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1.
Sci Total Environ ; 754: 142420, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33254953

RESUMO

Culex mosquitoes are important vectors of West Nile Virus (WNV), St. Louis Encephalitis Virus (SLEV) and Japanese Encephalitis Virus (JEV). Climate change is expected to alter their ability to spread diseases in human populations. Studies examining the influence of climate variability on Culex mosquitoes in South East Asia are scarce. We examined the influence of climate variability on reported Culex mosquito larval habitats from 2009 to 2018 in Singapore. We analysed the non-linear immediate and lagged weather dependence of Culex habitats over 5 weeks in negative binomial regression models using nationally representative data. We adjusted for the effects of long-term trend, seasonality, public holidays and autocorrelation. There were 41,170 reported Culex larval habitats over the study period. Non-residential premises were associated with more reports of habitats compared to residential premises [Rate Ratio (RR): 113.9, 95% CI: 110.9, 116.9]. Larvae in more than 90% of these habitats were entomologically identified as Culex quinquefasciatus. In residences, every 10 mm increase in rainfall above a 90 mm threshold was associated with a 10.1% [Incidence Rate Ratio (IRR): 0.899, 95% CI: 0.836, 0.968] cumulative decline in larval habitats. Public holidays were not significantly included in the model analysing larval habitats in residences. In non-residences, a 1 °C increase in the ambient air temperature with respect to the mean was associated with a 36.0% (IRR: 1.360, 95% CI: 1.057, 1.749) cumulative increase in Culex larval habitats. Public holidays were associated with a decline in Culex larval habitats in the same week. Our study provides evidence of how ambient air temperature and rainfall variability influences the abundance of Culex mosquito larval habitats. Our findings support the utility of using weather data in predictive models to inform the timing of vector control measures aimed at reducing the risk of WNV and other Culex-borne flavivirus transmission in urban areas.


Assuntos
Culex , Flavivirus , Vírus do Nilo Ocidental , Animais , Humanos , Mosquitos Vetores , Singapura/epidemiologia , Temperatura
2.
Rev Soc Bras Med Trop ; 54: e00922020, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33338107

RESUMO

INTRODUCTION: Despite their widespread usage, synthetic insecticides and larvicides are harmful for controlling disease-causing mosquitoes owing to the development of resistance. The leaves of Eugenia astringens, Myrrhinium atropurpureum, and Neomitranthes obscura were collected from Marambaia and Grumari restingas. The safety and larvicidal efficacy of their extracts were tested against Aedes (Stegomyia) aegypti L. and Simulium (Chirostilbia) pertinax Kollar. METHODS: The dry leaves were subjected to static maceration extraction using 90% methanol. A. aegypti and S. pertinax larvae were exposed to 7.5, 12.5, and 25.0 µL/mL of the extracts (n= 30). The larvicidal activity after 24 h and 48 h, and the mortality, were determined. The median lethal concentration (CL50) was estimated by a Finney's probit model. RESULTS: M. atropurpureum and E. astringens extracts exhibited the strongest larvicidal effects against A. aegypti. M. atropurpureum extracts (25 µL/mL) caused mortalities of over 50% and 100% after 24 h and 48 h, respectively (CL50 = 11.10 and 9.68 ppm, respectively). E. astringens extracts (25 µL/mL) caused mortalities of 50% and 63.33% after 24 h and 48 h, respectively. High concentrations of N. obscura extracts induced a maximum mortality of 46.66% in A. aegypti larvae after 48 h (CL50= 25 ppm). The larvae of S. pertinax showed 100% mortality following exposure to all the plant extracts at all the tested concentrations after 24 h. CONCLUSIONS: The extracts of M. atropurpuerum exhibited the strongest larvicidal activity against A. aegypti. The larvae of S. pertinax were sensitive to all the extracts at all the tested concentrations.


Assuntos
Aedes , Anopheles , Culex , Inseticidas , Myrtaceae , Simuliidae , Animais , Inseticidas/farmacologia , Larva , Extratos Vegetais/farmacologia , Folhas de Planta
3.
PLoS One ; 15(10): e0227239, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33064724

