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2.
Mem Inst Oswaldo Cruz ; 115: e200012, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32520074

RESUMO

In Argentina, many Flavivirus were recognised including West Nile virus (WNV). During 2009 several strains of Culex Flavivirus (CxFV), an insect-specific flavivirus, were isolated in the same region where circulation of WNV was detected. Hence, the objective of this study was to analyse the effect of co-infection in vitro assays using CxFV and WNV Argentinean strains in order to evaluate if CxFV could affect WNV replication. Our results showed that WNV replication was suppressed when multiplicity of infection (MOI) for CxFV was 10 or 100 times higher than WNV. Nevertheless, in vivo assays are necessary in order to evaluate the superinfection exclusion potential.


Assuntos
Aedes/virologia , Culex/virologia , Flavivirus/fisiologia , Insetos Vetores/virologia , Superinfecção/virologia , Vírus do Nilo Ocidental/patogenicidade , Animais , Argentina , Linhagem Celular , Ensaio de Placa Viral
3.
BMC Infect Dis ; 20(1): 371, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32448116

RESUMO

BACKGROUND: Zika virus (ZIKV, genus Flavivirus, family Flaviviridae) is transmitted mainly by Aedes mosquitoes. This virus has become an emerging concern of global public health with recent epidemics associated to neurological complications in the pacific and America. ZIKV is the most frequently amplified arbovirus in southeastern Senegal. However, this virus and its adult vectors are undetectable during the dry season. The aim of this study was to investigate how ZIKV and its vectors are maintained locally during the dry season. METHODS: Soil, sand, and detritus contained in 1339 potential breeding sites (tree holes, rock holes, fruit husks, discarded containers, used tires) were collected in forest, savannah, barren and village land covers and flooded for eggs hatching. The emerging larvae were reared to adult, identified, and blood fed for F1 production. The F0 and F1 adults were identified and tested for ZIKV by Reverse Transcriptase-Real time Polymerase Chain Reaction. RESULTS: A total of 1016 specimens, including 13 Aedes species, emerged in samples collected in the land covers and breeding sites investigated. Ae. aegypti was the dominant species representing 56.6% of this fauna with a high plasticity. Ae. furcifer and Ae. luteocephalus were found in forest tree holes, Ae. taylori in forest and village tree holes, Ae. vittatus in rock holes. ZIKV was detected from 4 out of the 82 mosquito pools tested. Positive pools included Ae. bromeliae (2 pools), Ae. unilineatus (1 pool), and Ae. vittatus (1 pool), indicating that the virus is maintained in these Aedes eggs during the dry season. CONCLUSION: Our investigation identified breeding sites types and land cover classes where several ZIKV vectors are maintained, and their maintenance rates during the dry season in southeastern Senegal. The maintenance of the virus in these vectors in nature could explain its early amplification at the start of the rainy season in this area.


Assuntos
Aedes/virologia , Secas , Mosquitos Vetores/fisiologia , Estações do Ano , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/transmissão , Zika virus/genética , Aedes/classificação , Aedes/fisiologia , Animais , Arbovirus/genética , Feminino , Florestas , Larva , Masculino , RNA Viral/genética , Chuva , Reprodução , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Areia/virologia , Senegal/epidemiologia , Microbiologia do Solo , Árvores/virologia , Infecção por Zika virus/virologia
4.
Salud Publica Mex ; 62(2): 203-210, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32237563

RESUMO

OBJECTIVE: To gain a better understanding of the Zika virus (ZIKV) vector transmission in Mexico, we determined the vector competence of a local population of Ae. aegypti (Acapulco, Guerrero) for a strain of ZIKV isolated from a Mexican febrile patient. MATERIALS AND METHODS: Eggs were hatched and larvae were reared under controlled conditions. After five days post-emergence, female mosquitoes were fed an infectious blood-meal containing ZIKV. Mosquitoes were analyzed at 4, 7 and 14-day post-infection (dpi). Infection (gut), dissemination (wings, legs and heads) and potential transmission (salivary glands) were assessed by RT-qPCR. The Rockefeller Ae. aegypti strain was used as ZIKV infection control. RESULTS: ZIKV infection, dissemination, and potential transmission rates were 96.2, 96.1 and 93.2%, respectively. CONCLUSIONS: Ae. aegypti (F1) from Acapulco were very susceptible to ZIKV infection, and showed similar vector competence to that of the susceptible Rockefeller strain. To our knowledge, this is the first report of vector competence for ZIKV performed in a Mexican laboratory.


