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1.
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
2.
Artigo em Inglês | MEDLINE | ID: mdl-32049261

RESUMO

Aedes aegypti is associated with epidemic diseases in Brazil, such as urban yellow fever, dengue, and more recently, chikungunya and Zika viruses infections. More information about Ae. aegypti infestation is fundamental to virological surveillance in order to ensure the effectiveness of control measures in use. Thus, the present study aims to identify and compare infestation and infectivity of Ae. aegypti females in Macapa city, Amapa State (Amazon region), Brazil, between the epidemiological weeks 2017/02 and 2018/20. A total number of 303 Ae. aegypti females were collected at 21 fixed collection points, 171 at the 10 collection points in the Marabaixo neighborhood and 132 at the 11 collection points in the Central neighborhood. Among the collected samples, only two were positive for dengue virus, with a 2.08% (2/96 pools) infectivity rate for Marabaixo. The difference between the medians of Ae. aegypti females captured in Central and Marabaixo sites was not statistically significant. The findings indicate similar mosquito infestation levels between the neighborhoods, and a low-level of mosquito infectivity, although dengue virus was found only in Marabaixo. Virological surveillance of Ae. aegypti was important to identify sites of infection and determine possible routes of transmission to enable health surveillance teams to adopt preventive strategies where infected mosquitoes are present and act faster.


Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Animais , Brasil , Febre de Chikungunya/transmissão , Dengue/transmissão , Feminino , Prevalência , Infecção por Zika virus/transmissão
3.
Parasit Vectors ; 13(1): 53, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32033619

RESUMO

BACKGROUND: Aedes-borne diseases such as dengue and chikungunya constitute constant threats globally. In Tanzania, these diseases are transmitted by Aedes aegypti, which is widely distributed in urban areas, but whose ecology remains poorly understood in small towns and rural settings. METHODS: A survey of Ae. aegypti aquatic habitats was conducted in and around Ifakara, a fast-growing town in south-eastern Tanzania. The study area was divided into 200 × 200 m search grids, and habitats containing immature Aedes were characterized. Field-collected Ae. aegypti were tested for susceptibility to common public health insecticides (deltamethrin, permethrin, bendiocarb and pirimiphos-methyl) in the dry and rainy seasons. RESULTS: Of 1515 and 1933 aquatic habitats examined in the dry and rainy seasons, 286 and 283 contained Aedes immatures, respectively (container index, CI: 18.9-14.6%). In the 2315 and 2832 houses visited in the dry and rainy seasons, 114 and 186 houses had at least one Aedes-positive habitat, respectively (house index, HI: 4.9-6.6%). The main habitat types included: (i) used vehicle tires and discarded containers; (ii) flowerpots and clay pots; and (iii) holes made by residents on trunks of coconut trees when harvesting the coconuts. Used tires had highest overall abundance of Ae. aegypti immatures, while coconut tree-holes had highest densities per habitat. Aedes aegypti adults were susceptible to all tested insecticides in both seasons, except bendiocarb, against which resistance was observed in the rainy season. CONCLUSIONS: To our knowledge, this is the first study on ecology and insecticide susceptibility of Ae. aegypti in Ifakara area, and will provide a basis for future studies on its pathogen transmission activities and control. The high infestation levels observed indicate significant risk of Aedes-borne diseases, requiring immediate action to prevent potential outbreaks in the area. While used tires, discarded containers and flowerpots are key habitats for Ae. aegypti, this study also identified coconut harvesting as an important risk factor, and the associated tree-holes as potential targets for Aedes control. Since Ae. aegypti mosquitoes in the area are still susceptible to most insecticides, effective control could be achieved by combining environmental management, preferably involving communities, habitat removal and insecticide spraying.


