Are mosquito nets becoming less effective against malaria?

A new international study found that insecticide-treated mosquito nets still sharply reduce malaria cases and deaths. It also warned that rising insecticide resistance could weaken their protection and push health systems towards newer tools.

In Short

• Review covers 25 studies across 12 African and Asian countries
• In Asia, treated nets were linked to 68 per cent fewer cases
• African regions saw malaria incidence fall by 29 to 40 per cent

Insecticide-treated mosquito nets, one of the most widely used and affordable tools in the fight against malaria, continue to provide strong protection against the deadly disease. However, a new international study has warned that the growing resistance of mosquitoes to insecticides could undermine the effectiveness of these nets in the future, especially in regions where resistance is already widespread.

The findings come from a comprehensive analysis of 25 studies conducted across 12 countries in Africa and Asia, including India and China. The research, published in the journal Infectious Diseases, examined how well insecticide-treated nets (ITNs) perform in reducing malaria infections and deaths when compared with communities that did not use the nets.

Malaria remains a major public health challenge in many parts of the world. According to global health experts, the disease continues to affect millions of people every year, particularly in tropical and subtropical regions. Insecticide-treated nets have long been considered a cornerstone of malaria prevention because they provide both a physical barrier and a chemical defense against mosquitoes that spread the disease.

The new analysis confirms that these nets remain highly effective. Researchers found that in Asia, the use of ITNs was associated with a 68 per cent reduction in malaria cases and an 18 per cent reduction in malaria-related deaths. In Africa, where malaria burden remains especially high, the nets reduced malaria incidence by between 29 per cent and 40 per cent.

The study reviewed 19 investigations focused on malaria incidence and six studies examining malaria-related mortality. Together, these studies provided evidence that ITNs continue to play a critical role in protecting vulnerable populations and reducing disease transmission across malaria-endemic regions.

However, researchers also highlighted several factors that can affect how well the nets perform. These include differences in mosquito species, varying levels of insecticide resistance, local environmental conditions and the extent to which communities consistently use the nets. Such factors can lead to significant differences in effectiveness from one region to another.

Lead author Dr Gbeminiyi Otolorin, a doctoral researcher at James Cook University in Australia and a veterinary public health clinician at the University of Jos in Nigeria, said the findings should serve both as reassurance and as a warning.

According to Dr Otolorin, the study confirms that insecticide-treated nets remain among the most powerful tools available for malaria control. At the same time, he cautioned that mosquitoes are increasingly developing resistance to commonly used insecticides and are adapting their behaviour. As a result, interventions that work effectively in one area may become less successful in another.

Experts say insecticide resistance occurs when mosquito populations gradually evolve the ability to survive exposure to chemicals that were previously effective in killing them. Over time, this can reduce the protective value of insecticide-based interventions and make disease control efforts more difficult.

To address this growing challenge, researchers have recommended the development and wider use of next-generation mosquito nets. These include pyrethroid-piperonyl butoxide (PBO) nets and other dual-active-ingredient ITNs designed to overcome resistance and improve protection against malaria-carrying mosquitoes.

The authors also stressed the importance of integrating mosquito nets into broader vector-control programmes. Such approaches may include indoor residual spraying, insecticidal wall linings, environmental management and other community-based measures aimed at reducing mosquito populations and limiting disease transmission.

Public health experts believe that continued monitoring of insecticide resistance will be essential for maintaining progress against malaria. Regular surveillance can help authorities identify areas where traditional interventions are becoming less effective and allow them to introduce alternative strategies before outbreaks occur.

The study's findings underline a crucial message: while insecticide-treated nets remain highly effective and continue to save lives, malaria control programmes cannot rely on a single solution indefinitely. Sustained investment in research, innovation and integrated disease-control measures will be necessary to ensure that the gains achieved over the past decades are not lost.

As countries work toward the long-term goal of malaria elimination, researchers say adapting strategies to local conditions and emerging challenges will be key. The continued success of mosquito nets, they argue, will depend not only on widespread use but also on the ability of health systems to stay ahead of evolving mosquito populations.

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