Assuntos
Aedes/virologia , Zika virus/fisiologia , Animais , Feminino , México , Mosquitos Vetores
5.
PLoS Negl Trop Dis ; 14(4): e0007518, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32287269

RESUMO

Newly emerging or re-emerging arthropod-borne viruses (arboviruses) are important causes of human morbidity and mortality worldwide. Arboviruses such as Dengue (DENV), Zika (ZIKV), Chikungunya (CHIKV), and West Nile virus (WNV) have undergone extensive geographic expansion in the tropical and sub-tropical regions of the world. In the Americas the main vectors of DENV, ZIKV, and CHIKV are mosquito species adapted to urban environments, namely Aedes aegypti and Aedes albopictus, whereas the main vector of WNV is Culex quinquefasciatus. Given the widespread distribution in the Americas and high permissiveness to arbovirus infection, these mosquito species may play a key role in the epidemiology of other arboviruses normally associated with sylvatic vectors. Here, we test this hypothesis by determining the vector competence of Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus to Mayaro (MAYV) virus, a sylvatic arbovirus transmitted mainly by Haemagogus janthinomys that has been causing an increasing number of outbreaks in South America, namely in Brazil. Using field mosquitoes from Brazil, female mosquitoes were experimentally infected, and their competence for infection and transmission rates of MAYV was evaluated. We found consistent infection rate for MAYV in Ae. aegypti (57.5%) and Ae. albopictus (61.6%), whereas very low rates were obtained for Cx. quinquefasciatus (2.5%). Concordantly, we observed high potential transmission ability in Ae. aegypti and Ae. albopictus (69.5% and 71.1% respectively), in contrast to Cx. quinquefasciatus, which could not transmit the MAYV. Notably, we found that very low quantities of virus present in the saliva (undetectable by RT-qPCR) were sufficiently virulent to guarantee transmission. Although Ae. aegypti and Ae. albopictus mosquitoes are not the main vectors for MAYV, our studies suggest that these mosquitoes could play a significant role in the transmission of this arbovirus, since both species showed significant vector competence for MAYV (Genotype D), under laboratory conditions.


Assuntos
Aedes/virologia , Infecções por Alphavirus/virologia , Alphavirus/isolamento & purificação , Culex/virologia , Transmissão de Doença Infecciosa , Alphavirus/genética , Alphavirus/crescimento & desenvolvimento , Infecções por Alphavirus/transmissão , Animais , Brasil , Feminino , Reação em Cadeia da Polimerase em Tempo Real , Saliva/virologia , Carga Viral
6.
PLoS One ; 15(4): e0230486, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236142

RESUMO

Aedes aegypti transmitted arboviral diseases are of significant importance in Colombia, particularly since the 2014/2015 introduction of chikungunya and Zika in the Americas and the increasing spread of dengue. In response, the Colombian government initiated the scaling-up of a community-based intervention under inter and multi-sector partnerships in two out of four sectors in Girardot, one of the most hyper-endemic dengue cities in the country. Using a quasi-experimental research design a scaled-up community-led Aedes control intervention was assessed for its capacity to reduce dengue from January 2010 to August 2017 in Girardot, Colombia. Reported dengue cases, and associated factors were analysed from available data sets from the Colombian disease surveillance systems. We estimated the reduction in dengue cases before and after the intervention using, Propensity Score Matching and an Autoregressive Moving Average model for robustness. In addition, the differences in dengue incidence among scaling-up phases (pre-implementation vs sustainability) and between treatment groups (intervention and control areas) were modelled. Evidence was found in favour of the intervention, although to maximise impact the scaling-up of the intervention should continue until it covers the remaining sectors. It is expected that a greater impact of the intervention can be documented in the next outbreak of dengue in Girardot.