RESUMO

Species of the genus Flavivirus are widespread in Brazil and are a major public health concern. The country's largest city, São Paulo, is in a highly urbanized area with a few forest fragments which are commonly used for recreation. These can be considered to present a potential risk of flavivirus transmission to humans as they are home simultaneously to vertebrate hosts and mosquitoes that are potential flavivirus vectors. The aim of this study was to conduct flavivirus surveillance in field-collected mosquitoes in the Capivari-Monos Environmental Protection Area (EPA) and identify the flavivirus species by sequence analysis in flavivirus IFA-positive pools. Monthly mosquito collections were carried out from March 2016 to April 2017 with CO2-baited CDC light traps. Specimens were identified morphologically and grouped in pools of up to 10 individuals according to their taxonomic category. A total of 260 pools of non-engorged females were inoculated into C6/36 cell culture, and the cell suspensions were analyzed by indirect immunofluorescence assay (IFA) after the incubation period. IFA-positive pools were tested by qRT-PCR with genus-specific primers targeting the flavivirus NS5 gene to confirm IFA-positive results and sequenced to identify the species. Anopheles cruzii (19.5%) and Wyeomyia confusa (15.3%) were the most frequent vector species collected. IFA was positive for flaviviruses in 2.3% (6/260) of the sample pools. This was confirmed by qRT-PCR in five pools (83.3%). All five flavivirus-positive pools were successfully sequenced and the species identified. DENV serotype 2 (DENV-2) was detected in Culex spp. and Culex vaxus pools, while ZIKV was identified in An. cruzii, Limatus durhamii and Wy. confusa pools. To the best of our knowledge, detection of flavivirus species of medical importance has never previously been reported in these species of wild-caught mosquitoes. The finding of DENV-2 and ZIKV circulating in wild mosquitoes suggests the existence of an enzootic cycle in the area. In-depth studies of DENV-2 and ZIKV, including investigation of mosquito infection, vector competence and infection in sylvatic hosts, are needed to shed light on the transmission dynamics of these important viruses and the potential risk of future outbreaks of DENV-2 and ZIKV infections in the region.


Assuntos
Vírus da Dengue/isolamento & purificação , Mosquitos Vetores/virologia , Proteínas não Estruturais Virais/genética , Zika virus/isolamento & purificação , Animais , Anopheles/virologia , Brasil/epidemiologia , Culex/virologia , Vírus da Dengue/genética , Feminino , Vigilância da População , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Meio Selvagem , Zika virus/genética
4.
Zootaxa ; 4772(1): zootaxa.4772.1.2, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-33055623

RESUMO

Mosquitoes (Diptera: Culicidae) are insects capable of transmitting various disease agents. They have a wide geographical range, with a higher diversity and distribution in the tropical and subtropical regions. In Romania, data on mosquito distribution are available mostly from the older literature and published in local journals; hence, it is inaccessible to the international scientific community. The aim of this review was to gather all the published data on mosquitoes in Romania by performing a comprehensive literature search, to create a publicly available georeferenced database for the distribution of mosquitoes and generate distribution maps to identify gaps in the knowledge of mosquito diversity and distribution in the country. The resultant database includes 1,509 unique records for 51 mosquito species representing seven genera: Aedes, Anopheles, Culex, Culiseta, Coquillettidia, Orthopodomyia and Uranotaenia. Knowledge of mosquito distributions is important for understanding the risks of mosquito-borne pathogens present in Romania, a country with high endemicity for various diseases, such as West Nile fever and dirofilariasis. The database also revealed important knowledge gaps, including the lack of data for the Carpathian Arch and the central part of the historical regions of Moldova and Oltenia. The gaps become more evident, as the presence and diversity of the vectors have not been studied in many areas where diseases caused by mosquito-borne pathogens are present. In conclusion, despite the numerous georeferenced records, large areas of Romania remain unexplored for the mosquito species composition, abundance and phenology. This review is a "call for action" for implementing active surveillance in the country.


Assuntos
Anopheles , Culex , Animais , Mosquitos Vetores , Romênia
5.
Zootaxa ; 4858(4): zootaxa.4858.4.1, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33056210

RESUMO

Species of Culex (Diptera: Culicidae) belonging to the subgenus Culiciomyia were collected in partially logged areas and in surrounding pristine forest (Talangaye Forest) in the Nguti Subdivision in the South-West Region of Cameroon. Mosquitoes were collected mainly by sweep netting through forest floor vegetation. Morphological species identification of African Culiciomyia relies almost exclusively on the structure of the male genitalia and the shapes of comb scales on the maxillary palpi of males. Other features of males and the habitus of females are largely indistinguishable between the species of this subgenus. In total, seven currently described species and three new species were collected in the forest. The males of the three new species are described and named as Culex apicopilosus Cornel Mayi, sp. n., Culex lanzaroi Cornel Mayi, sp. n. and Culex pseudosubaequalis Cornel Mayi, sp. n. More detailed descriptions of males of the other currently known species that were collected in the Talangaye Forest and pictorial keys to the males of all Afrotropical species of Culiciomyia, including the new species, are provided.


