scholarly journals Wolbachia strain w AlbB maintains high density and dengue inhibition following introduction into a field population of Aedes aegypti

2020 ◽  
Vol 376 (1818) ◽  
pp. 20190809 ◽  
Author(s):  
Noor Afizah Ahmad ◽  
Maria-Vittoria Mancini ◽  
Thomas H. Ant ◽  
Julien Martinez ◽  
Ghazali M. R. Kamarul ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Control Strategies ◽  
Scale Up ◽  
Virus Transmission ◽  
Kuala Lumpur ◽  
Virus Dissemination ◽  
Laboratory Colony ◽  
Dengue Control ◽  
Additional Support

Aedes aegypti mosquitoes carrying the w AlbB Wolbachia strain show a reduced capacity to transmit dengue virus. w AlbB has been introduced into wild Ae. aegypti populations in several field sites in Kuala Lumpur, Malaysia, where it has persisted at high frequency for more than 2 years and significantly reduced dengue incidence. Although these encouraging results indicate that w AlbB releases can be an effective dengue control strategy, the long-term success depends on w AlbB maintaining high population frequencies and virus transmission inhibition, and both could be compromised by Wolbachia– host coevolution in the field. Here, w AlbB-carrying Ae. aegypti collected from the field 20 months after the cessation of releases showed no reduction in Wolbachia density or tissue distribution changes compared to a w AlbB laboratory colony. The w AlbB strain continued to induce complete unidirectional cytoplasmic incompatibility, showed perfect maternal transmission under laboratory conditions, and retained its capacity to inhibit dengue. Additionally, a field-collected w AlbB line was challenged with Malaysian dengue patient blood, and showed significant blocking of virus dissemination to the salivary glands. These results indicate that w AlbB continues to inhibit currently circulating strains of dengue in field populations of Ae. aegypti , and provides additional support for the continued scale-up of Wolbachia wAlbB releases for dengue control. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases’.

scholarly journals Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control

2019 ◽  
Author(s):  
W. A. Nazni ◽  
A. A. Hoffmann ◽  
A. Noor Afizah ◽  
Y. L. Cheong ◽  
M. V. Mancini ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Virus Transmission ◽  
Larval Rearing ◽  
Kuala Lumpur ◽  
Novel Approach ◽  
Dengue Transmission ◽  
Vector Mosquito ◽  
Primary Vector ◽  
Dengue Control ◽  
Very High

AbstractDengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites, or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates.

scholarly journals Baseline data on the bionomics of Aedes aegypti to support dengue control strategies in Burkina Faso

2019 ◽  
Vol 79 ◽  
pp. 14
Author(s):  
A. Badolo ◽  
A. Sombie ◽  
P. Pignatelli ◽  
F. Yaméogo ◽  
A. Sanon ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Burkina Faso ◽  
Control Strategies ◽  
Baseline Data ◽  
Dengue Control

scholarly journals Citywide Control of Aedes aegypti (Diptera: Culicidae) during the 2016 Zika Epidemic by Integrating Community Awareness, Education, Source Reduction, Larvicides, and Mass Mosquito Trapping

2019 ◽  
Vol 56 (4) ◽  
pp. 1033-1046 ◽  
Author(s):  
Roberto Barrera ◽  
Angela Harris ◽  
Ryan R Hemme ◽  
Gilberto Felix ◽  
Nicole Nazario ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Scale Up ◽  
Virus Transmission ◽  
Medium Size ◽  
Mass Trapping ◽  
Source Reduction ◽  
Community Awareness ◽  
Cluster Randomized

Abstract This investigation was initiated to control Aedes aegypti and Zika virus transmission in Caguas City, Puerto Rico, during the 2016 epidemic using Integrated Vector Management (IVM), which included community awareness and education, source reduction, larviciding, and mass-trapping with autocidal gravid ovitraps (AGO). The epidemic peaked in August to October 2016 and waned after April 2017. There was a preintervention period in October/November 2016 and IVM lasted until August 2017. The area under treatment (23.1 km2) had 61,511 inhabitants and 25,363 buildings. The city was divided into eight even clusters and treated following a cluster randomized stepped-wedge design. We analyzed pools of female Ae. aegypti adults for RNA detection of dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) viruses using 360 surveillance AGO traps every week. Rainfall, temperature, and relative humidity were monitored in each cluster. Mosquito density significantly changed (generalized linear mixed model; F8, 14,588 = 296; P < 0.001) from 8.0 ± 0.1 females per trap per week before the intervention to 2.1 ± 0.04 after the percentage of buildings treated with traps was 60% and to 1.4 ± 0.04 when coverage was above 80%. Out of a total 12,081 mosquito pools, there were 1 DENV-, 7 CHIKV-, and 49 ZIKV-positive pools from October 2016 to March 2017. Afterward, we found only one positive pool of DENV in July 2017. This investigation demonstrated that it was possible to scale up effective Ae. aegypti control to a medium-size city through IVM that included mass trapping of gravid Ae. aegypti females.

