Durability and Efficacy of Insecticide-Treated Nets in Malaria Control

Insecticide-treated nets remain a cornerstone of malaria prevention, combining physical barrier effects with chemical activity to reduce human–vector contact. The long-lasting insecticidal net (LLIN) concept seeks to maintain both structural integrity and insecticidal potency for at least three years under field conditions. However, net performance is influenced by a constellation of factors: physical wear and tear, insecticide decay, user behaviours and vector adaptation. Studies have repeatedly shown that attrition through disposal or repurposing, and hole formation from routine handling or environmental stressors, can curtail functional survival well below the assumed lifespan. Concurrently, variation in residual insecticide concentration and novel behavioural responses by mosquitoes may affect protective efficacy. Optimising net design, material strength and community engagement on care and repair are therefore essential to sustain universal coverage and to maximise impact on malaria transmission globally.

Research from Nature Portfolio

Advanced three-dimensional video tracking of Anopheles gambiae interactions with permethrin-treated nets has revealed unexpectedly higher passage rates through holed nets, attributed to insecticide-induced agitation that increases flight trajectories and hole encounters. This finding underscores the complexity of behavioural modes of action and suggests that net integrity and pore size distribution require re-evaluation alongside chemical formulation. In parallel, spatially-resolved mapping of insecticide-treated net access, use and nets-per-capita across high-burden African countries from 2000–2020 has demonstrated that nets are discarded faster than policy models predict, driven by low physical durability, distribution logistics and social messaging. These high-resolution time series support policy refinement for targeted allocations, improved material specifications and more realistic serviceable-life assumptions.

Durability and Efficacy of Insecticide-Treated Nets in Malaria Control publication trend

The graph below shows the total number of articles in durability and efficacy of insecticide-treated nets in malaria control across all publications each year (not limited to Nature Index journals).

Technical terms

Long-Lasting Insecticidal Net (LLIN): A mosquito net factory-treated with insecticide designed to retain effective levels of active ingredient and physical integrity for at least three years under field conditions.

Functional survival: The duration during which an LLIN remains present in a household, maintains requisite fabric integrity and delivers insecticidal activity above minimum thresholds.

Attrition: The loss of nets from use due to disposal, repurposing, damage or other removal from the protective pool.

Bio-efficacy: The mosquito-killing or –knock-down performance of a treated net, typically measured by standard assays that record immediate knock-down and 24-hour mortality.

Proportional Hole Index (pHI): A weighted assessment of net fabric integrity that quantifies hole number and size to categorise nets as serviceable or in need of replacement.

References

1. 3D video tracking analysis reveals that mosquitoes pass more likely through holes in permethrin-treated than in untreated nets. Scientific Reports (2024).
2. Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000-2020. Nature Communications (2021).
3. Durability of long-lasting insecticidal nets (LLINs) in Ethiopia. Malaria Journal (2023).
4. Comparative functional survival and equivalent annual cost of 3 long-lasting insecticidal net (LLIN) products in Tanzania: A randomised trial with 3-year follow up. PLOS Medicine (2020).
5. Bioefficacy and durability of Olyset® Plus, a permethrin and piperonyl butoxide-treated insecticidal net in a 3-year long trial in Kenya. Infectious Diseases of Poverty (2021).