Assuntos
Culex , Culicidae , Animais , Camarões , Feminino , Florestas , Masculino
6.
PLoS Pathog ; 16(8): e1008836, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866212

RESUMO

Anthrax is a major zoonotic disease of wildlife, and in places like West Africa, it can be caused by Bacillus anthracis in arid nonsylvatic savannahs, and by B. cereus biovar anthracis (Bcbva) in sylvatic rainforests. Bcbva-caused anthrax has been implicated in as much as 38% of mortality in rainforest ecosystems, where insects can enhance the transmission of anthrax-causing bacteria. While anthrax is well-characterized in mammals, its transmission by insects points to an unidentified anthrax-resistance mechanism in its vectors. In mammals, a secreted anthrax toxin component, 83 kDa Protective Antigen (PA83), binds to cell-surface receptors and is cleaved by furin into an evolutionary-conserved PA20 and a pore-forming PA63 subunits. We show that PA20 increases the resistance of Drosophila flies and Culex mosquitoes to bacterial challenges, without directly affecting the bacterial growth. We further show that the PA83 loop known to be cleaved by furin to release PA20 from PA63 is, in part, responsible for the PA20-mediated protection. We found that PA20 binds directly to the Toll activating peptidoglycan-recognition protein-SA (PGRP-SA) and that the Toll/NF-κB pathway is necessary for the PA20-mediated protection of infected flies. This effect of PA20 on innate immunity may also exist in mammals: we show that PA20 binds to human PGRP-SA ortholog. Moreover, the constitutive activity of Imd/NF-κB pathway in MAPKK Dsor1 mutant flies is sufficient to confer the protection from bacterial infections in a manner that is independent of PA20 treatment. Lastly, Clostridium septicum alpha toxin protects flies from anthrax-causing bacteria, showing that other pathogens may help insects resist anthrax. The mechanism of anthrax resistance in insects has direct implications on insect-mediated anthrax transmission for wildlife management, and with potential for applications, such as reducing the sensitivity of pollinating insects to bacterial pathogens.


Assuntos
Vacinas contra Antraz/administração & dosagem , Antraz/tratamento farmacológico , Antígenos de Bactérias/administração & dosagem , Bacillus anthracis/efeitos dos fármacos , Toxinas Bacterianas/administração & dosagem , Drosophila melanogaster/crescimento & desenvolvimento , Mosquitos Vetores/microbiologia , Substâncias Protetoras/administração & dosagem , Animais , Antraz/microbiologia , Culex , Drosophila melanogaster/imunologia , Drosophila melanogaster/microbiologia , Feminino , Masculino
7.
PLoS One ; 15(9): e0239636, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32976497

RESUMO

Animals with complex life cycles have traits related to oviposition and juvenile survival that can respond to environmental factors in similar or dissimilar ways. We examined the preference-performance hypothesis (PPH), which states that females lacking parental care select juvenile habitats that maximize fitness, for two ubiquitous mosquito species, Aedes albopictus and Culex quinquefasciatus. Specifically, we examined if environmental factors known to affect larval abundance patterns in the field played a role in the PPH for these species. We first identified important environmental factors from a field survey that predicted larvae across different spatial scales. We then performed two experiments, the first testing the independent responses of oviposition and larval survival to these environmental factors, followed by a combined experiment where initial oviposition decisions were allowed to affect larval life history measures. We used path analysis for this last experiment to determine important links among factors in explaining egg numbers, larval mass, development time, and survival. For separate trials, Aedes albopictus displayed congruence between oviposition and larval survival, however C. quinquefasciatus did not. For the combined experiment path analysis suggested neither species completely fit predictions of the PPH, with density dependent effects of initial egg number on juvenile performance in A. albopictus. For these species the consequences of female oviposition choices on larval performance do not appear to fit expectations of the PPH.


Assuntos
Adaptação Fisiológica , Comportamento Animal , Mosquitos Vetores/fisiologia , Oviposição , Aedes/fisiologia , Animais , Culex/fisiologia , Ecossistema , Feminino , Larva/fisiologia , Especificidade da Espécie
8.
Exp Parasitol ; 218: 107988, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32890471

RESUMO

In the present work, we synthesized silver nanoparticles supported by rice husk by hydrothermal treatment, as-synthesized silver nanoparticles rice husk (AgNPs-RH) bio-composite mixed with potter clay thoroughly, molded, dried into a disc-shaped before firing and applying as a point of use larvicidal agent. As designed, porous terracotta disc (PTD) infused with AgNPs-RH-biocomposite were characterized by UV spectrophotometer, Fourier-transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction analysis and energy-dispersive X-ray spectroscopy. The amount of silver ions released from the PTD was also found to be within the prescribed limit of 0.1 ppm-level. Later we dropped the PTD and tested its larvicidal activity against the IVth instar larva stage of Aedes, Anopheles and Culex species. We found 100% larvicidal mortality in 24 h of exposure to the designed PTD and the amount of silver released from the porous disc was found to be 0.0343 ppm. Further from the histopathological studies of dead larvae revealed that the silver ions from the PTD have substantially damaged the exoskeleton of larvae.


