Dengue outbreaks in Bangladesh: Historic epidemic patterns suggest earlier mosquito control intervention in the transmission season could reduce the monthly growth factor and extent of epidemics

Concerns for widespread insecticide resistance and the unintended impacts of insecticides on nontarget organisms have generated a pressing need for mosquito control innovations. A yeast RNAi-based insecticide that targets a conserved site in mosquito Irx family genes, but which has not yet been identified in the genomes of nontarget organisms, was developed and characterized. Saccharomyces cerevisiae constructed to express short hairpin RNA (shRNA) matching the target site induced significant Aedes aegypti larval death in both lab trials and outdoor semi-field evaluations. The yeast also induced high levels of mortality in adult females, which readily consumed yeast incorporated into an attractive targeted sugar bait (ATSB) during simulated field trials. A conserved requirement for Irx function as a regulator of proneural gene expression was observed in the mosquito brain, suggesting a possible mode of action. The larvicidal and adulticidal properties of the yeast were also verified in Aedes albopictus, Anopheles gambiae, and Culexquinquefasciatus mosquitoes, but the yeast larvicide was not toxic to other nontarget arthropods. These results indicate that further development and evaluation of this technology as an ecofriendly control intervention is warranted, and that ATSBs, an emerging mosquito control paradigm, could potentially be enriched through the use of yeast-based RNAi technology.

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A Review of the Control of Aedes aegypti (Diptera: Culicidae) in the Continental United States

Journal of Medical Entomology ◽

10.1093/jme/tjaa157 ◽

2020 ◽

Author(s):

Bethany L McGregor ◽

C Roxanne Connelly

Keyword(s):

Aedes Aegypti ◽

Mosquito Control ◽

Effective Control ◽

Source Reduction ◽

Viral Pathogens ◽

Control Programs ◽

Lack Of Information ◽

Dengue Outbreaks ◽

Nuisance Species ◽

Alternative Techniques

Abstract Aedes aegypti (L) is an anthropophilic mosquito involved in the transmission of a variety of viral pathogens worldwide including dengue, chikungunya, yellow fever, and Zika viruses. This species, native to Africa, is well established in the continental U.S. (CONUS) and occasionally contributes to localized outbreaks of viral diseases. In the last seven decades, mosquito control programs in the CONUS have been focused on vectors of eastern equine encephalitis, St. Louis encephalitis, and West Nile viruses, as well as nuisance species. Aedes aegypti receives little control focus except during outbreak periods, which has led to a lack of information on appropriate and effective control options targeting Ae. aegypti in the CONUS. As such, in the event of an Ae. aegypti-borne arboviral outbreak in the CONUS, there are limited evidence-based control recommendations or protocols in place. Autochthonous outbreaks of Ae. aegypti-borne pathogens have occurred recently in the CONUS, including dengue outbreaks in 2010 and 2013, a chikungunya outbreak in 2014, and the 2016 outbreak of Zika virus. The increasing frequency of Ae. aegypti-borne outbreaks necessitates increased attention and research on control of this species to prevent and mitigate future outbreaks. This review consolidates and synthesizes the available literature on control of Ae. aegypti, specifically within the CONUS, focusing on data generated through operational applications as well as field and semifield experiments. The purpose of this review is to identify and highlight areas where additional research is needed. The review covers chemical control and insecticide resistance, biological control, source reduction, trapping, and alternative techniques.

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Towards Integrated Management of Dengue in Mumbai

Viruses ◽

10.3390/v13122436 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2436

Author(s):

Prasad N. Paradkar ◽

Pallavi R. Sahasrabudhe ◽

Mrunal Ghag Sawant ◽

Sandeepan Mukherjee ◽

Kim R. Blasdell

Keyword(s):

Mosquito Control ◽

Integrated Management ◽

Integrated Approach ◽

Control Measures ◽

Adult Mosquito ◽

Breeding Sites ◽

Dengue Disease ◽

Large Cities ◽

Novel Technologies ◽

Dengue Outbreaks

With increasing urbanisation, the dengue disease burden is on the rise in India, especially in large cities such as Mumbai. Current dengue surveillance in Mumbai includes municipal corporation carrying out specific activities to reduce mosquito breeding sites and the use of insecticides to suppress the adult mosquito populations. Clinical cases remain either underreported or misreported due to the restriction to government clinics, missing the large private health care sector. There is a need for an integrated approach to manage dengue outbreaks in Mumbai. There are various novel strategies available for use that can be utilised to improve disease detection, mosquito surveillance, and control of mosquito-borne diseases. These novel technologies are discussed in this manuscript. Given the complex ecosystem of mosquito-borne diseases in Mumbai, integrating data obtained from these technologies would support the ongoing mosquito control measures in Mumbai.