Assuntos
Aedes/fisiologia , Dengue/patologia , Controle de Mosquitos/métodos , Avaliação de Programas e Projetos de Saúde , Aedes/virologia , Animais , Cidades , Colômbia/epidemiologia , Dengue/epidemiologia , Surtos de Doenças , Humanos
7.
Am J Trop Med Hyg ; 102(5): 964-970, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32228777

RESUMO

Two confirmed human cases of Zika virus (ZIKV) were reported in the district of Miri, Sarawak, in 2016. Following that, a mosquito-based ZIKV surveillance study was conducted within 200-m radius from the case houses. Mosquito surveillance was conducted using five different methods, that is, biogents sentinel mosquito (BG) sentinel trap, modified sticky ovitrap, resting catch, larval surveillance, and conventional ovitrap. A total of 527 and 390 mosquito samples were obtained from the case houses in two localities, namely, Kampung Lopeng and Taman Shang Ri La, Miri, Sarawak, respectively. All mosquitoes collected were identified, which consisted of 11 species. Aedes albopictus, both the adult and larval stages, was the dominant species. Resting catch method obtained the highest number of adult mosquitoes (67%), whereas ovitrap showed the highest catch for larval mosquitoes (84%). Zika virus was detected in both adults and larvae of Ae. albopictus together with adults of Culex gelidus, and Culex quinquefasciatus using the real-time reverse transcriptase polymerase chain reaction (PCR) technique. It was noteworthy that Ae. albopictus positive with ZIKV were caught and obtained from four types of collection method. By contrast, Cx. gelidus and Culex quinquefasciatus adults collected from sticky ovitraps were also found positive with ZIKV. This study reveals vital information regarding the potential vectors of ZIKV and the possibility of transovarian transmission of the virus in Malaysia. These findings will be essentials for vector control program managers to devise preparedness and contingency plans of prevention and control of the arboviral disease.


Assuntos
Culicidae/virologia , Mosquitos Vetores/virologia , Infecção por Zika virus/epidemiologia , Aedes/virologia , Animais , Culex/virologia , Feminino , Humanos , Malásia/epidemiologia , Masculino , Vigilância da População , Reação em Cadeia da Polimerase em Tempo Real , Infecção por Zika virus/etiologia , Infecção por Zika virus/transmissão
8.
Parasit Vectors ; 13(1): 188, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32276649

RESUMO

BACKGROUND: Vector-borne diseases are a major public health concern and cause significant morbidity and mortality. Zika virus (ZIKV) is the etiologic agent of a massive outbreak in the Americas that originated in Brazil in 2015 and shows a strong association with congenital ZIKV syndrome in newborns. Cache Valley virus (CVV) is a bunyavirus that causes mild to severe illness in humans and ruminants. In this study, we investigated the vector competence of Virginia mosquitoes for ZIKV and CVV to explore their abilities to contribute to potential outbreaks. METHODS: To determine vector competence, mosquitoes were fed a blood meal comprised of defibrinated sheep blood and virus. The presence of midgut or salivary gland barriers to ZIKV infection were determined by intrathoracic inoculation vs oral infection. After 14-days post-exposure, individual mosquitoes were separated into bodies, legs and wings, and saliva expectorant. Virus presence was detected by plaque assay to determine midgut infection, dissemination, and transmission rates. RESULTS: Transmission rates for Ae. albopictus orally infected (24%) and intrathoracically inoculated (63%) with ZIKV was similar to Ae. aegypti (48% and 71%, respectively). Transmission rates of ZIKV in Ae. japonicus were low, and showed evidence of a midgut infection barrier demonstrated by low midgut infection and dissemination rates from oral infection (3%), but increased transmission rates after intrathoracic inoculation (19%). Aedes triseriatus was unable to transmit ZIKV following oral infection or intrathoracic inoculation. CVV transmission was dose-dependent where mosquitoes fed high titer (ht) virus blood meals developed higher rates of midgut infection, dissemination, and transmission compared to low titer (lt) virus blood meals. CVV was detected in the saliva of Ae. albopictus (ht: 68%, lt: 24%), Ae. triseriatus (ht: 52%, lt: 7%), Ae. japonicus (ht: 22%, lt: 0%) and Ae. aegypti (ht: 10%; lt: 7%). Culex pipiens and Cx. restuans were not competent for ZIKV or CVV. CONCLUSIONS: This laboratory transmission study provided further understanding of potential ZIKV and CVV transmission cycles with Aedes mosquitoes from Virginia. The ability for these mosquitoes to transmit ZIKV and CVV make them a public health concern and suggest targeted control programs by mosquito and vector abatement districts.