Assuntos
Aedes , Anopheles , Culex , Nanopartículas Metálicas/normas , Controle de Mosquitos/instrumentação , Animais , Ecossistema , Química Verde , Larva , Nanopartículas Metálicas/economia , Nanopartículas Metálicas/provisão & distribução , Microscopia Eletrônica de Transmissão , Controle de Mosquitos/economia , Oryza , Prata , Espectrometria por Raios X , Espectrofotometria Atômica , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
9.
Rev Prat ; 70(3): 333-335, 2020 Mar.
Artigo em Francês | MEDLINE | ID: mdl-32877072

RESUMO

West nile virus infection: an emerging arbovirosis in france and europe. West Nile virus is a mosquito-borne flavivirus, transmitted to humans by mosquitoes of the genus Culex, from an avian reservoir. Humans are accidental hosts and there is no report of human-to-human transmission, except via blood transfusion or organ transplantation. In 2018, Europe experienced the largest outbreak of West Nile virus infection ever. In France, 27 cases were identified including 7 neuro invasive forms. This infection is asymptomatic in most cases but may also manifest as an isolated fever or flu-like syndrome. In about 1% of cases, neuro-invasive forms with meningitis, meningoencephalitis or flaccid paralysis can be observed. There is no specific treatment for this viral infection. Prevention is based on the prevention of mosquito bites, but also on enhanced epidemiological surveillance during the period of circulation of the virus in Europe (from spring to autumn).


Assuntos
Culex , Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Animais , Doenças Transmissíveis Emergentes , Europa (Continente)/epidemiologia , França/epidemiologia , Humanos , Febre do Nilo Ocidental/epidemiologia
10.
Proc Biol Sci ; 287(1932): 20201065, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-32752986

RESUMO

Temperature is widely known to influence the spatio-temporal dynamics of vector-borne disease transmission, particularly as temperatures vary across critical thermal thresholds. When temperature conditions exhibit such 'transcritical variation', abrupt spatial or temporal discontinuities may result, generating sharp geographical or seasonal boundaries in transmission. Here, we develop a spatio-temporal machine learning algorithm to examine the implications of transcritical variation for West Nile virus (WNV) transmission in the Los Angeles metropolitan area (LA). Analysing a large vector and WNV surveillance dataset spanning 2006-2016, we found that mean temperatures in the previous month strongly predicted the probability of WNV presence in pools of Culex quinquefasciatus mosquitoes, forming distinctive inhibitory (10.0-21.0°C) and favourable (22.7-30.2°C) mean temperature ranges that bound a narrow 1.7°C transitional zone (21-22.7°C). Temperatures during the most intense months of WNV transmission (August/September) were more strongly associated with infection probability in Cx. quinquefasciatus pools in coastal LA, where temperature variation more frequently traversed the narrow transitional temperature range compared to warmer inland locations. This contributed to a pronounced expansion in the geographical distribution of human cases near the coast during warmer-than-average periods. Our findings suggest that transcritical variation may influence the sensitivity of transmission to climate warming, and that especially vulnerable locations may occur where present climatic fluctuations traverse critical temperature thresholds.


Assuntos
Temperatura , Febre do Nilo Ocidental/transmissão , Vírus do Nilo Ocidental , Animais , California , Culex , Culicidae , Geografia , Humanos , Los Angeles/epidemiologia , Mosquitos Vetores , Febre do Nilo Ocidental/epidemiologia
11.
Environ Res ; 188: 109837, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32798954

RESUMO

Changes in environmental conditions, whether related or not to human activities, are continuously modifying the geographic distribution of vectors, which in turn affects the dynamics and distribution of vector-borne infectious diseases. Determining the main ecological drivers of vector distribution and how predicted changes in these drivers may alter their future distributions is therefore of major importance. However, the drivers of vector populations are largely specific to each vector species and region. Here, we identify the most important human-activity-related and bioclimatic predictors affecting the current distribution and habitat suitability of the mosquito Culex pipiens and potential future changes in its distribution in Spain. We determined the niche of occurrence (NOO) of the species, which considers only those areas lying within the range of suitable environmental conditions using presence data. Although almost ubiquitous, the distribution of Cx. pipiens is mostly explained by elevation and the degree of urbanization but also, to a lesser extent, by mean temperatures during the wettest season and temperature seasonality. The combination of these predictors highlights the existence of a heterogeneous pattern of habitat suitability, with most suitable areas located in the southern and northeastern coastal areas of Spain, and unsuitable areas located at higher altitude and in colder regions. Future climatic predictions indicate a net decrease in distribution of up to 29.55%, probably due to warming and greater temperature oscillations. Despite these predicted changes in vector distribution, their effects on the incidence of infectious diseases are, however, difficult to forecast since different processes such as local adaptation to temperature, vector-pathogen interactions, and human-derived changes in landscape may play important roles in shaping the future dynamics of pathogen transmission.


