This workstream concerns the arms race against insecticide resistance in African malaria vector mosquitoes. In particular, it concerns the process of choosing the most cost-effective insecticidal interventions in the face of complex geographic variation in resistance and a limited amount of epidemiological trial evidence.
This workstream addresses the more strategic and longer-term threats facing vector control, including the rise of Aedes-borne viruses in Africa, and the effects of anthropogenic land-use changes.
RAFT will focus on the most pressing challenges in vector control for mosquito-borne diseases, especially malaria and Aedes-borne viruses.
In the case of malaria, increased access to insecticidal nets supported by international donors has prevented many millions of child deaths in Africa. But these gains are under threat, and could be lost, because insecticide resistance in mosquitoes threatens to erode the protection provided by nets. The good news: we are now seeing the advent of new products with new active ingredients and new tools with new modes of action. However, insecticide resistance is geographically varied. Moreover, donors currently spend more than USD 0.5 billion per year on these products, and RAFT believes that the value-for-money of this expenditure can be improved. The RPC addresses this in Workstream 1 by combining entomological and genetic research in sub-Saharan Africa with mathematical modelling and economic analysis. We will then develop a decision-support tool to guide the selection and deployment of these new products in a cost-effective manner.
RAFT will also strengthen the capacity of national control programmes to tackle two emerging mosquito vectors: Aedes spp. and Anopheles stephensi. Viruses transmitted by Aedes mosquitoes, such as dengue, Chikungunya and Zika, are another rapidly rising problem around the world. These mosquitoes thrive in man-made breeding sites which have increased due to urban expansion over the last few decades. The very recent expansion of An. stephensi into African cities is an additional urgent concern. Intensified transmission in urban centres that previously had little or no malaria could be a major setback for malaria control in the region. It is estimated that by 2025, more than half the African population will live in cities. In Africa, where malaria (a rural disease) has historically been the main focus, knowledge about the biology and control of urban mosquitoes like Aedes and An. stephensi is especially weak. To address this, Workstream 2 of the RPC will:
- Conduct research in Asia and Africa (on the effects of anthropogenic development processes on the epidemiology of mosquito-borne diseases) and
- Set up exchange visits to harness expertise from other continents (including central America and Asia).
- Workstream 1: Current threats
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Maintaining effective malaria vector control in Africa
Long-lasting insecticidal nets (LLINs) represent approximately 45% of global spending on malaria control. They are also responsible for around 2/3s of the reduction in malaria burden since 2000; over the last 15 years, improved coverage with effective malaria control (especially LLINs) has prevented more than 6 million deaths in sub-Saharan Africa.
However, these gains are fragile: they will be lost if we fail to sustain coverage with effective vector control. Unfortunately, both sustained coverage and effectiveness are under threat, due to limits on donor funding and the rapid evolution of insecticide resistance in African vectors. Various new and more expensive vector control products are being developed and becoming available, but insecticide resistance in SSA varies greatly from place to place.
Anopheles gambiae – credit: Flickr © Anders L Thus, national malaria programme managers are faced with a wide variety of questions about cost-effectiveness and value-for-money in resistance management.
The main task for workstream 1 is therefore to address this question: “Given the resistance situation in a target area, and the prices of the available LLIN products, which is the most cost-effective LLIN for that region?”
Our research plan
- Generate entomological data from experimental hut trials [image labelled experimental huts] in our partner countries (Cameroon, Côte d’Ivoire and Tanzania)
- Model the expected performance of each LLIN in a target area [image labelled modelling]
- Develop an economic analysis of the product choice decision [image labelled economic analysis]
- Workstream 2: Future Threats
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Anticipating and preparing for other emerging VBD threats
This workstream addresses emerging and future threats, and has two core functions:
- Horizon scanning – research on emerging issues and trends that threaten to increase the transmission of mosquito-borne diseases and/or undermine vector control
- Building resilience – working with vector control programmes to enhance core capabilities required to detect and respond to emerging threats, and ensuring timely access to relevant technical resources and know-how.
Why is this important?
We will focus on threats which could arise from ongoing processes of development. Human-made landscapes (rural and urban) occupy an ever-increasing fraction of the land-surface of the planet. Urbanisation is a key trend in many developing economies; by 2025, it is estimated that more than 50% of the population in Africa will lie in cities. Two disease vectors thrive in these urban environments:
Aedes aegypti, the primary vector of arboviral diseases (such as dengue, Zika, chikungunya and yellow fever). Aedes-borne arboviruses are a growing problem around the world, yet control is hampered by a lack of fundamental knowledge on disease burden, vector ecology and effective interventions.