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Asynchronicity of endemic and emerging mosquito-borne disease outbreaks in the Dominican Republic

10.1101/2020.06.17.20133975 ◽

2020 ◽

Author(s):

Mary E. Petrone ◽

Rebecca Earnest ◽

José Lourenço ◽

Moritz U.G. Kraemer ◽

Robert Paulino-Ramirez ◽

...

Keyword(s):

Dominican Republic ◽

Temporal Dynamics ◽

Mosquito Control ◽

Disease Outbreaks ◽

Emerging Diseases ◽

Emerging Disease ◽

Control Measures ◽

Dengue Outbreaks ◽

Temporal And Spatial

ABSTRACTMosquito-borne viruses pose a perpetual public health threat to countries and territories in the Carribean due to the region’s tropical climate and seasonal reception of international tourists. Outbreaks of the emerging viruses chikungunya and Zika in 2014 and 2016, respectively, demonstrated the rapidity with which these viruses can spread between islands. At the same time, the number of reported dengue fever cases, caused by the endemic dengue virus, has steadily climbed over the past decade, and a large dengue outbreak that began sweeping through this region in 2019 continues in 2020. Sustainable disease and mosquito control measures are urgently needed to quell virus transmission in the long term and prevent future outbreaks from occurring. To improve upon current surveillance methods, we analyzed temporal and spatial patterns of chikungunya, Zika, and dengue outbreaks reported in the Dominican Republic between 2012 and 2018. The viruses that caused these outbreaks are transmitted by Aedes mosquitoes, which are sensitive to seasonal climatological variability. In this study, we evaluated whether climate and the spatio-temporal dynamics of past dengue outbreaks could inform when and where future emerging disease outbreaks might occur. We found that the temporal and spatial distribution of emerging disease outbreaks did not conform to those of seasonal dengue outbreaks. Rather, the former occurred when climatological conditions were suboptimal for Aedes activity. Provincial dengue attack rates did not correspond to those of emerging diseases. Our study also provides evidence for under-reporting of dengue cases, especially following the 2016 Zika outbreak. We advocate for the implementation of a sustainable and long-term surveillance system to monitor the spread of known mosquito-borne viruses and to identify emerging threats before they cause outbreaks. Specifically, we recommend the use of febrile illness incidence, ca se fatality rates, and serosurveys during inter-outbreak periods to better understand rates of transmission and asymptomatic infection.

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A trial to assess risk of dengue and evaluate a mosquito control intervention in northeastern Thailand

http://isrctn.com/ ◽

10.1186/isrctn73606171 ◽

2017 ◽

Author(s):

Hans Overgaard

Keyword(s):

Mosquito Control ◽

Control Intervention ◽

Northeastern Thailand

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Neurotoxic Zanthoxylum chalybeum root constituents invoke mosquito larval growth retardation through ecdysteroidogenic CYP450s transcriptional perturbations

10.21203/rs.3.rs-49975/v1 ◽

2020 ◽

Author(s):

Jackson Mbithi Muema ◽

Joel L. Bargul ◽

James M. Mutunga ◽

Meshack A. Obonyo ◽

George O. Asudi ◽

...

Keyword(s):