Assuntos
Culex , Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Animais , Ecossistema , Humanos , Mosquitos Vetores , Espanha , Febre do Nilo Ocidental/epidemiologia
12.
PLoS One ; 15(8): e0236920, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32745085

RESUMO

BACKGROUND: Twenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial. METHODS: We carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations. RESULTS: Eight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively. CONCLUSION: The entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.


Assuntos
Anopheles , Resistência a Inseticidas/genética , Malária Falciparum/transmissão , Mosquitos Vetores/genética , Animais , Anopheles/classificação , Anopheles/genética , Anopheles/parasitologia , Burkina Faso/epidemiologia , Culex/classificação , Culex/genética , Culex/parasitologia , Culicidae/classificação , Culicidae/genética , Culicidae/parasitologia , Ecologia , Genótipo , Humanos , Malária Falciparum/prevenção & controle , Controle de Mosquitos/métodos , Controle de Mosquitos/organização & administração , Mosquitos Vetores/classificação , Mosquitos Vetores/parasitologia , Plasmodium falciparum/isolamento & purificação , Estações do Ano
13.
PLoS Negl Trop Dis ; 14(8): e0008605, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797109

RESUMO

In human communities inhabiting areas-such as West Bengal- India-where perpetuate the pre-imago & adult developmental stages of mosquitoes; many infectious diseases are still diagnosed such as Dengue, Malaria and Acute Encephalitis Syndrome. The control of the aquatic developmental stages is one of the easiest way to prevent the emergence of adults-the blood feeding adult females being thus prevented to sample their blood meal and to lay their eggs in the aquatic milieu where develop the aquatic pre-imaginal developmental stages. Moreover, reducing the adult population size also the probability of for the blood feeding adult female mosquitoes to act as hosts and vectors of the arboviruses such as dengue virus & Japanese encephalitis virus as well as of Plasmodium. Several environmental factors including water quality parameters are responsible for the selection of oviposition sites by the female mosquitoes. In our study, larval densities of three important mosquitoes (Aedes/A. albopictus, Anopheles/An. stephensi and Culex/C. vishnui) were measured and water qualities of their habitat i.e. pH, Specific Conductance, Dissolved Oxygen, Chemical Oxygen Demand, Total alkalinity (Talk), Hardness, Nitrate nitrogen and Ammonia nitrogen were analyzed in 2017 and 2018 in many districts of West Bengal where humans beings are suffering from arboviruses and /or malaria. Whereas we have found positive correlation of density of C. vishnui and A. albopictus with the water factors except Chemical Oxygen Demand (COD) and Talk, for An. stephensi all these factors except pH, COD and Talk have positive correlation. Hardness of the water shows positive correlation with the density of An. stephensi and C. vishnui but negative correlation with density of A. albopictus. Contour plot analysis demonstrates that occurrence of each mosquito species lies in between specific range of water factors. Inter- correlation analysis revealed that mosquitoes were negatively correlated with each other. A positive correlation of the water quality parameters and larval density, over two successive years, was also noticed. In conclusion, the increasing level of pollution due to industrial and other irresponsible waste management system which changes the water quality parameters may also influence mosquito population.


Assuntos
Ecossistema , Controle de Mosquitos , Mosquitos Vetores/fisiologia , Aedes/fisiologia , Animais , Anopheles/fisiologia , Arbovirus , Culex/fisiologia , Dengue/transmissão , Vírus da Encefalite Japonesa (Espécie) , Encefalite Japonesa/transmissão , Feminino , Humanos , Concentração de Íons de Hidrogênio , Índia , Larva , Modelos Logísticos , Malária/transmissão , Mosquitos Vetores/parasitologia , Mosquitos Vetores/virologia , Análise Multivariada , Densidade Demográfica , Água
14.
PLoS Negl Trop Dis ; 14(8): e0008574, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32853274