Assuntos
Aedes , Distribuição Animal , Ecossistema , Inseticidas , Aedes/efeitos dos fármacos , Animais , Febre de Chikungunya/transmissão , Cidades , Doenças Transmissíveis/transmissão , Dengue/transmissão , Insetos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , População Rural , Estações do Ano , Tanzânia
4.
BMC Evol Biol ; 20(1): 31, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32075576

RESUMO

BACKGROUND: In recent years, Ecuador and other South American countries have experienced an increase in arboviral diseases. A rise in dengue infections was followed by introductions of chikungunya and Zika, two viruses never before seen in many of these areas. Furthermore, the latest socioeconomic and political instability in Venezuela and the mass migration of its population into the neighboring countries has given rise to concerns of infectious disease spillover and escalation of arboviral spread in the region. RESULTS: We performed phylogeographic analyses of dengue (DENV) and chikungunya (CHIKV) virus genomes sampled from a surveillance site in Ecuador in 2014-2015, along with genomes from the surrounding countries. Our results revealed at least two introductions of DENV, in 2011 and late 2013, that initially originated from Venezuela and/or Colombia. The introductions were subsequent to increases in the influx of Venezuelan and Colombian citizens into Ecuador, which in 2013 were 343% and 214% higher than in 2009, respectively. However, we show that Venezuela has historically been an important source of DENV dispersal in this region, even before the massive exodus of its population, suggesting already established paths of viral distribution. Like DENV, CHIKV was introduced into Ecuador at multiple time points in 2013-2014, but unlike DENV, these introductions were associated with the Caribbean. Our findings indicated no direct CHIKV connection between Ecuador, Colombia, and Venezuela as of 2015, suggesting that CHIKV was, at this point, not following the paths of DENV spread. CONCLUSION: Our results reveal that Ecuador is vulnerable to arbovirus import from many geographic locations, emphasizing the need of continued surveillance and more diversified prevention strategies. Importantly, increase in human movement along established paths of viral dissemination, combined with regional outbreaks and epidemics, may facilitate viral spread and lead to novel virus introductions. Thus, strengthening infectious disease surveillance and control along migration routes and improving access to healthcare for the vulnerable populations is of utmost importance.


Assuntos
Febre de Chikungunya/epidemiologia , Vírus Chikungunya/classificação , Vírus Chikungunya/genética , Vírus da Dengue/classificação , Vírus da Dengue/genética , Dengue/epidemiologia , Emigração e Imigração/estatística & dados numéricos , Febre de Chikungunya/transmissão , Febre de Chikungunya/virologia , Vírus Chikungunya/isolamento & purificação , Colômbia/epidemiologia , Dengue/transmissão , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Surtos de Doenças , Equador/epidemiologia , Emigração e Imigração/tendências , Genoma Viral , Genótipo , Humanos , Mutação de Sentido Incorreto/fisiologia , Fenótipo , Filogeografia , Análise de Sequência de DNA , América do Sul/epidemiologia , Venezuela/epidemiologia , Zika virus/isolamento & purificação , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
5.
Int J Infect Dis ; 91: 38-43, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31704226

RESUMO

OBJECTIVE: To evaluate the diagnostic performance of the Inbios (Seattle, US) and Euroimmun (Luebeck, Germany) chikungunya virus (CHIKV) IgM enzyme-linked immunoassays (ELISAs). METHODS: We evaluated the tests' accuracy on sera from 372 patients enrolled in an acute febrile illness surveillance study performed in Salvador, Brazil from Sept/2014 to Jul/2016, a period of simultaneous CHIKV, dengue (DENV), and Zika (ZIKV) virus transmission. We assessed the sensitivity on acute and paired convalescent sera from RT-PCR-confirmed CHIKV cases (collected at median one and 19 days post-onset of symptoms, respectively), and the specificity on sera of RT-PCR-confirmed DENV and ZIKV cases, and on negative patients. RESULTS: The Inbios and Euroimmun tests' sensitivities for acute samples were 4.0% and 10.3%, while for convalescent samples they were 92.4% and 96.9%, respectively. Overall, Inbios IgM ELISA specificities for acute and convalescent samples were 97.7% and 90.5%, respectively, and Euroimmun specificities were 88.5% and 83.9%, respectively. CONCLUSIONS: Both tests presented high sensitivity for convalescent samples. However, the Euroimmun test returned more equivocal results and presented a slightly lower specificity, which might result in a higher rate of false positives if the test is used in scenarios of low CHIKV transmission, when the chance of CHIKV infection is lower.