Growth Retardation ◽

Mosquito Control ◽

Larval Growth ◽

Control Intervention ◽

Vector Control Intervention ◽

Transcriptional Modulation ◽

Sublethal Doses ◽

Bioactive Fraction ◽

Larval Toxicity ◽

Dose Dependent

Abstract Background: Intracellular effects exerted by phytochemicals eliciting insect growth-reducing responses during vector control intervention remain largely underexplored. We studied the effects of Zanthoxylum chalybeum Engl. (Rutaceae) (ZCE) root derivatives against malaria (Anopheles gambiae) and arbovirus vector (Aedes aegypti) larvae to decipher possible molecular targets. Results: We report dose-dependent biphasic effects on larval response, with transient exposure to ZCE and its bioactive fraction (ZCFr.5) inhibiting acetylcholinesterase (AChE) activity, inducing larval lethality and growth retardation at sublethal doses. Half-maximal lethal concentrations (LC50) for ZCE and ZCFr.5 against An. gambiae and Ae. aegypti larvae after 24-h exposure were 9.00 ppm, 12.26 ppm, and 1.58 ppm, 3.21 ppm, respectively. Inhibition of AChE was potentially linked to larval toxicity afforded by 2-tridecanone, palmitic acid (hexadecanoic acid), linoleic acid ((Z,Z)-9,12-octadecadienoic acid), sesamin, β-caryophyllene among other compounds identified in the bioactive fraction. In addition, the phenotypic larval retardation induced by ZCE root constituents were exerted through transcriptional modulation of ecdysteroidogenic CYP450 genes. Conclusion: Collectively, these findings provide an explorative avenue for developing potential mosquito control agents from Z. chalybeum root constituents.

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Quantitative Microscopic Comparison of the Organization of the Lung in Transgenic Mice Expressing Transforming Growth Factor-α (TGF-α)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162533 ◽

1996 ◽

Vol 54 ◽

pp. 14-15

Author(s):

C. G. Plopper ◽

C. Helton ◽

A. J. Weir ◽

J. A. Whitsett ◽

T. R. Korfhagen

Keyword(s):

Growth Factor ◽

Pulmonary Fibrosis ◽

Transgenic Mice ◽

Blood Vessels ◽

Lung Parenchyma ◽

Lung Maturation ◽

Alveolar Air ◽

Parenchymal Tissue ◽

Air Space ◽

Conducting Airways

A wide variety of growth factors are thought to be involved in the regulation of pre- and postnatal lung maturation, including factors which bind to the epidermal growth factor receptor. Marked pulmonary fibrosis and enlarged alveolar air spaces have been observed in lungs of transgenic mice expressing human TGF-α under control of the 3.7 KB human SP-C promoter. To test whether TGF-α alters lung morphogenesis and cellular differentiation, we examined morphometrically the lungs of adult (6-10 months) mice derived from line 28, which expresses the highest level of human TGF-α transcripts among transgenic lines. Total volume of lungs (LV) fixed by airway infusion at standard pressure was similar in transgenics and aged-matched non-transgenic mice (Fig. 1). Intrapulmonary bronchi and bronchioles made up a smaller percentage of LV in transgenics than in non-transgenics (Fig. 2). Pulmonary arteries and pulmonary veins were a smaller percentage of LV in transgenic mice than in non-transgenics (Fig. 3). Lung parenchyma (lung tissue free of large vessels and conducting airways) occupied a larger percentage of LV in transgenics than in non-transgenics (Fig. 4). The number of generations of branching in conducting airways was significantly reduced in transgenics as compared to non-transgenic mice. Alveolar air space size, as measured by mean linear intercept, was almost twice as large in transgenic mice as in non-transgenics, especially when different zones within the lung were compared (Fig. 5). Alveolar air space occupied a larger percentage of the lung parenchyma in transgenic mice than in non-transgenic mice (Fig. 6). Collagen abundance was estimated in histological sections as picro-Sirius red positive material by previously-published methods. In intrapulmonary conducting airways, collagen was 4.8% of the wall in transgenics and 4.5% of the wall in non-transgenic mice. Since airways represented a smaller percentage of the lung in transgenics, the volume of interstitial collagen associated with airway wall was significantly less. In intrapulmonary blood vessels, collagen was 8.9% of the wall in transgenics and 0.7% of the wall in non-transgenics. Since blood vessels were a smaller percentage of the lungs in transgenics, the volume of collagen associated with the walls of blood vessels was five times greater. In the lung parenchyma, collagen was 51.5% of the tissue volume in transgenics and 21.2% in non-transgenics. Since parenchyma was a larger percentage of lung volume in transgenics, but the parenchymal tissue was a smaller percent of the volume, the volume of collagen associated with parenchymal tissue was only slightly greater. We conclude that overexpression of TGF-α during lung maturation alters many aspects of lung development, including branching morphogenesis of the airways and vessels and alveolarization in the parenchyma. Further, the increases in visible collagen previously associated with pulmonary fibrosis due to the overexpression of TGF-α are a result of actual increases in amounts of collagen and in a redistribution of collagen within compartments which results from morphogenetic changes. These morphogenetic changes vary by lung compartment. Supported by HL20748, ES06700 and the Cystic Fibrosis Foundation.

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