RESUMO

BACKGROUND: Shifts have occurred in the epidemiological characteristics of Japanese encephalitis (JE), extending from the molecular level to the population level. The aim of this study was to investigate the seroprevalence of JE neutralizing antibodies in healthy populations from different age groups in Zhejiang Province, and to conduct mosquito monitoring to evaluate the infection rate of Japanese encephalitis virus (JEV) among vectors, as well as the molecular characteristics of the E gene of isolated JEV strains. METHODOLOGY/PRINCIPAL FINDINGS: A total of 1190 sera samples were screened by a microseroneutralization test, including 429 infants (28d-11m) and 761 participants (2y-82y). For those under 1 year old, the geometric mean titers (GMTs) of the JE neutralizing antibody was 9.49 at birth and significantly declined as the age of month increased (r = -0.225, P<0.001). For those above 1-year old, seropositive proportions were higher in subjects aged 1-3 years old as well as ≥25 years old (65%-75%), and relatively lower in subjects aged between 4-25 years old (22%-55%). Four or more years after the 2nd dose of JEV-L (first dose administered at 8 months and the second at 2 years of age), the seropositive proportion decreased to 32.5%, and GMTs decreased to 8.08. A total of 87,201 mosquitoes were collected from livestock sheds in 6 surveillance sites during 2015-2018, from which 139 E gene sequences were successfully amplified. The annual infection rate according to bias-corrected maximum likelihood estimation of JEV in Culex tritaeniorhynchus was 1.56, 2.36, 5.65 and 1.77 per 1000, respectively. JEV strains isolated during 2015-2018 all belonged to Genotype I. The E gene of amplified 139 samples differed from the JEV-L vaccine strain at fourteen amino acid residues, including the eight key residues related to virulence and virus attenuation. No divergence was observed at the sites related to antigenicity. CONCLUSIONS/SIGNIFICANCE: Zhejiang Province was at a high risk of JE exposure due to relatively lower neutralizing antibody levels among the younger-aged population and higher infection rates of JEV in mosquitoes. Continuous, timely and full coverage of JE vaccination are essential, as well as the separation of human living areas and livestock shed areas. In addition, annual mosquito surveillance and periodic antibody level monitoring are important for providing evidence for improvement in JE vaccines and immunization schedules.


Assuntos
Vírus da Encefalite Japonesa (Espécie)/genética , Encefalite Japonesa/epidemiologia , Encefalite Japonesa/virologia , Epidemiologia Molecular , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Anticorpos Neutralizantes , Criança , Pré-Escolar , China/epidemiologia , Estudos Transversais , Culex/virologia , Culicidae/virologia , Vírus da Encefalite Japonesa (Espécie)/classificação , Vírus da Encefalite Japonesa (Espécie)/imunologia , Vírus da Encefalite Japonesa (Espécie)/isolamento & purificação , Genes Virais/genética , Humanos , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Estudos Soroepidemiológicos , Adulto Jovem
15.
Environ Sci Pollut Res Int ; 27(34): 43103-43116, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32725570

RESUMO

Pest insects causing damage to cultivable crops and food products by feeding, fecundity, and parasitizing livestock, also being a nuisance to human health. In consideration with human health, the World Health Organization reports that more than 50% of the world's population is presently at risk from mosquito-borne diseases. Mosquitoes are primary vectors for major dreadful diseases such as yellow fever, malaria, and dengue fever, which infect millions of human beings all over the world and kill millions of peoples every year. The present research work was carried out to evaluate the antifeedant, larvicidal, pupicidal, larval, and pupal duration activity of Leonotis nepetifolia-mediated silver nanoparticles (AgNPs) against Spodoptera litura, Helicoverpa armigera, Aedes aegypti, and Culex quinquefasciatus. Biosynthesized AgNPs were characterized through various techniques such as UV-Vis spectrometer, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. The AgNPs showed potential antifeedant activity of 78.77% and 82.16% against the larvae of S. litura and H. armigera, respectively. The maximum larval mortality rate (78.49% and 72.70%) and maximum pupal mortality rate (84.66% and 77.44%) were observed against S. litura and H. armigera. Mosquito larvae were tested with biosynthesized AgNPs, and recorded LC50 values were 47.44 ppm and 35.48 ppm on A. aegypti and C. quinquefasciatus, respectively. The histological examinations showed that the acceleration of the nanomaterial caused severe tissue damage in the epithelial and goblet cells in the larval midgut region of S. litura, H. armigera, A. aegypti, and C. quinquefasciatus. Biosynthesis of silver nanoparticles using L. nepetifolia is an ideal eco-friendly approach for the management of insect pests. Graphical abstract.


Assuntos
Aedes , Anopheles , Culex , Inseticidas , Lamiaceae , Nanopartículas Metálicas , Animais , Larva , Nanopartículas Metálicas/toxicidade , Mosquitos Vetores , Extratos Vegetais , Folhas de Planta , Prata , Spodoptera
16.
Environ Sci Pollut Res Int ; 27(33): 41568-41576, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32691320