scholarly journals Recent outbreaks of chikungunya virus (CHIKV) in Africa and Asia are driven by a variant carrying mutations associated with increased fitness for Aedes aegypti

2018 ◽  
Author(s):  
Irina Maljkovic Berry ◽  
Fredrick Eyase ◽  
Simon Pollett ◽  
Samson Limbaso Konongoi ◽  
Katherine Figueroa ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Chikungunya Virus ◽  
Control Strategies ◽  
Vector Competence ◽  
Virus Transmission ◽  
New Delhi ◽  
African Countries ◽  
Global Spread ◽  
Large Outbreak ◽  
The Impact

AbstractBackgroundIn 2016, a chikungunya virus (CHIKV) outbreak was reported in Mandera, Kenya. This was the first major CHIKV outbreak in the country since the global re-emergence of this virus, which arose as an initial outbreak in Kenya in 2004. Therefore, we collected samples and sequenced viral genomes from the 2016 Mandera outbreak.Methodology/Principal FindingsAll Kenyan genomes contained two mutations, E1:K211E and E2:V264A, recently reported to have an association with increased infectivity, dissemination and transmission in the Aedes aegypti (Ae. aegypti) vector. Phylogeographic inference of temporal and spatial virus relationships using Bayesian approaches showed that this Ae. aegypti adapted strain emerged within the East, Central, and South African (ECSA) lineage of CHIKV between 2005 and 2008, most probably in India. It was also in India where the first large outbreak caused by this strain appeared, in New Delhi, 2010. More importantly, our results also showed that this strain is no longer contained to India, and that it has more recently caused several major outbreaks of CHIKV, including the 2016 outbreaks in India, Pakistan and Kenya, and the 2017 outbreak in Bangladesh. In addition to its capability to cause large outbreaks in different regions of the world, this CHIKV strain has the capacity to replace less adapted wild type strains in Ae. aegypti-rich regions. Indeed, all the latest full CHIKV genomes of the ECSA Indian Ocean Lineage (IOL), from the regions of high Ae. aegypti prevalence, carry these two mutations, including samples collected in Japan, Australia, and China.Conclusions/SignificanceOur results point to the importance of continued genomic-based surveillance of this strain’s global spread, and they prompt urgent vector competence studies in Asian and African countries, in order to assess the level of vector receptiveness, virus transmission, and the impact this might have on this strain’s ability to cause major outbreaks.Author summaryChikungunya virus (CHIKV) causes a debilitating infection with high fever, intense muscle and bone pain, rash, nausea, vomiting and headaches, and persistent and/or recurrent joint pains for months or years after contracting the virus. CHIKV is spread by two mosquito vectors, Aedes albopictus and Aedes aegypti, with increased presence around the globe. In this study, we report global spread of a CHIKV strain that carries two mutations that have been suggested to increase this virus’ ability to infect the Aedes aegypti mosquito, as well as to increase CHIKV’s ability to be transmitted by this vector. We show that this strain appeared sometime between 2005 and 2008, most probably in India, and has now spread to Africa, Asia, and Australia. We show that this strain is capable of driving large outbreaks of CHIKV in the human population, causing recent major outbreaks in Kenya, Pakistan, India and Bangladesh. Thus, our results stress the importance of monitoring this strain’s global spread, as well as the need of improved vector control strategies in the areas of Aedes aegypti prevalence.

scholarly journals A decade of stability for wMel Wolbachia in natural Aedes aegypti populations

2021 ◽  
Author(s):  
Perran A Ross ◽  
Katie L Robinson ◽  
Qiong Yang ◽  
Ashley G Callahan ◽  
Thomas L Schmidt ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Cytoplasmic Incompatibility ◽  
Near Field ◽  
Virus Transmission ◽  
Host Density ◽  
Disease Suppression ◽  
Genomic Changes ◽  
Laboratory Populations ◽  
Wolbachia Genome