Assuntos
Vírus Bunyamwera/isolamento & purificação , Mosquitos Vetores/virologia , Zika virus/isolamento & purificação , Aedes/virologia , Animais , Bioensaio , Sangue/virologia , Infecções por Bunyaviridae/transmissão , Culex/virologia , Vetores de Doenças , Humanos , Intestinos/virologia , Saliva/virologia , Estados Unidos , Carga Viral , Virginia , Infecção por Zika virus/transmissão
9.
Parasit Vectors ; 13(1): 197, 2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-32299496

RESUMO

BACKGROUND: Larval indices such as the house index (HI), Breteau index (BI) and container index (CI) are widely used to interpret arbovirus vector density in surveillance programmes. However, the use of such data as an alarm signal is rarely considered consciously when planning programmes. The present study aims to investigate the spatial distribution pattern of the infestation of Aedes aegypti, considering the data available in the Ae. aegypti Infestation Index Rapid Survey (LIRAa) for the city of Campina Grande, Paraíba State in Brazil. METHODS: The global and local Moran's indices were used in spatial analysis to measure the effects of spatial dependencies between neighbourhoods, using secondary data related to HI and BI gathered from surveillance service. RESULTS: Our analysis shows that there is a predominance of high rates of mosquito infestation, placing Campina Grande at a near-constant risk of arbovirus outbreaks and epidemics. A highly significant Moran's index value (P < 0.001) was observed, indicating a positive spatial dependency between the neighbourhoods in Campina Grande. Using the Moran mapping and LISA mapping, the autocorrelation patterns of Ae. aegypti infestation rates among neighbourhoods have revealed hotpots that should be considered a priority to preventive actions of the entomological surveillance services. Predominance of high infestation rates and clearer relationships of these between neighbourhoods were observed between the months of May and July, the period with the highest rainfall in the city. CONCLUSIONS: This analysis is an innovative strategy capable of providing detailed information on infestation locations to the relevant public health authorities, which will enable a more efficient allocation of resources, particularly for arbovirus prevention.


Assuntos
Aedes , Controle de Mosquitos , Mosquitos Vetores , Densidade Demográfica , Análise Espacial , Aedes/fisiologia , Aedes/virologia , Animais , Infecções por Arbovirus/prevenção & controle , Infecções por Arbovirus/transmissão , Brasil/epidemiologia , Ecossistema , Modelos Teóricos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Estações do Ano , Urbanização
10.
Aquat Toxicol ; 222: 105474, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32259658

RESUMO

Larval toxicity of ethanolic extract of C. parvula (Ex-Cp) was prominent in the second and the third instars at the maximum lethal dosage of 100 ppm with 98 and 97 % mortality rate respectively. The LC50 and LC90 was displayed at 43 ppm and 88 ppm dosage respectively. Correspondingly, the sub-lethal dosage (65 ppm) of Ex-Cp significantly alters the carboxylesterase (α and ß), GST and CYP450 enzyme level in both III and IV instar larvae in dose-dependent manner. Similarly, the Ex-Cp displayed significant repellent activity (97 %) with a maximum level of protection time (210 min). Photomicrography assay of Ex-Cp (65 ppm) were toxic to dengue larvae as compared to control. The non-target toxicity of Ex-Cp against the beneficial mosquito predators displayed less toxicity at the maximum dosage of 600 ppm as compared to Temephos. Thus the present research delivers the target and non-target toxicity of red algae C. parvula against the dengue mosquito vector.