RESUMO

To seek new mosquito control agents while avoiding the environmental impacts and toxicity hazards of conventional pesticides, the essential oil of Dysphania ambrosioides was obtained by hydrodistillation and analysed using GC-FID and GC-MS. The compounds 1-methyl-4-(1-methylethyl)-2,3-dioxabicyclo[2.2.2]oct-5-ene (cis-ascaridole), 1-methyl-4-(1-methylethyl) benzene (р-cymene), and 1-isopropyl-4-methyl-1,3-cyclohexadiene (p-mentha-1,3-diene also known as α-terpinene) were identified as the major components. The EO and the major fractions showed remarkable mosquitocidal activity against third instar larvae and adults of Culex quinquefasciatus Say. The oil and fractions were assayed at 3.125, 6.25, 12.5, 25, and 50 µl/l. Mortality was time- and dose-dependent. At 24 h post-exposure at an assayed concentration of 50 µl/l, the larval and adult mortalities ranged between 80.11-100% and 91.22-100%, respectively. Strong larvicidal and adulticidal activities were recorded in the cases of the crude oil and cis-ascaridole. The LC50 values after 24 h of treatment ranged between 6.2-20.1 µl/l and 5.1-13.9 µl/l against larvae and adults, respectively. The corrected percentage mortalities increased over time with the tested plant oil and the major fractions relative to the control. The time required to achieve 50% mortality (LT50) decreased remarkably with all treatments. The tested EO and major fractions effectively inhibited larval acetylcholinesterase activity with IC50 values ranging from 8.44 to 64.80 mM compared with 2.08 × 10-3 mM for the reference standard, methomy. The results indicate the potential of developing natural mosquitocides against C. quinquefasciatus based on the tested EO and its major fractions. Graphical abstract.


Assuntos
Aedes , Culex , Inseticidas , Óleos Voláteis , Animais , Larva , Controle de Mosquitos , Óleos Voláteis/farmacologia , Extratos Vegetais , Folhas de Planta
17.
Am J Trop Med Hyg ; 103(3): 1234-1240, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32700679

RESUMO

Mosquito-borne flaviviruses are emerging pathogens of an increasing global public health concern because of their rapid increase in geographical range and the impact of climate change. Japanese encephalitis virus (JEV) and West Nile virus (WNV) are of concern because of the risk of reemergence and introduction by migratory birds. In Singapore, human WNV infection has never been reported and human JEV infection is rare. Four sentinel vector surveillance sites were established in Singapore to understand the potential risk posed by these viruses. Surveillance was carried out from August 2011 to December 2012 at Pulau Ubin, from March 2011 to March 2013 at an Avian Sanctuary (AS), from December 2010 from October 2012 at Murai Farmway, and from December 2010 to December 2013 at a nature reserve. The present study revealed active JEV transmission in Singapore through the detection of JEV genotype II in Culex tritaeniorhynchus collected from an Avian Sanctuary. Culex flavivirus (CxFV), similar to the Quang Binh virus isolated from Cx. tritaeniorhynchus in Vietnam and CxFV-LSFlaviV-A20-09 virus isolated in China, was also detected in Culex spp. (vishnui subgroup). No WNV was detected. This study demonstrates the important role that surveillance plays in public health and strongly suggests the circulation of JEV among wildlife in Singapore, despite the absence of reported human cases. A One Health approach involving surveillance, the collaboration between public health and wildlife managers, and control of mosquito populations remains the key measures in risk mitigation of JEV transmission in the enzootic cycle between birds and mosquitoes.


Assuntos
Culex/virologia , Vírus da Encefalite Japonesa (Espécie)/isolamento & purificação , Encefalite Japonesa/epidemiologia , Mosquitos Vetores/virologia , Animais , Vírus da Encefalite Japonesa (Espécie)/genética , Encefalite Japonesa/virologia , Monitoramento Epidemiológico , Feminino , Genótipo , Geografia , Humanos , Singapura/epidemiologia
18.
Sci Rep ; 10(1): 11915, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681089

RESUMO

This research addresses public speculation that SARS-CoV-2 might be transmitted by mosquitoes. The World Health Organization has stated "To date there has been no information nor evidence to suggest that the new coronavirus could be transmitted by mosquitoes". Here we provide the first experimental data to investigate the capacity of SARS-CoV-2 to infect and be transmitted by mosquitoes. Three widely distributed species of mosquito; Aedes aegypti, Ae. albopictus and Culex quinquefasciatus, representing the two most significant genera of arbovirus vectors that infect people, were tested. We demonstrate that even under extreme conditions, SARS-CoV-2 virus is unable to replicate in these mosquitoes and therefore cannot be transmitted to people even in the unlikely event that a mosquito fed upon a viremic host.


Assuntos
Betacoronavirus/fisiologia , Culicidae/virologia , Aedes/virologia , Animais , Betacoronavirus/isolamento & purificação , Chlorocebus aethiops , Culex/virologia , Insetos Vetores/virologia , Células Vero
19.
PLoS One ; 15(7): e0228835, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649665