Mosquitoes carrying Wolbachia endosymbionts are being released in many countries for arbovirus control. The wMel strain of Wolbachia blocks Aedes-borne virus transmission and can spread throughout mosquito populations by inducing cytoplasmic incompatibility. Aedes aegypti mosquitoes carrying wMel were first released into the field in Cairns, Australia, over a decade ago, and with wider releases have resulted in the near elimination of local dengue transmission. The long-term stability of Wolbachia effects is critical for ongoing disease suppression, requiring tracking of phenotypic and genomic changes in Wolbachia infections following releases. We used a combination of field surveys, phenotypic assessments, and Wolbachia genome sequencing to show that wMel has remained stable in its effects for up to a decade in Australian Ae. aegypti populations. Phenotypic comparisons of wMel-infected and uninfected mosquitoes from near-field and long-term laboratory populations suggest limited changes in the effects of wMel on mosquito fitness. Treating mosquitoes with antibiotics used to cure the wMel infection had limited effects on fitness in the next generation, supporting the use of tetracycline for generating uninfected mosquitoes without off-target effects. wMel has a temporally stable within-host density and continues to induce complete cytoplasmic incompatibility. A comparison of wMel genomes from pre-release (2010) and nine years post-release (2020) populations show few genomic differences and little divergence between release locations, consistent with the lack of phenotypic changes. These results indicate that releases of Wolbachia-infected mosquitoes for population replacement are likely to be effective for many years, but ongoing monitoring remains important to track potential evolutionary changes.

scholarly journals Wolbachia pipientis occurs in Aedes aegypti populations in New Mexico and Florida, USA

2018 ◽  
Author(s):  
Aditi Kulkarni ◽  
Wanqin Yu ◽  
Jinjin Jiang ◽  
Concepcion Sanchez ◽  
Ajit K. Karna ◽  
...  
Keyword(s):  
New Mexico ◽  
Aedes Aegypti ◽  
Control Strategies ◽  
Vector Competence ◽  
Virus Transmission ◽  
Lamp Assay ◽  
Harris County ◽  
Pcr Assay ◽  
Wolbachia Pipientis ◽  
Pcr Products

ABSTRACTThe mosquitoes Aedes aegypti (L.) and Ae. albopictus Skuse are the major vectors of dengue, Zika, yellow fever and chikungunya viruses worldwide. Wolbachia, an endosymbiotic bacterium present in many insects, is being utilized in novel vector control strategies to manipulate mosquito life history and vector competence to curb virus transmission. Earlier studies have found that Wolbachia is commonly detected in Ae. albopictus but rarely detected in Ae. aegypti. In this study, we used a two-step PCR assay to detect Wolbachia in wild-collected samples of Ae. aegypti. The PCR products were sequenced to validate amplicons and identify Wolbachia strains. A loop-mediated isothermal amplification (LAMP) assay was developed and used for detecting Wolbachia in selected mosquito specimens as well. We found Wolbachia in 85/148 (57.4%) wild Ae. aegypti specimens from various cities in New Mexico and in 2/46 (4.3%) from St. Augustine, Florida. We did not detect Wolbachia in 94 samples of Ae. aegypti from Deer Park, Harris County, Texas. Wolbachia detected in Ae. aegypti from both New Mexico and Florida was the wAlbB strain of Wolbachia pipientis. A Wolbachia positive colony of Ae. aegypti was established from pupae collected in Las Cruces, New Mexico in 2018. The infected females of this strain transmitted Wolbachia to their progeny when crossed with males of Rockefeller strain of Ae. aegypti, which does not carry Wolbachia. In contrast, none of the progeny of progeny of Las Cruces males mated to Rockefeller females were infected with Wolbachia.

scholarly journals High temperature cycles result in maternal transmission and dengue infection differences between Wolbachia strains in Aedes aegypti

2020 ◽  
Author(s):  
Maria Vittoria Mancini ◽  
Thomas H. Ant ◽  
Christie S. Herd ◽  
Daniel D. Gingell ◽  
Shivan M. Murdochy ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Aedes Aegypti ◽  
Virus Transmission ◽  
Temperature Cycle ◽  
Larval Rearing ◽  
Mosquito Vector ◽  
Maternal Transmission ◽  
Rearing Temperature ◽  
Dengue Control ◽  
The Impact