Assuntos
Anticorpos Antivirais/sangue , Febre de Chikungunya/diagnóstico , Vírus Chikungunya/imunologia , Ensaio de Imunoadsorção Enzimática , Imunoglobulina M/sangue , Adolescente , Adulto , Brasil , Febre de Chikungunya/imunologia , Febre de Chikungunya/transmissão , Dengue/transmissão , Vírus da Dengue/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Adulto Jovem , Infecção por Zika virus/transmissão
6.
Annu Rev Entomol ; 65: 313-332, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31594410

RESUMO

Chikungunya virus (CHIKV), a re-emerging mosquito-borne arbovirus, has caused millions of cases of severe, often chronic arthralgia during recent outbreaks. In Africa, circulation in sylvatic, enzootic cycles involves several species of arboreal mosquito vectors that transmit among diverse nonhuman primates and possibly other amplifying hosts. Most disease occurs when CHIKV emerges into a human-amplified cycle involving Aedes aegypti and sometimes Aedes albopictus transmission and extensive spread via travelers. Epidemiologic studies suggest that the transition from enzootic to epidemic cycles begins when people are infected via spillover in forests. However, efficient human amplification likely only ensues far from enzootic habitats where peridomestic vector and human densities are adequate. Recent outbreaks have been enhanced by mutations that adapt CHIKV for more efficient infection of Ae. albopictus, allowing for geographic expansion. However, epistatic interactions, sometimes resulting from founder effects following point-source human introductions, have profound effects on transmission efficiency, making CHIKV emergence somewhat unpredictable.


Assuntos
Aedes/virologia , Febre de Chikungunya/transmissão , Vírus Chikungunya , Mosquitos Vetores/virologia , Animais , Comportamento Animal , Humanos
7.
Artigo em Inglês | MEDLINE | ID: mdl-31847373

RESUMO

Climate change is known to affect Pacific Island nations in a variety of ways. One of them is by increasing the vulnerability of human health induced by various climate change impacts, which pose an additional burden to the already distressed health systems in the region. This paper explores the associations between climate change and human health on the one hand, and outlines some of the health care challenges posed by a changing climate on the other. In particular, it describes the links between climate variations and the emergence of climate-sensitive infectious diseases, such as the mosquito-borne diseases dengue, chikungunya, and Zika. The paper also presents a summary of the key findings of the research initiatives Climate Change and Prevalence Study of ZIKA Virus Diseases in Fiji and the findings from the World Mosquito Program as two examples of public health action in the Pacific region.


Assuntos
Febre de Chikungunya/transmissão , Mudança Climática , Dengue/transmissão , Mosquitos Vetores , Infecção por Zika virus/transmissão , Animais , Doenças Transmissíveis/epidemiologia , Culicidae , Fiji , Humanos , Ilhas do Pacífico , Saúde Pública , Zika virus
8.
Parasit Vectors ; 12(1): 597, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31856896

RESUMO

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


Assuntos
Aedes/genética , Variação Genética , Mosquitos Vetores/genética , Aedes/classificação , Aedes/fisiologia , Animais , Febre de Chikungunya/transmissão , Dengue/transmissão , Genótipo , Humanos , Ilhas , Repetições de Microssatélites , Mosquitos Vetores/classificação , Mosquitos Vetores/fisiologia , Reunião
9.
PLoS Negl Trop Dis ; 13(11): e0007878, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31697681

