mosquito vector, Aedes aegypti, was recently established in the populous state of California, but the vector competence of Californian mosquitoes is unknown. Explosive CHIKV epidemics since 2004 have been associated with the acquisition of mosquito-adaptive mutations that enhance transmission by Ae. aegypti or Ae. albopictus. As a highly mutable RNA virus, CHIKV has the potential for extensive and rapid genetic diversification in vertebrate hosts and mosquito vectors. We previously demonstrated that expansion of CHIKV diversity in cell culture allows for greater adaptability to novel selection pressures, and that CHIKV fidelity variants are able to diversify more than wildtype (WT) CHIKV in mice. The evolution of intra-vector CHIKV populations and the correlation between CHIKV population diversity and infectivity and transmissibility in mosquitoes has not yet been studied. Here, we address these gaps in knowledge via experimental infection of Ae. aegypti from California with WT and fidelity variant CHIKV. We show that Ae. aegypti from California are highly competent vectors for CHIKV. We also report that CHIKV fidelity variants diversify more than WT in mosquitoes and exhibit attenuated infectivity at the level of the midgut. Furthermore, we demonstrate that intra-vector populations of CHIKV are subjected to purifying selection in mosquito bodies, and sequences of non-coding CHIKV regions are highly conserved. These findings will inform public health risk assessment for CHIKV in California and improve our understanding of constraints to CHIKV evolution in mosquitoes.


Assuntos
Adaptação Biológica , Aedes/virologia , Vírus Chikungunya/classificação , Vírus Chikungunya/genética , Variação Genética , Mosquitos Vetores/virologia , Animais , Biota , California , Vírus Chikungunya/isolamento & purificação , Feminino , Genótipo , Seleção Genética
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