Assuntos
Aedes/efeitos dos fármacos , Dengue , Repelentes de Insetos/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Extratos Vegetais/farmacologia , Rodófitas/química , Aedes/virologia , Animais , Organismos Aquáticos/efeitos dos fármacos , Carboxilesterase/metabolismo , Dengue/virologia , Relação Dose-Resposta a Droga , Repelentes de Insetos/isolamento & purificação , Repelentes de Insetos/toxicidade , Larva/efeitos dos fármacos , Larva/enzimologia , Dose Letal Mediana , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/toxicidade , Poluentes Químicos da Água/toxicidade
11.
PLoS Negl Trop Dis ; 14(4): e0008217, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32282830

RESUMO

BACKGROUND: The Asian bush mosquito Aedes japonicus is invading Europe and was first discovered in Lelystad, the Netherlands in 2013, where it has established a permanent population. In this study, we investigated the vector competence of Ae. japonicus from the Netherlands for the emerging Zika virus (ZIKV) and zoonotic Usutu virus (USUV). ZIKV causes severe congenital microcephaly and Guillain-Barré syndrome in humans. USUV is closely related to West Nile virus, has recently spread throughout Europe and is causing mass mortality of birds. USUV infection in humans can result in clinical manifestations ranging from mild disease to severe neurological impairments. METHODOLOGY/PRINCIPAL FINDINGS: In our study, field-collected Ae. japonicus females received an infectious blood meal with ZIKV or USUV by droplet feeding. After 14 days at 28°C, 3% of the ZIKV-blood fed mosquitoes and 13% of the USUV-blood fed mosquitoes showed virus-positive saliva, indicating that Ae. japonicus can transmit both viruses. To investigate the effect of the mosquito midgut barrier on virus transmission, female mosquitoes were intrathoracically injected with ZIKV or USUV. Of the injected mosquitoes, 96% (ZIKV) and 88% (USUV) showed virus-positive saliva after 14 days at 28°C. This indicates that ZIKV and USUV can efficiently replicate in Ae. japonicus but that a strong midgut barrier is normally restricting virus dissemination. Small RNA deep sequencing of orally infected mosquitoes confirmed active replication of ZIKV and USUV, as demonstrated by potent small interfering RNA responses against both viruses. Additionally, de novo small RNA assembly revealed the presence of a novel narnavirus in Ae. japonicus. CONCLUSIONS/SIGNIFICANCE: Given that Ae. japonicus can experimentally transmit arthropod-borne viruses (arboviruses) like ZIKV and USUV and is currently expanding its territories, we should consider this mosquito as a potential vector for arboviral diseases in Europe.


Assuntos
Aedes/virologia , Infecções por Flavivirus/transmissão , Mosquitos Vetores/virologia , Infecção por Zika virus/transmissão , Animais , Feminino , Flavivirus , Humanos , Microcefalia/virologia , Países Baixos , Saliva/virologia , Temperatura , Zika virus
12.
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
13.
PLoS Negl Trop Dis ; 14(4): e0008157, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32302295

RESUMO

The successful establishment of the wMel strain of Wolbachia for the control of arbovirus transmission by Aedes aegypti has been proposed and is being implemented in a number of countries. Here we describe the successful establishment of the wMel strain of Wolbachia in four sites in Yogyakarta, Indonesia. We demonstrate that Wolbachia can be successfully introgressed after transient releases of wMel-infected eggs or adult mosquitoes. We demonstrate that the approach is acceptable to communities and that Wolbachia maintains itself in the mosquito population once deployed. Finally, our data show that spreading rates of Wolbachia in the Indonesian setting are slow which may reflect more limited dispersal of Aedes aegypti than seen in other sites such as Cairns, Australia.