RESUMO

Chikungunya virus (CHIKV) emerged in Colombia in 2014 into a population presumed fully susceptible. This resulted in a quick and intense spread across Colombia, resulting in an epidemic that affected an estimated 450,000 people. The reported Colombian cases accounted for over 49% of all the cases reported to the PAHO. Eco-environmental factors are known to be associated with the spread of arboviruses such as CHIKV, and likely contribute to the differences in transmission profiles that were observed across several municipalities. To determine the association of eco-environmental factors and CHIKV, the basic reproduction number (R0) in 85 municipalities, which accounted for 65.6% of reported CHIKV cases in Colombia, was estimated. Estimates of R0 ranged from 1 to 9, where over 76% of municipalities had R0 values between 1 and 2. When we looked at the distribution of R0, the cumulative proportions were 20% with R0>2, 14% with R0>3, and 9% with R0>4. Next, we determined that there were different patterns of correlation between environmental and/or ecological variables and R0 when we considered different R0 lower-thresholds. Broadly, we found that temperature-related variables are significantly and positively correlated to R0 regardless of the lower threshold, while other variables like duration of outbreak and size of the urban area are inversely related to R0. Specifically, we conclude that high values of temperature-related variables where R0 > 1 will result in a fast growth of cases in a shorter time period (with faster cessation of outbreak transmission) but will result overall in a fewer total cases compared to outbreak areas (R0 > 1, but classified as lower). Thus, in the absence of vector control, a less explosive outbreak may be more advantageous for the virus in terms of transmission.


Assuntos
Número Básico de Reprodução , Febre de Chikungunya/epidemiologia , Surtos de Doenças , Transmissão de Doença Infecciosa , Tempo (Meteorologia) , Febre de Chikungunya/transmissão , Vírus Chikungunya , Cidades/epidemiologia , Colômbia/epidemiologia , Humanos , Temperatura
11.
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
12.
J Ayub Med Coll Abbottabad ; 31(3): 474-475, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31535534

RESUMO

First Chikungunya outbreak occurred in Karachi, Pakistan in 2016. Chikungunya is transmitted by the Aedes mosquito which is also transmits Dengue fever. The first Dengue fever outbreak of Pakistan also occurred in Karachi in 1994. In the past 23 years the disease has spread to all parts of the country. This is comprehensible as there is a lot of travelling between Karachi and other parts of the country which increases the chances of spread of the virus. Based on the precedent of Dengue fever in Pakistan, if appropriate preventive measures are not taken to control Chikungunya, it will only be a matter of time before it hits other parts of the country. At the same time International Health Regulations has to be practiced with all its zest to avoid introduction of diseases like Zika virus and yellow fever, which are also transmitted by Aedes.


Assuntos
Febre de Chikungunya/epidemiologia , Febre de Chikungunya/transmissão , Dengue/epidemiologia , Epidemias , Aedes , Animais , Febre de Chikungunya/prevenção & controle , Vetores de Doenças , Humanos , Paquistão/epidemiologia
13.
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
14.
Cien Saude Colet ; 24(8): 2983-2992, 2019 Aug 05.
Artigo em Português, Inglês | MEDLINE | ID: mdl-31389545

RESUMO

Aedes aegypti is currently a critical disease agent and is responsible for viruses such as Zika, Chikungunya and Dengue's four serotypes. This mosquito's relevance to the current social body has come to the fore and triggered urgent EcoHealth investigations since this approach aims to articulate different theoretical fields to understand the historical linkages between nature, society and health. Based on an ethnographic premise, this study considered the unequal and unfair conditions that make women's health vulnerable to dengue, analyzing their practices and perceptions about the potential breeding grounds in the public space. A semi-structured interview and participant observation, as well as a field diary, were used to compose the study. The research included the participation of ten women living in the outskirts of Fortaleza, Ceará, Brazil, from January to August 2014. The category "Social inequality, context and practices in the public space" emerged from the content analysis. The narratives revealed that unstable living conditions and evident social inequality might influence in a context permeated by waste, with great potential for dengue's mosquito proliferation.


Assuntos
Febre de Chikungunya/prevenção & controle , Dengue/prevenção & controle , Controle de Mosquitos/métodos , Infecção por Zika virus/prevenção & controle , Adulto , Aedes/virologia , Idoso , Animais , Brasil , Febre de Chikungunya/transmissão , Dengue/transmissão , Feminino , Humanos , Entrevistas como Assunto , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Fatores Socioeconômicos , Adulto Jovem , Infecção por Zika virus/transmissão
15.
Parasit Vectors ; 12(1): 333, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31269965

