Malaria is a potentially lethal parasitic disease that is spread by the bites of infected mosquitoes from the Anopheles family. Despite extensive gains in preventing and treating malaria, the disease remains a major public health threat in many parts of the world. While insecticide-treated bed nets (ITNs) have served as the mainstay of malaria prevention, new approaches to control malaria by disrupting transmission can complement ITNs and other existing approaches. This article details these emerging approaches, describing how they work and their potential contributions to malaria control.
The Limitations of Bed Nets
The insecticide-treated bed net (ITN), primarily an indoor means of malaria control, works by forming a physical barrier between people and mosquitoes, while the insecticide repels or kills any mosquitoes that land on the net. However, bed nets come with numerous practical limitations:
- Coverage gap: Not everybody is covered by bed nets, particularly when these are poor or remote areas.
- Maintenance problems: bed nets can wear, or be mishandled or replaced in ways that diminish their effectiveness.
- Behavioral Factors: People might not always use bed nets consistently or correctly.
- Resistance: Mosquitoes are becoming resistant to the insect
These limitations need to be addressed with a multifaceted approach that extends far beyond bed nets. Here are a few of the latest strategies under development and in use.
1. Genetic Modification of Mosquitoes
More exciting still is a new genetically modified approach to intervention that has been trialed for malaria prevention. Several approaches are underway:
Gene Editing
For instance, through gene editing such as CRISPR-Cas9 – which can delete genes that the mosquitoes need to pass on to successful offspring – the hope is to make them sterile. Other scientists are trying to use gene editing techniques to make mosquitoes impotent. Mosquitoes cannot catch the infections that they spread, but they can harbor them and transfer them to humans that they bite using their sting. Because of this, scientists are designing mosquitoes that will dramatically reduce the tally of serious diseases. This year alone, scientists in Australia reported the use of gene editing for disease control by creating mosquitoes that cannot transmit malaria. A similar approach is currently being trialed in Malawi. Another detailed study uses mice to show why mosquito control hasn’t allowed us to declare victory over the entire family of parasites including diseases such as malaria, yellow fever, dengue, and Zika.
- Sterile Insect Technique: Engineers sterile GM males which, upon mating with their wild sisters, ensure that no offspring are produced. This method reduces the mosquito population slowly over time.
- Genetic drive systems: Genetically engineering mosquitoes so that genetic changes – for example, making the mosquito more resistant to malaria – spread rapidly through the generations, possibly ultimately to a population-wide change that could reduce malaria transmission.
Release of Genetically Engineered Mosquitoes
Global efforts are beginning to target vector species, including trials in the Florida Keys of freely bred genetically modified mosquitoes intended to reduce mosquito populations or render them incapable of conveying malaria parasites from person to person. Preliminary trials in test environments have been encouraging, but large-scale studies are required to understand their ecological
2. Malaria Vaccines
Vaccines are one of the greatest achievements in malaria prevention. The RTS, S/AS01 malaria vaccine, marketed as Mosquirix, is the most recognized first-in-class vaccine and has been deployed in multiple countries. Meanwhile, researchers are actively developing new vaccines aimed at improving efficacy and providing longer-lasting protection.
RTS, S/AS01 Vaccine
- Mechanism: The vaccine stimulates the immune system to fight against the malaria-causing Plasmodium falciparum parasite. This was the most lethal but also the most widespread type.
- Effectiveness: It reduces cases of malaria but is only partial protection and multiple shots are needed.
Next-Generation Vaccines
Moreover, research teams are working on more sophisticated malaria vaccines that attack specific life stages of the parasite or novel immunization approaches such as the mRNA technology now used for highly effective COVID-19 vaccines. Such vaccines will be more broad and lasting.
3. Innovative Insecticides and Repellents
New insecticides and repellents are being developed to tackle mosquito resistance and improve effectiveness:
Novel Insecticides
- New chemical classes are being sought that mosquitoes haven’t yet evolved resistance to.
- Biological Control: Employing naturally occurring substances or organisms that can kill or repel mosquitoes, without endangering other wildlife.
Long-Lasting Insecticidal Nets (LLINs)
The good news is that LLINs have greater longevity with effective insecticides than standard-impregnated bed nets, so they need to be replaced less frequently and continuously provide protection.
Repellents
- Chemical Repellents Make longer-lasting insect repellents that can be applied to skin or clothes.
- Natural Repellents: Research into plant-based or natural repellents that are effective yet environmentally friendly.
4. Environmental Management
Environmental management centers around controlling the multiplication of mosquitoes by reducing breeding sites and limiting the mosquito population through habitat modification:
Larviciding
Applying larvicides to bodies of water that harbor breeding mosquitoes kills the larvae before they develop into adult mosquitoes. New larvicides will kill only specific mosquito species and will not affect other aquatic life.
Source Reduction
Standing water sources could be eliminated or modified, for instance through better management of urban waste or water retention spaces. Control methods of this type, however, require resources and cannot be rapidly deployed to combat new epidemics.
Biological Control Agents
Bringing in predators of mosquito larvae – such as fish or insects – provides natural mosquito suppression.
5. Community Engagement and Education
This is essential to the success of malaria prevention programs. Community education about malaria transmission and prevention also amplifies the impact of interventions:
Behavioral Change Campaigns
- Awareness Programs: Educating people about the value of using bed nets, seeking treatment promptly, and removing mosquito breeding sites.
- Community-Based Interventions: Involving local leaders and organizations in promoting malaria prevention practices.
Health Education
- Schools and Institutions: Use the curriculum and community health programs to instill the importance of malaria prevention at an early age.
- Media campaigns: Using radio, TV, and social media to spread information about preventing and treating malaria.
6. Integrated Vector Management (IVM)
So-called Integrated Vector Management (IVM) coordinates all these techniques using biological, chemical, and physical controls to manage vector populations:
Combining Methods
- Shaking hands with Pinto and Jacobs, an old dog shielded by an insecticide-treated net (ITN) peers out the door Shifting our focus towards fighting uniformity is just as important as acknowledging it. Combined and complementary efforts, including the use of ITNs with indoor residual spraying (IRS) and environmental management, might present our most promising options.
- Cross-Sectoral Cooperation: Bringing actors from health, agriculture, and environmental sectors to the table to tackle malaria from multiple approaches.
Data-Driven Approaches
- Surveillance systems: Establishing systems to monitor populations for cases of malaria and mosquito populations, so that targeted action can occur.
- Research and Development: Provide funds for research on malaria control to ensure that interventions continue to be evaluated and adapted as new data on program effectiveness emerges.
Insecticide-treated bed nets have formed the backbone against malaria, but here too we see a flight of innovation to complement and go beyond these sturdy, undeniable front-line weapons. Genetically modified (GM) mosquitoes, greatly improved vaccines and insecticides are all possibilities in a continuing search for the end of malaria. We should integrate the new with the tried and true, and work with local communities to avoid sidestepping past successes. Already, both donor and local financial contributions have completely vanquished malaria in places such as the Cook Islands to the west and Sri Lanka to the east. Malaria will not go quietly. But it can be made to surrender.
The more we learn and apply these creative approaches, the more likely we are to encourage a collaborative approach that involves a diversity of actors and mindsets. As a result, we can develop promising management strategies that will bring us one step closer to a future free of malaria as a public health menace. Ultimately, this collective effort can lead to innovative solutions and a stronger response to the challenges posed by malaria.