Aedes aegyti – credit: Flickr © Anders L Anopheles stephensi, an efficient urban vector of malaria. Originating from South Asia, An. stephensi has been invading cities across sub-Saharan Africa
Anopheles stephensi – credit: Flickr © Anders L Workstream 2 will consist of four strands of work
- Strengthening expertise on the control of urban mosquitoes: We will be evaluating the Aedes-borne virus situation in Africa and Asia, preparing for the invasion of Anopheles stephensi in Africa, and strengthening research capacity by organising South-South exchange visits between experts in Central America, Africa and Asia.
- The effect of anthropogenic change on mosquito-borne diseases: We will focus on human development trends most likely to impact the risk of VBDs by creating environments which alter human-vector contact, mosquito survival or reproductive success. These are namely changes in housing, electrification, water storage and irrigation.
- Resilience-preparedness for future threats and response plans: How can national disease control programmes prepare for the future, including the threat of invasive new infections? How can we manage human-made landscapes without creating opportunities and niches for vectors? How can we integrated VBD control into intersectoral discussions and national economic development plans? RAFT will attempt to address these questions.
- Vector control in complex humanitarian emergencies: Complex emergency scenarios require specialised interventions. We review the vector control technologies which are effective against malaria in these situations.
Consortium members
The RAFT RPC is funded by the UK Foreign, Commonwealth and Development Office. Alongside LSHTM, it is a multi-centre consortium conducted by:
- Centre for Research in Infectious Disease in Cameroon (CRID-CAM)
- Institut Pierre Richet in Côte d’Ivoire
- National Institute for Medical Research (NIMR) in Tanzania
- Imperial College London
- Faculty of Tropical Medicine of Mahidol University in Thailand
- Malaria Consortium
Meet the team
- LSHTM
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- Jo Lines, Research Director
- Sian Clarke, Research Director
- Jo Honeybone, Chief Executive Officer
- Maria Bernardez, Programme Manager
- Kallista Chan, Research Uptake Manager
- Research Partner Institutions
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- Charles Wondji, CRID-CAM, Principal Investigator
- Raphael N’Guessan, IPR, Principal Investigator
- Alphaxard Manjurano, NIMR, Principal Investigator
- Tom Churcher, Imperial College, Principal Investigator
- Patchara Sriwichai, Mahidol University, Principal Investigator
- James Tibenderana, Malaria Consortium, Principal Investigator
- Consortium Governance
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- RAFT Management Board: Composed of the lead investigators (PIs) from each partner institution and the RPC research directors, CEO, Programme Manager and Research Uptake Manager
- Consortium Advisory Group (CAG): Composed of international stakeholders in vector control and leading academics in global health
- Interdisciplinary Academic Advisory Group (IIAG): Composed of researchers from Knowledge Centres at LSHTM (Malaria Centre, Health in Humanitarian Crises Centre, Centre for Epidemic Preparedness and Response, WHO Collaborating Centre on Climate Change, Health and Sustainable Development)
The research and data produced and contributed to by RAFT members is available here, including:
- Journal articles
- Briefs (project, policy)
- Books, chapters and sections
- Conferences, workshops and presentations
- Seminars and lectures
- Posters
- Media
- Blogs
About RAFT
Workstream 1: Current threats – insecticide resistance
- Journal articles
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- Association of Reduced Long-Lasting Insecticidal Net Efficacy and Pyrethroid Insecticide Resistance With Overexpression of CYP6P4, CYP6P3, and CYP6Z1 in Populations of Anopheles coluzzii From Southeast Côte d'Ivoire
- Assessing the efficacy of two dual-active ingredients long-lasting insecticidal nets for the control of malaria transmitted by pyrethroid-resistant vectors in Benin: study protocol for a three-arm, single-blinded, parallel, cluster-randomized controlled trial
- Impact and cost-effectiveness of a lethal house lure against malaria transmission in central Côte d'Ivoire: a two-arm, cluster-randomised controlled trial
- Protocol for a four parallel-arm, single-blind, cluster-randomised trial to assess the effectiveness of three types of dual active ingredient treated nets compared to pyrethroid-only long-lasting insecticidal nets to prevent malaria transmitted by pyrethroid insecticide-resistant vector mosquitoes in Tanzania