AbstractEnvironmental factors play a crucial role in the population dynamics of arthropod endosymbionts, and therefore in the deployment of Wolbachia symbionts for the control of dengue arboviruses. The potential of Wolbachia to invade, persist and block virus transmission depends in part on its intracellular density. Several recent studies have highlighted the importance of larval rearing temperature in modulating Wolbachia densities in adults, suggesting that elevated temperatures can severely impact some strains, while having little effect on others. The effect of a replicated tropical heat cycle on Wolbachia density and levels of virus blocking was assessed using Aedes aegypti lines carrying strains wMel and wAlbB, two Wolbachia strains currently used for dengue control. Impacts on intracellular density, maternal transmission fidelity and dengue inhibition capacity were observed for wMel. In contrast wAlbB-carrying Ae. aegypti maintained a relatively constant intracellular density at high temperatures and conserved its capacity to inhibit dengue. Following larval heat treatment, wMel showed a degree of density recovery in aging adults, although this was compromised by elevated air temperatures. When choosing the Wolbachia strain to be used in a dengue control programme it is important to consider the effects of environmental temperatures on invasiveness and virus inhibition.Author summaryIn the past decades, dengue incidence has dramatically increased all over the world. An emerging dengue control strategy utilizes Ae. aegypti mosquitoes artificially transinfected with the bacterial symbiont Wolbachia, with the ultimate aim of replacing wild mosquito populations. Wolbachia is transmitted from mother to offspring and is able to interfere with virus transmission within the mosquito vector. However, the rearing temperature of mosquito larvae is known to impact on some Wolbachia strains. In this study, we compared the effects of a temperature cycle mimicking natural breeding sites in tropical climates on two Wolbachia strains, currently used for open field trials. We observed that the strain wMel was susceptible to high larval rearing temperatures, while the strain wAlbB resulted to be more stable. These results underlines the importance of understanding the impact of environmental factors on released mosquitoes, in order to ensure the most efficient strategy for dengue control.

From Start-Up to Scale-Up

2018 ◽  
Author(s):  
Gilles Duruflé ◽  
Thomas Hellmann ◽  
Karen Wilson
Keyword(s):  
United States ◽  
Conceptual Framework ◽  
Public Policies ◽  
Scale Up ◽  
The United States ◽  
Smart Money ◽  
Start Up ◽  
The Us ◽  
The Creation

This chapter examines the challenge for entrepreneurial companies of going beyond the start-up phase and growing into large successful companies. We examine the long-term financing of these so-called scale-up companies, focusing on the United States, Europe, and Canada. The chapter first provides a conceptual framework for understanding the challenges of financing scale-ups. It emphasizes the need for investors with deep pockets, for smart money, for investor networks, and for patient money. It then shows some data about the various aspects of financing scale-ups in the United States, Europe, and Canada, showing how Europe and Canada are lagging behind the US relatively more at the scale-up than the start-up stage. Finally, the chapter raises the question of long-term public policies for supporting the creation of a better scale-up environment.

scholarly journals Adopt, adapt, or abandon technology-supported person-centred care initiatives: healthcare providers’ beliefs matter

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kari Dyb ◽  
Gro Rosvold Berntsen ◽  
Lisbeth Kvam
Keyword(s):  
Information Technologies ◽  
Scale Up ◽  
Healthcare Providers ◽  
Healthcare Services ◽  
Analytical Framework ◽  
Development Project ◽  
Technology Support ◽  
Care Needs ◽  
Term Care

Abstract Background Technology support and person-centred care are the new mantra for healthcare programmes in Western societies. While few argue with the overarching philosophy of person-centred care or the potential of information technologies, there is less agreement on how to make them a reality in everyday clinical practice. In this paper, we investigate how individual healthcare providers at four innovation arenas in Scandinavia experienced the implementation of technology-supported person-centred care for people with long-term care needs by using the new analytical framework nonadoption, abandonment, and challenges to the scale-up, spread, and sustainability (NASSS) of health and care technologies. We also discuss the usability and sensitivity of the NASSS framework for those seeking to plan, implement, and evaluate technology-supported healthcare programmes. This study is part of an interdisciplinary research and development project called Patients and Professionals in Partnership (2016–2020). It originates at one of ten work packages in this project. Method The main data consist of ethnographic field observations at the four innovation arenas and 29 interviews with involved healthcare providers. To ensure continuous updates and status on work in the four innovation arenas, we have also participated in a total of six annual network meetings arranged by the project. Results While the NASSS framework is very useful for identifying and communicating challenges with the adoption and spread of technology-supported person-centred care initiatives, we found it less sensitive towards capturing the dedication, enthusiasm, and passion for care transformation that we found among the healthcare providers in our study. When it comes to technology-supported person-centred care, the point of no return has passed for the involved healthcare providers. To them, it is already a definite part of the future of healthcare services. How to overcome barriers and obstacles is pragmatically approached. Conclusion Increased knowledge about healthcare providers and their visions as potential assets for care transformation might be critical for those seeking to plan, implement, and evaluate technology-supported healthcare programmes.

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