Assuntos
Aedes/microbiologia , Mosquitos Vetores/microbiologia , Wolbachia/fisiologia , Aedes/virologia , Animais , Arbovirus , Austrália , Agentes de Controle Biológico , Transmissão de Doença Infecciosa/prevenção & controle , Feminino , Indonésia , Masculino
14.
PLoS Negl Trop Dis ; 14(4): e0008209, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32310960

RESUMO

Dengue, a vector-borne disease spread by Aedes mosquitoes, is a global threat. In the absence of an efficacious dengue vaccine, vector control is the key intervention tool in Singapore. A good understanding of vector habitats is essential to formulate operational strategies. We examined the distribution, long-term trend and seasonality of Aedes data collected during regulatory inspections in residences and public areas from 2008 to 2017. We also studied the seasonality of climate factors to understand their influence on the detection of Aedes-positive containers. The most frequently reported Aedes-positive containers were domestic containers, drains, discarded receptacles, ornamental containers, flower pot plates/trays, plants, gully traps, canvas/plastic sheet, bins, ground puddle, inspection chambers and roof tops/gutters. We found more Ae. aegypti and Ae. albopictus-positive containers per inspection in residences and public areas, respectively. The seasonality of Ae. aegypti-positive containers in residences and public areas coincided with that of mean temperature. However, the seasonality of Ae. albopictus-positive containers lagged by one month compared to that of mean temperature. Our study demonstrates the seasonal fluctuations of Aedes-positive containers in an urban environment. Understanding the distribution and seasonality of Aedes breeding helps to facilitate resource planning and community awareness to moderate dengue transmission.


Assuntos
Aedes/crescimento & desenvolvimento , Aedes/virologia , Distribuição Animal , Meio Ambiente , Estações do Ano , Aedes/classificação , Animais , Dengue/transmissão , Vírus da Dengue/isolamento & purificação , Vírus da Dengue/fisiologia , Habitação , Larva/virologia , Mosquitos Vetores/virologia , Pupa/virologia , Singapura
15.
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
16.
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
17.
PLoS Negl Trop Dis ; 14(3): e0007926, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32155143

RESUMO

The global incidence of arboviral diseases transmitted by Aedes mosquitoes, including dengue, chikungunya, yellow fever, and Zika, has increased dramatically in recent decades. The release of Aedes aegypti carrying the maternally inherited symbiont Wolbachia as an intervention to control arboviruses is being trialled in several countries. However, these efforts are compromised in many endemic regions due to the co-localization of the secondary vector Aedes albopictus, the Asian tiger mosquito. Ae. albopictus has an expanding global distribution following incursions into a number of new territories. To date, only the wMel and wPip strains of Wolbachia have been reported to be transferred into and characterized in this vector. A Wolbachia strain naturally infecting Drosophila simulans, wAu, was selected for transfer into a Malaysian Ae. albopictus line to create a novel triple-strain infection. The newly generated line showed self-compatibility, moderate fitness cost and complete resistance to Zika and dengue infections.


Assuntos
Aedes/microbiologia , Aedes/virologia , Antibiose , Arbovirus/crescimento & desenvolvimento , Wolbachia/crescimento & desenvolvimento , Animais , Infecções por Arbovirus/prevenção & controle , Transmissão de Doença Infecciosa/prevenção & controle , Drosophila/microbiologia , Feminino , Masculino , Mosquitos Vetores/microbiologia , Mosquitos Vetores/virologia , Wolbachia/isolamento & purificação
18.
PLoS Negl Trop Dis ; 14(3): e0008047, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32187187

RESUMO

Since Zika virus (ZIKV) emerged as a global human health threat, numerous studies have pointed to Aedes aegypti as the primary vector due to its high competence and propensity to feed on humans. The majority of vector competence studies have been conducted between 26-28°C, but arboviral extrinsic incubation periods (EIPs), and therefore transmission efficiency, are known to be affected strongly by temperature. To better understand the relationship between ZIKV EIPs and temperature, we evaluated the effect of adult mosquito exposure temperature on ZIKV infection, dissemination, and transmission in Ae. aegypti at four temperatures: 18°C, 21°C, 26°C, and 30°C. Mosquitoes were exposed to viremic mice infected with a 2015 Puerto Rican ZIKV strain, and engorged mosquitoes were sorted into the four temperatures with 80% RH and constant access to 10% sucrose. ZIKV infection, dissemination, and transmission rates were assessed via RT-qPCR from individual mosquito bodies, legs and wings, and saliva, respectively, at three to five time points per temperature from three to 31 days, based on expectations from other flavivirus EIPs. The median time from ZIKV ingestion to transmission (median EIP, EIP50) at each temperature was estimated by fitting a generalized linear mixed model for each temperature. EIP50 ranged from 5.1 days at 30°C to 24.2 days at 21°C. At 26°C, EIP50 was 9.6 days. At 18°C, only 15% transmitted by day 31 so EIP50 could not be estimated. This is among the first studies to characterize the effects of temperature on ZIKV EIP in Ae. aegypti, and the first to do so based on feeding of mosquitoes on a live, viremic host. This information is critical for modeling ZIKV transmission dynamics to understand geographic and seasonal limits of ZIKV risk; it is especially relevant for determining risk in subtropical regions with established Ae. aegypti populations and relatively high rates of return travel from the tropics (e.g. California or Florida), as these regions typically experience cooler temperature ranges than tropical regions.