RESUMO

The mosquito Culex erythrothorax Dyar is a West Nile virus (WNV) vector that breeds in wetlands with emergent vegetation. Urbanization and recreational activities near wetlands place humans, birds and mosquitoes in close proximity, increasing the risk of WNV transmission. Adult Cx. erythrothorax abundance peaked in a wetland bordering the San Francisco Bay of California (USA) during the first 3 hours after sunset (5527 ± 4070 mosquitoes / trap night) while peak adult Culex tarsalis Coquillett abundance occurred during the subsequent 3 h period (83 ± 30 Cx. tarsalis). When insecticide resistance was assessed using bottle bioassay, Cx. erythrothorax was highly sensitive to permethrin, naled, and etofenprox insecticides compared to a strain of Culex pipiens that is susceptible to insecticides (LC50 = 0.35, 0.71, and 4.1 µg/bottle, respectively). The Cx. erythrothorax were 2.8-fold more resistant to resmethrin, however, the LC50 value was low (0.68 µg/bottle). Piperonyl butoxide increased the toxicity of permethrin (0.5 µg/bottle) and reduced knock down time, but a higher permethrin concentration (2.0 µg/bottle) did not have similar effects. Bulk mixed-function oxidase, alpha-esterase, or beta-esterase activities in mosquito homogenates were higher in Cx. erythrothorax relative to the Cx. pipiens susceptible strain. There was no difference in the activity of glutathione S-transferase between the two mosquito species and insensitive acetylcholine esterase was not detected. Larvicides that were applied to the site had limited impact on reducing mosquito abundance. Subsequent removal of emergent vegetation in concert with larvicide applications and reduced daily environmental temperature substantially reduced mosquito abundance. To control Cx. erythrothorax in wetlands, land managers should consider vegetation removal so that larvicide can efficiently enter the water. Vector control agencies may more successfully control adult viremic Cx. erythrothorax that enter nearby neighborhoods by applying adulticides during the 3 h that follow sunset.


Assuntos
Culex/fisiologia , Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/toxicidade , Animais , California , Culex/crescimento & desenvolvimento , Esterases/metabolismo , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Controle de Mosquitos , Permetrina/toxicidade , Butóxido de Piperonila/química , Piretrinas/toxicidade , Áreas Alagadas
20.
Parasitol Res ; 119(9): 2765-2774, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32671542

RESUMO

Before the background of increasingly frequent outbreaks and cases of mosquito-borne diseases in various European countries, Germany recently realised the necessity of updating decade-old data on the occurrence and spatiotemporal distribution of culicid species. Starting in 2011, a mosquito monitoring programme was therefore launched with adult and immature mosquito stages being collected at numerous sites all over Germany both actively by trapping, netting, aspirating and dipping, and passively by the citizen science project 'Mueckenatlas'. Until the end of 2019, about 516,000 mosquito specimens were analysed, with 52 (probably 53) species belonging to seven genera found, including several species not reported for decades due to being extremely rare (Aedes refiki, Anopheles algeriensis, Culex martinii) or local (Culiseta alaskaensis, Cs. glaphyroptera, Cs. ochroptera). In addition to 43 (probably 44 including Cs. subochrea) out of 46 species previously described for Germany, nine species were collected that had never been documented before. These consisted of five species recently established (Ae. albopictus, Ae. japonicus, Ae. koreicus, An. petragnani, Cs. longiareolata), three species probably introduced on one single occasion only and not established (Ae. aegypti, Ae. berlandi, Ae. pulcritarsis), and a newly described cryptic species of the Anopheles maculipennis complex (An. daciae) that had probably always been present but not been differentiated from its siblings. Two species formerly listed for Germany could not be documented (Ae. cyprius, Ae. nigrinus), while presence is likely for another species (Cs. subochrea), which could not be demonstrated in the monitoring programme as it can neither morphologically nor genetically be reliably distinguished from a closely related species (Cs. annulata) in the female sex. While Cs. annulata males were collected in the present programme, this was not the case with Cs. subochrea. In summary, although some species regarded endemic could not be found during the last 9 years, the number of culicid species that must be considered firmly established in Germany has increased to 51 (assuming Cs. subochrea and Ae. nigrinus are still present) due to several newly emerged ones but also to one species (Ae. cyprius) that must be considered extinct after almost a century without documentation. Most likely, introduction and establishment of the new species are a consequence of globalisation and climate warming, as three of them are native to Asia (Ae. albopictus, Ae. japonicus, Ae. koreicus) and three (Ae. albopictus, An. petragnani, Cs. longiareolata) are relatively thermophilic. Another thermophilic species, Uranotaenia unguiculata, which had been described for southwestern Germany in 1994 and had since been found only at the very site of its first detection, was recently documented at additional localities in the northeastern part of the country. As several mosquito species found in Germany are serious pests or potential vectors of disease agents and should be kept under permanent observation or even be controlled immediately on emergence, the German mosquito monitoring programme has recently been institutionalised and perpetuated.


Assuntos
Aedes/classificação , Anopheles/classificação , Culex/classificação , Monitoramento Ambiental/métodos , Mosquitos Vetores/classificação , Ochlerotatus/classificação , Animais , Ásia , Clima , Europa (Continente) , Feminino , Alemanha , Espécies Introduzidas , Masculino
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