How mosquito nets help prevent malaria
Understanding how mosquito nets work, why they matter and how they continue to evolve
Modern progress against an ancient disease
Malaria is one of the oldest known human diseases, with cases dating back several millennia. Although it has been eliminated across much of Europe and North America, more than 80 countries continue to face malaria, with the vast majority of cases and deaths occurring in Africa.
The disease is caused by Plasmodium parasites and spreads through the bite of an infected female Anopheles mosquito. Young children and pregnant women are at greatest risk of severe illness and death.
Most malaria-carrying mosquitoes bite at night, often while people are asleep. This is one reason why mosquito nets remain an important tool for malaria protection.
How mosquito nets protect against malaria
Insecticide-treated nets (ITNs) help reduce malaria transmission in several ways:
A physical barrier. The mesh creates a barrier between people and mosquitoes during the night, when most malaria transmission occurs.
Insecticidal action. The insecticide in the netting kills or disables mosquitoes that land on the net while searching for a blood meal. Unlike an untreated net, an ITN provides both a physical and chemical form of protection.
Community protection. When a large proportion of a community sleeps under ITNs, fewer mosquitoes survive to spread malaria. This lowers transmission across the wider community, including people who are not under sleeping under a net on a given night.
This broader community effect is why malaria prevention programmes aim for high levels of net coverage as well as consistent use. See what the evidence shows about coverage.
From ancient nets to long-lasting protection
Physical barriers against biting insects have been used for centuries. During the twentieth century, bed nets became an established tool for preventing mosquito-borne diseases in both civilian and military settings.
The 1980s saw the introduction of insecticide-treated nets, which combined a physical barrier with insecticidal action. However, these nets required retreatment every 6 to 12 months, making large-scale implementation difficult and costly.
Drawing on expertise in material science and textile engineering, Vestergaard contributed to the development of long-lasting insecticide-treated nets (LLINs), designed to maintain their effectiveness for years without retreatment. By the early 2000s, LLINs, alongside other vector control interventions, had become an important component of malaria control programmes.
Types of mosquito nets
Mosquito nets have evolved over time as malaria programmes have responded to changing public health needs.
Net type | How it works | Example |
|---|---|---|
Untreated net | Physical barrier only | – |
Conventional ITN | Barrier plus insecticide; needs retreatment every 6–12 months | - |
Long-lasting ITN (LLIN), pyrethroid-only | Insecticide built into the fibre; lasts for years without retreatment | |
Pyrethroid-PBO net | Adds a synergist (PBO) that weakens mosquitoes' resistance defences | |
Dual-active ingredient net | Combines a pyrethroid with a second insecticide that works differently |
ITN or LLIN? Most insecticide-treated nets used today are long-lasting insecticide-treated nets (LLINs). For this reason, the term insecticide-treated net (ITN) is often used as a general term for both.
Insecticide resistance and mosquito net effectiveness
For many years, most ITNs relied on a single class of pyrethroids, a class of insecticides widely used in malaria vector control. Over time, some mosquito populations have become less susceptible to these insecticides, a phenomenon known as insecticide resistance.
Insecticide resistance does not eliminate the protective value of mosquito nets. The physical barrier remains effective, and insecticide-treated nets continue to reduce malaria transmission. However, resistance can reduce the effectiveness of insecticides, leading to the development of new net technologies designed to address this challenge:
Pyrethroid-PBO nets combine a compound that blocks the mosquito's internal defences, so the pyrethroid works again
Dual-active-ingredient nets combine a pyrethroid with a second insecticide that works through a different mode of action, helping to improve the effectiveness against resistant mosquito populations.
Resistance monitoring, research partnerships and product development help inform the design of mosquito nets for areas where insecticide resistance is present. This includes collaborations such as the Vestergaard–Noguchi Vector Labs, and invests in innovation and product development to stay ahead.
Learn more about insecticide resistance and ITN effectiveness.
Getting the most from a mosquito net
Consistent and correct use is important for a mosquito net to provide effective protection.
Sleep under it every night, all year round, not only in the rainy season. Children under five and pregnant women should always sleep under a net.
Hang it properly. The net should cover the whole sleeping area and be tucked under the mattress or mat so there are no gaps.
Wash gently and not too often. Use mild soap and cool water, and dry the net in the shade. Frequent washing and direct sunlight can reduce insecticide over time.
Repair holes quickly by stitching or tying them closed.
Replace worn nets when they have large holes or are damaged beyond repair.
User experience can also influence consistent net use. Research suggests that net material may affect user preferences, with some users favouring softer polyester nets over stiffer polyethylene alternatives. Vestergaard uses polyester across its PermaNet portfolio to support user acceptance and consistent use.
Two decades of PermaNet in malaria prevention
For more than 20 years, PermaNe ITNs nets have supported malaria prevention efforts in countries affected by malaria. Vestergaard's portfolio of WHO-prequalified ITNs includes standard pyrethroid nets and next-generation nets designed for areas with insecticide resistance.
More than 1 billion PermaNet nets distributed worldwide. Since 2000, malaria interventions have helped avert an estimated 2.2 billion cases and 12.7 million deaths globally (WHO World Malaria Report 2024).
Frequently asked questions
Do mosquito nets prevent malaria? Yes. Sleeping under an insecticide-treated net is one of the most effective ways to prevent malaria. The net blocks mosquitoes, and the insecticide kills or disables those that land on it.
What is the difference between an ITN and an LLIN? An LLIN is a long-lasting ITN, with insecticide that lasts for years without retreatment. Most ITNs distributed today are LLINs, which is why the term ITN is often used as a general term for both.
How long does a mosquito net last? ITNs are designed to stay effective for about three years of regular use. Real-world lifespan depends on care, washing, and household conditions.
Are insecticide-treated nets safe for babies and pregnant women? Yes. WHO-prequalified nets are evaluated for safety, and young children and pregnant women are the groups that benefit most from sleeping under one.
Why are some mosquitoes resistant to insecticides? Repeated exposure to the same insecticide allows mosquitoes that survive it to multiply. Next-generation nets counter this with synergists or a second insecticide.
Why does net material matter? User preferences can influence how consistently mosquito nets are used. Research suggests that net material may affect comfort and acceptability, which in turn may contribute to regular use.