Assuntos
Aedes/efeitos da radiação , Aedes/virologia , Exposição Ambiental , Mosquitos Vetores/efeitos da radiação , Mosquitos Vetores/virologia , Temperatura , Zika virus/crescimento & desenvolvimento , Estruturas Animais/virologia , Animais , Modelos Animais de Doenças , Transmissão de Doença Infecciosa , Feminino , Camundongos , Modelos Estatísticos , RNA Viral/análise , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo , Infecção por Zika virus/transmissão
19.
PLoS One ; 15(3): e0229668, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32160217

RESUMO

Dengue disease is a major problem for public health surveillance entities in tropical and subtropical regions having a significant impact not only epidemiological but social and economical. There are many factors involved in the dengue transmission process. We can evaluate the importance of these factors through the formulation of mathematical models. However, the majority of the models presented in the literature tend to be overparameterized, with considerable uncertainty levels and excessively complex formulations. We aim to evaluate the structure, complexity, trustworthiness, and suitability of three models, for the transmission of dengue disease, through different strategies. To achieve this goal, we perform structural and practical identifiability, sensitivity and uncertainty analyses to these models. The results showed that the simplest model was the most appropriate and reliable when the only available information to fit them is the cumulative number of reported dengue cases in an endemic municipality of Colombia.


Assuntos
Dengue/transmissão , Aedes/virologia , Animais , Número Básico de Reprodução/estatística & dados numéricos , Colômbia/epidemiologia , Simulação por Computador , Dengue/epidemiologia , Doenças Endêmicas , Fatores Epidemiológicos , Humanos , Conceitos Matemáticos , Modelos Biológicos , Mosquitos Vetores/virologia , Dinâmica Populacional/estatística & dados numéricos , Vigilância em Saúde Pública , Incerteza
20.
PLoS Negl Trop Dis ; 14(3): e0008163, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32203510

RESUMO

Zika virus (ZIKV) is a Flavivirus (Flaviviridae) transmitted to humans mainly by the bite of an infected Aedes mosquitoes. Aedes aegypti is the primary epidemic vector of ZIKV and Ae. albopictus, the secondary one. However, the epidemiological role of both Aedes species in Central Africa where Ae. albopictus was recently introduced is poorly characterized. Field-collected strains of Ae. aegypti and Ae. albopictus from different ecological settings in Central Africa were experimentally infected with a ZIKV strain isolated in West Africa. Mosquitoes were analysed at 14- and 21-days post-exposure. Both Ae. aegypti and Ae. albopictus were able to transmit ZIKV but with higher overall transmission efficiency for Ae. aegypti (57.9%) compared to Ae. albopictus (41.5%). In addition, disseminated infection and transmission rates for both Ae. aegypti and Ae. albopictus varied significantly according to the location where they were sampled from. We conclude that both Ae. aegypti and Ae. albopictus are able to transmit ZIKV and may intervene as active Zika vectors in Central Africa. These findings could contribute to a better understanding of the epidemiological transmission of ZIKV in Central Africa and develop suitable strategy to prevent major ZIKV outbreaks in this region.


Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Infecção por Zika virus/virologia , Zika virus/isolamento & purificação , Aedes/classificação , África Central , Animais , Suscetibilidade a Doenças , Feminino , Mapeamento Geográfico , Mosquitos Vetores/classificação , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/transmissão
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