RESUMO

BACKGROUND: Aedes aegypti and Ae. albopictus are important vectors of infectious diseases, especially those caused by arboviruses such as dengue, chikungunya and Zika. Aedes aegypti is very well adapted to urban environments, whereas Ae. albopictus inhabits more rural settings. Pyrethroid resistance is widespread in these vectors, but limited data exist from the Southwest Pacific Region, especially from Melanesia. While Aedes vector ecology is well documented in Australia, where incursion of Ae. albopictus and pyrethroid resistance have so far been prevented, almost nothing is known about Aedes populations in neighbouring Papua New Guinea (PNG). With pyrethroid resistance documented in parts of Indonesia but not in Australia, it is important to determine the distribution of susceptible and resistant Aedes populations in this region. METHODS: The present study was aimed at assessing Aedes populations for insecticide resistance in Madang and Port Moresby, located on the north and south coasts of PNG, respectively. Mosquitoes were collected using ovitraps and reared in an insectary. Standard WHO bioassays using insecticide-treated filter papers were conducted on a total of 253 Ae. aegypti and 768 Ae. albopictus adult mosquitoes. Subsets of samples from both species (55 Ae. aegypti and 48 Ae. albopictus) were screened for knockdown resistance mutations in the voltage-sensitive sodium channel (Vssc) gene, the target site of pyrethroid insecticides. RESULTS: High levels of resistance against pyrethroids were identified in Ae. aegypti from Madang and Port Moresby. Aedes albopictus exhibited susceptibility to pyrethroids, but moderate levels of resistance to DDT. Mutations associated with pyrethroid resistance were detected in all Ae. aegypti samples screened. Some genotypes found in the present study had been observed previously in Indonesia. No Vssc mutations associated with pyrethroid resistance were found in the Ae. albopictus samples. CONCLUSIONS: To our knowledge, this is the first report of pyrethroid resistance in Ae. aegypti mosquitoes in PNG. Interestingly, usage of insecticides in PNG is low, apart from long-lasting insecticidal nets distributed for malaria control. Further investigations on how these resistant Ae. aegypti mosquito populations arose in PNG and how they are being sustained are warranted.


Assuntos
Aedes/efeitos dos fármacos , Febre de Chikungunya/transmissão , Dengue/transmissão , Resistência a Inseticidas , Mosquitos Vetores/efeitos dos fármacos , Infecção por Zika virus/transmissão , Aedes/virologia , Animais , Arbovirus/fisiologia , Feminino , Inseticidas/farmacologia , Mosquitos Vetores/virologia , Papua Nova Guiné , Piretrinas/farmacologia
16.
Emerg Microbes Infect ; 8(1): 962-972, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31259662

RESUMO

Europe is the world's leading tourism destination and is receiving every year travellers from areas with active arbovirus transmission. There is thus a threat of mosquito-borne virus emergence in Europe due to the presence of the invasive mosquito vector Aedes albopictus. Little attention has been paid about the possible role of indigenous mosquito species as vectors of emerging arboviruses. Here, we assessed the vector competence dynamic of Aedes geniculatus, a European anthropophilic mosquito species, for chikungunya virus (CHIKV) in comparison with an European population of Ae. albopictus. We revealed that Ae. geniculatus is highly susceptible to CHIKV infection and could transmit the virus. By specifically exploring the vector competence dynamic in both mosquito species, we revealed that the cumulative distribution of CHIKV incubation period in Ae. geniculatus was delayed by several days as compared to Ae. albopictus. Our results strengthen the importance of considering indigenous species as potential vectors for emerging arboviruses. They also revealed the importance of considering variation in arbovirus dissemination or transmission dynamics in mosquitoes when performing vector competence assays. We will discuss the implications of our results on a CHIKV outbreak dynamic in a theoretical framework.


