Global analysis exposes wide regional disparities in insecticide-treated net performance

A major analysis of 25 studies across Africa and Asia finds that insecticide-treated nets cut malaria cases by up to 68% - but highlights challenges that threaten to undermine their long-term impact.

The study, published in the peer-reviewed journal Infectious Diseases, confirms that insecticide-treated nets (ITNs) continue to provide strong protection against malaria – but reveals that their effectiveness varies considerably between regions and communities.

These findings suggest that the performance of this relatively simple, low-cost intervention is under pressure - particularly in areas where insecticide resistance is already established.

The researchers warn that without locally adapted control strategies that combine ITNs with other mosquito control measures, progress made over recent decades could be at risk.

"While this study reinforces that ITNs remain one of the most powerful weapons we have against malaria, it is also a warning that we cannot afford to become complacent," says Dr Gbeminiyi Otolorin, a doctoral researcher at James Cook University, Australia, and a veterinary public health clinician and researcher in the Faculty of Veterinary Medicine at the University of Jos, Nigeria.

Mosquitoes are developing resistance and adapting their behaviour – and a tool that works well in one place may already be failing in another. We must continuously monitor, evaluate and tailor our control strategies as we strive towards global elimination of the disease."

Dr. Gbeminiyi Otolorin, James Cook University

Malaria is a life-threatening disease caused by a parasite transmitted to humans through the bites of infected mosquitoes. In 2024, there were an estimated 282 million cases and 610,000 deaths from the infection worldwide. ITNs are among the most widely used and cost-effective tools in malaria prevention – protecting individuals while reducing mosquito populations and cutting transmission across entire communities.

In order to get a better understanding of how much insecticide-treated nets truly reduce malaria illness and death, the researchers analysed data from 25 experimental studies comparing ITN performance with no nets. These included 19 studies examining malaria incidence and six assessing malaria-related deaths, spanning eight African and four Asian countries. Study populations included children under five, pregnant women, households, and entire communities, with follow-up periods ranging from two months to five years.

The findings confirm the strong protective effect of ITNs across these diverse settings. In Asia, ITNs were associated with a 68% reduction in malaria cases and an 18% reduction in malaria-related deaths. In Africa, they reduced malaria incidence by between 29% and 40%.

However, the researchers also identified considerable variation in the effectiveness of ITNs between studies, particularly in Asia. They suggest these differences may be influenced by complex local factors - including mosquito species diversity, patterns of insecticide resistance, and community compliance with net use.

"ITNs are undeniably an effective tool that has saved millions of lives and will continue to do so - but relying on them alone is not enough, particularly in areas with established insecticide resistance," adds Dr Otolorin, a specialist in infectious disease epidemiology.

"Integrated strategies that combine nets with other interventions should now be considered essential – otherwise we risk losing ground in the fight against a disease that still kills hundreds of thousands of people every year."

The paper calls for further research evaluating long-term net durability, community compliance, and insecticide resistance patterns.

"My hope is that this work adds to the existing evidence base supporting malaria control efforts and contributes to ongoing discussions around how insecticide-treated nets can be improved, adapted, and used effectively in communities where malaria prevention remains a priority," Dr Otolorin concludes.