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In this blog post, Gates Open Research speaks to Dr. Koama Bayili (Institut de Recherche en Sciences de la Santé) about his Research Article, which explores using a new indoor residual spraying (IRS) approach against insecticide-resistant malaria in Burkina Faso. 

First, let’s meet the author

Dr. Koama Bayili is a medical entomologist at the Institut de Recherche en Sciences de la Santé (IRSS) in Burkina Faso. He manages insectarium and insecticide testing facilities and undertakes research into insecticide resistance. 

He works alongside Professor Abdoulaye Diabaté, Head of Medical Entomology and Parasitology at IRSS, and in collaboration with the Innovative Vector Control Consortium (IVCC) and wider stakeholders to develop novel and improved public health insecticides and products to combat the rapidly growing problem of insecticide-resistant malaria vectors. 

He gained his Ph.D. from Université Nazi Boni of Bobo-Dioulasso in Burkina Faso, focusing on evaluating new formulations of insecticides in phase I & II trials against vector-borne diseases that are resistant to pyrethroids. 

Can you tell us more about indoor residual spraying in malaria control?

Malaria remains one of Africa’s most critical public health problems, despite intense national and international efforts to control it. Officials estimate that malaria causes up to 409,000 deaths per year. 

To combat the disease and reduce transmission, indoor residual spraying (IRS) is one of the main vector control methods used in many malaria-endemic countries. IRS involves spraying the walls and other surfaces of a building with a residual insecticide that kills mosquitos that land on the sprayed surface, thus preventing transmission of infection. 

Many of these insecticides use pyrethroid chemicals as the primary mode of action, but the spread of vector resistance to insecticides threatens the effectiveness of this tool. 

As a result, the World Health Organisation Global Malaria Programme has outlined a Global Plan for Insecticide Resistance Management (GPIRM) has recommended a rotation of non-pyrethroid insecticides for IRS. 

How does your study tie into this?

Before organizations can introduce new vector control products to the market, the optimal dose and formulation of the active ingredient must be determined. In addition, officials must evaluate the residual efficacy of this dose against the target mosquitoes. 

This study determined the dose and efficacy, including the residual activity, of VECTRON™ T500. This new product contains 50% broflanilide as an active ingredient instead of pyrethroids, and the study aimed to provide evidence of its efficacy against pyrethroid-resistant vectors.

Can you provide an overview of the research and its key findings?

We tested VECTRON™ T500 against susceptible and resistant strains of Anopheles malaria vectors in the laboratory and at field sites in Burkina Faso. 

Firstly, we conducted a laboratory study using blocks of different substrates to determine the most suitable doses for field trials. Secondly, we tested VECTRON™ T500 at two application rates in an experimental field trial using huts with two different wall substrates (mud and concrete) to assess its efficacy against free-flying mosquitoes. 

In the laboratory, VECTRON™ T500 showed residual efficacy (≥80% mortality) for up to 12 months on concrete and mud blocks. In the field trial, VECTRON™ T500 showed high efficacy in mortality in wild mosquitoes. 

These trials have demonstrated the extended residual efficacy of VECTRON™ T500 against pyrethroid-resistant mosquito strains for six months or more and allowed us to define the dose to be used in community trials, i.e., 100 mg/m².

What impact do you hope these findings will have?

VECTRON™ T500 has outstanding efficacy against malaria vector mosquitoes, including strains and populations resistant to pyrethroids and other insecticides. It works on various wall surfaces, including mud, and shows long residual efficacy. 

These findings demonstrate that officials can add VECTRON 500™ to the arsenal of IRS products for use in rotations to control malaria and manage mosquito insecticide resistance, as its action target site differs from current insecticides. 

We hope it will play a key role in reducing malaria transmission, as it is critical to preserve the long-term efficacy of vector control tools for the disease.

Why did you choose to publish your work with Gates Open Research?

We chose to publish with Gates Open Research due to the clear focus on collaborative approaches to research. 

The Platform’s rapid publication model and open peer review procedures facilitated more streamlined and effective collaboration, and we were able to share our results transparently and incorporate reviewer feedback. 

The article was posted online as soon as possible, before peer review, which allowed the broader research community to see the research results quickly. 

For all these reasons, we found Gates Open Research to be well suited to our work.

What’s next for this area of research?

The publication of this study is a crucial step in the product development of VECTRON™ T500. We intend to continue collaborating with the company developing the product to test it on a larger scale in the community. 

After this, we hope it will be prequalified by the World Health Organisation and begin engaging policymakers and key stakeholders on the use of VECTRON™ T500 in malaria control programs. 

Read the full Research Article today on Gates Open Research to dive deeper into the study and findings.

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