Assuntos
Aedes/virologia , Febre de Chikungunya/transmissão , Febre de Chikungunya/virologia , Vírus Chikungunya/isolamento & purificação , Mosquitos Vetores/virologia , Aedes/fisiologia , Animais , Vírus Chikungunya/classificação , Vírus Chikungunya/genética , Europa (Continente) , Feminino , Humanos , Mosquitos Vetores/fisiologia
17.
PLoS Negl Trop Dis ; 13(7): e0007528, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31276467

RESUMO

Extreme weather events affect the development and survival of disease pathogens and vectors. Our aim was to investigate the potential effects of heat waves on the population dynamics of Asian tiger mosquito (Aedes albopictus), which is a major vector of dengue and Zika viruses. We modeled the population abundance of blood-fed mosquito adults based on a mechanistic population model of Ae. albopictus with the consideration of diapause. Using simulated heat wave events derived from a 35-year historical dataset, we assessed how the mosquito population responded to different heat wave characteristics, including the onset day, duration, and the average temperature. Two important observations are made: (1) a heat wave event facilitates the population growth in the early development phase but tends to have an overall inhibitive effect; and (2) two primary factors affecting the development are the unusual onset time of a heat wave and a relatively high temperature over an extended period. We also performed a sensitivity analysis using different heat wave definitions, justifying the robustness of the findings. The study suggests that particular attention should be paid to future heat wave events with an abnormal onset time or a lasting high temperature in order to develop effective strategies to prevent and control Ae. albopictus-borne diseases.


Assuntos
Aedes/fisiologia , Calor Extremo , Mosquitos Vetores/fisiologia , Aedes/virologia , Animais , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/transmissão , Dengue/prevenção & controle , Dengue/transmissão , Mosquitos Vetores/virologia , Dinâmica Populacional , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão
18.
19.
Rev Soc Bras Med Trop ; 52: e20180341, 2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31271613

RESUMO

INTRODUCTION: Areas at risk of transmission of arboviruses have been monitored using ovitraps. This study aimed to evaluate the spatial distribution of Aedes aegypti in vulnerable areas for the transmission of arboviruses and assess the influence of climatic conditions on the infestation of these culicids. METHODS: Ovitraps were installed in Agrestina, Pernambuco, Northeastern Brazil. RESULTS: Overall, 44,936 eggs were collected, and the indexes of infestation varied. Relative humidity was significantly associated with the infestations. CONCLUSIONS: Using ovitraps, entomologic indexes and analysis of climatic factors might be good strategies for monitoring vulnerable areas for the transmission of arboviruses.


Assuntos
Arbovirus , Febre de Chikungunya/prevenção & controle , Dengue/prevenção & controle , Controle de Mosquitos/métodos , Oviposição , Infecção por Zika virus/prevenção & controle , Aedes/fisiologia , Animais , Brasil , Febre de Chikungunya/transmissão , Dengue/transmissão , Humanos , Umidade , Mosquitos Vetores/fisiologia , Chuva , Características de Residência , Estações do Ano , Análise Espacial , Temperatura , Infecção por Zika virus/transmissão
20.
PLoS One ; 14(6): e0217871, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31185030

RESUMO

The emergence of chikungunya virus (CHIKV) has raised serious concerns due to the virus' rapid dissemination into new geographic areas and the clinical features associated with infection. To better understand CHIKV dynamics in Rio de Janeiro, we generated 11 near-complete genomes by means of real-time portable nanopore sequencing of virus isolates obtained directly from clinical samples. To better understand CHIKV dynamics in Rio de Janeiro, we generated 11 near-complete genomes by means of real-time portable nanopore sequencing of virus isolates obtained directly from clinical samples. Our phylogenetic reconstructions indicated the circulation of the East-Central-South-African (ECSA) lineage in Rio de Janeiro. Time-measured phylogenetic analysis combined with CHIKV notified case numbers revealed the ECSA lineage was introduced in Rio de Janeiro around June 2015 (95% Bayesian credible interval: May to July 2015) indicating the virus was circulating unnoticed for 5 months before the first reports of CHIKV autochthonous transmissions in Rio de Janeiro, in November 2015. These findings reinforce that continued genomic surveillance strategies are needed to assist in the monitoring and understanding of arbovirus epidemics, which might help to attenuate public health impact of infectious diseases.


Assuntos
Febre de Chikungunya/genética , Vírus Chikungunya/genética , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Adulto , África/epidemiologia , Brasil/epidemiologia , Febre de Chikungunya/epidemiologia , Febre de Chikungunya/transmissão , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
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