- Pre-intervention characteristics of the mosquito species in Benin in preparation for a randomized controlled trial assessing the efficacy of dual active-ingredient long-lasting insecticidal nets for controlling insecticide-resistant malaria vectors
- An increasing role of pyrethroid-resistant Anopheles funestus in malaria transmission in the Lake Zone, Tanzania
- On the cost-effectiveness of insecticide-treated wall liner and indoor residual spraying as additions to insecticide treated bed nets to prevent malaria: findings from cluster randomized trials in Tanzania
- Overabundance of Asaia and Serratia Bacteria Is Associated with Deltamethrin Insecticide Susceptibility in Anopheles coluzzii from Agboville, Côte d'Ivoire
- A whole transcriptomic approach provides novel insights into the molecular basis of organophosphate and pyrethroid resistance in Anopheles arabiensis from Ethiopia
- Developing Consensus Standard Operating Procedures (SOPs) to Evaluate New Types of Insecticide-Treated Nets
- Investigating molecular mechanisms of insecticide resistance in the Eastern Democratic Republic of the Congo
- Optimising the deployment of vector control tools against malaria: a data-informed modelling study
- Large-scale (Phase III) evaluation of broflanilide 50WP (VECTRON™ T500) for indoor residual spraying for malaria vector control in Northeast Tanzania: study protocol for a two-arm, non-inferiority, cluster-randomised community trial
- Strain Characterisation for Measuring Bioefficacy of ITNs Treated with Two Active Ingredients (Dual-AI ITNs): Developing a Robust Protocol by Building Consensus
- High-throughput barcoding method for the genetic surveillance of insecticide resistance and species identification in Anopheles gambiae complex malaria vectors
- Webinars / Conferences
- Other resources
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- Malaria Intervention tool (MINT) to guide malaria control decision making: and user guide
- Turning houses into ‘lethal mosquito lures’ nearly halves incidence of malaria in children (Press release)
- Briefs
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- Addressing insecticide resistance - English
- Addressing insecticide resistance - French
- Case studies in insecticide resistance management - English
Workstream 2: Future threats – anticipating the effects of anthropogenic change on mosquito-borne disease
- Journal articles
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- Anopheles stephensi Mosquitoes as Vectors of Plasmodium vivax and falciparum, Horn of Africa, 2019
- A whole transcriptomic approach provides novel insights into the molecular basis of organophosphate and pyrethroid resistance in Anopheles arabiensis from Ethiopia
- Malaria transmission and prevalence in rice-growing versus non-rice-growing villages in Africa: a systematic review and meta-analysis
- Vector control for malaria prevention during humanitarian emergencies: protocol for a systematic review and meta-analysis
- Towards environmental detection, quantification, and molecular characterization of Anopheles stephensi and Aedes aegypti from experimental larval breeding sites
- Developing African arbovirus networks and capacity strengthening in arbovirus surveillance and response: findings from a virtual workshop
- The control of malaria vectors in rice fields: a systematic review and meta‑analysis
- Spatial distribution and insecticide resistance profile of Aedes aegypti and Aedes albopictus in Douala, the most important city of Cameroon
- Webinars / Conferences
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- Aedes-borne diseases: Building resilience against future threats
- Stephensi in Africa
- Global Landscape Analysis of Training Courses in Medical Entomology for vector-borne disease control – lessons learned from existing courses and summary of needs assessment
- Malaria No More Japan: Study Session “Rice Production and Malaria in Africa”
- World Mosquito Day 2020: Malaria Centre Spotlight on…Anopheles stephensi: A future threat in Africa?
- Larval Source Management: Historical successes, current challenges, and future potential
- International Conference “Rice Cultivation and Malaria Control in sub-Saharan Africa
- Aedes & Stephensi: a MasterClass with Profs. Peter Ryan, Basile Kamgang & Fitsum G. Tadesse
- Other resources
- Briefs
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- Anopheles stephensi in Africa - English
- Anopheles stephensi in Africa - French
- Rice and malaria in Africa - English
- Rice and malaria in Africa - French
- Vector control in humanitarian emergencies - English
- Vector control in humanitarian emergencies - French