Vector Control: addressing future challenges in the fight against Malaria

What major challenges are we currently facing in the fight against Malaria?

Dr. Frédéric Schmitt - I think the most important one is that we need enough resources to cover as many people as possible – all the while operating with limited budgets. This is why we have to develop new Vector Control solutions: these must be both cheaper (to produce and to implement) and long-lasting.

Here’s another challenge, which has a direct link with the previous one: we need to be able to deploy the operations in all Malaria-stricken areas. Most of the time, Malaria programs can only cover the most severely affected areas because they don’t have enough resources to take action everywhere.

As of today, Malaria control actions are mainly focused on indoor transmission (in households), through indoor residual spraying and Long-Lasting Insecticide Nets. Very few outdoor intervention options designed to limit residual transmission are available today.

Personal protection – via topical repellents and limb-covering clothes – are the most easily implemented strategies, but in practice they aren’t widely used because of the heat and the products’ high cost. Recent innovations, based on the Attract-and-Kill approach, are currently being tested and should be available in a few years.

Have some new challenges emerged recently?

Other challenges have appeared in the last decade and keep getting more and more serious. Resistance development is definitely one of those. Up until now, very few modes of action have been available on the market: mosquitoes were over-exposed to a small number of molecules, which caused these molecules to lose their effectiveness. For more than 30 years, no new molecules were created in the Vector Control sector. Only in 2019/2020 – when neonicotinoids appeared on the market – did we start having access to actual alternatives. These enabled a better implementation of resistance management strategies, through rotation or mosaic use of products.

The last challenge I’d like to mention here is the invasion of new species: as people and goods circulate, some species colonize new geographical areas. This mainly happens in Africa, with the Anopheles stephensi mosquito – a Malaria vector that usually thrives in urban areas and is already resistant to many insecticides. In this context, the use of space spraying – with products designed for resistance management – can be an effective strategy to control mosquito populations.

What strategies can be used to tackle these new challenges?

F. S. - Tackling the resistance issue requires developing and implementing new combinations and rotations of existing solutions, because exposing a mosquito to two modes of action simultaneously limits resistance development. We also need new intervention types. Envu is currently working hand in hand with the Tanzania Ifakara Health Institute on a project that involves eave-ribbons treated with various insecticide formulations. These must be installed between walls and roofs to enhance indoor and outdoor peridomestic protection.

Targeted use of larvicides could be another solution, but it hasn’t been implemented on a large scale yet (at least in Malaria control) because it’s a complex process: limiting stagnant water areas is nearly impossible in tropical countries where it rains daily. But some tests are currently being carried out in a few urban and peri-urban areas like Zanzibar, where drones are used to detect larval habitats. Another possibility would be to develop granules that give off their substance when they enter in contact with water.

Besides, outdoor space spraying mustn’t be overlooked: considering the resurgence of other “urban” vector diseases such as Dengue and Chikungunya, this Vector Control strategy is gaining momentum in urban and peri-urban areas. This is what’s happening in Ivory Coast, among other countries.

Is it easy to innovate in the Vector Control sector?

F. S. - In my opinion, no. We have to make do with limited budgets. Luckily we have faithful partners, like IVCC, that help us finance innovative projects.

Time is another challenge. Developing a new product requires 5-7 years minimum. Once it is ready, we have to get the approval of regulatory authorities (WHO and local authorities), and things get even more complex if we want to create a new intervention class : first, the new solution is assessed by the Vector Control Advisory Group (VGAC) and then we receive testing guidelines. Large-scale epidemiological trials are often required by the WHO to enable them to develop policy guidance on how to use these new intervention classes. This is a long and expensive process.

How is Envu taking action in this context?

F. S. - I am deeply convinced that in order to be really efficient, we need to extend our range of action. This is why we, at Envu, are operating on multiple fronts!

As a global market leader in insecticide solutions, we are spearheading the development of IRS with our products (especially Fludora® Fusion) and we are working on new outdoor spraying solutions and larvicides. We also provide bed nets manufacturers with high-quality active ingredients and specific formulations. Here’s another example: our innovative combination space spray Fludora® Co-Max, which is based on a new mode of action, is widely used for Aedes control in Dengue-stricken areas like Brazil and West Africa.

In order to reduce insecticide resistance, we strive to design new modes of action. It can range from the repurposing of agricultural active substances to the creation of new active substances with the help of IVCC.

We are committed to educating populations and raising awareness, because we believe that people need to understand Malaria (what it is and how it spreads) to welcome Vector Control solutions. We also train our sprayer operators to help them use our products in the best possible way, efficiently and safely. Also, to reduce the environmental impact of leftover product and of the water used to clean spray equipment, we implemented a Phytobac® solution in Rwanda in order to evacuate waste optimally.

Whether on site or in research labs, Envu is committed to tackling the current and future challenges of Vector Control. Along with WHO and all the stakeholders of this sector, we are working towards a future free of Malaria.