Mosquito nets treated with insecticide are an important measure for preventing malaria. But, the poison can wash out. The "LifeNet," which has mosquito-repelling chemicals deep within its fibers, might be the solution.
According to the World Health Organization (WHO), a million people die each year from malaria. Some 90 percent of these fatalities occur in Africa, where the illness is at its worst.
Experts agree that widespread use of mosquito nets impregnated with pesticide offers one of the most effective modes of protection against spread of the disease.
It's especially important to consistently use mosquito bed nets with small children, as every second malaria victim worldwide is under five years old. Young children often go to sleep early, at dusk, around the same time as the malaria-carrying nocturnal Anopheles mosquito becomes active.
Every single night
Jürgen May, a professor at the Bernhard-Nocht Institute for Tropical Medicine in Hamburg, also sees mosquito nets as the key to fighting malaria.
It's also important that using the nets for sleeping areas become a part of a daily routine, May says. "You can really achieve a lot with bed nets, but they have to be used correctly, regularly treated with insecticide and free of holes."
Experience shows that once they've been used for some time, mosquito nets can become dirty and unsightly. Nets made with soft fibers can be washed, but this can be problematic as such nets tear quite easily. Although nets made of stiff fibers are more durable, they're also harder to clean.
Most importantly, normally nets would have to be repeatedly treated with pesticide to maintain effectiveness against mosquitoes. Washing them removes the substance from the fabric.
Deep in the fiber
Frederic Baur, an agronomist with Bayer CropScience, thinks he has found the solution to the problem. "Above all, the insecticide should be built into the fiber," Baur told DW. "The challenge was to create a net with softness and durability."
Nets with both qualities would make it more likely for people living in affected malaria regions to actually use them, he added.
The Bayer lab developed a polypropylene fiber that was especially durable considering it was so soft. Similar to sporting apparel that incorporates nano-silver ions to prevent sweat, insecticide is added to the plastic before it's spun into fibers.
A big challenge was that insecticide is particularly sensitive to heat - and in order to spin polypropylene into fibers, it must be warmed up quite a bit. But the lab managed to overcome this challenge, and the new fiber impregnated with the insecticide deltamethrin retains its insecticidal properties for an extended period of time.
"The net fiber very gradually releases the insecticide," Baur said. "When the insecticide comes off the surface through washing or normal wear, new insecticide comes out from inside."
Such deep impregnation allows for nets that can be washed more than 30 times yet still have effective levels of the poison, Baur says.
Safer than spray
The insecticide deltamethrin is very powerful and critics say it is damaging to human health and the environment. But, in contrast to insecticide which is sprayed into the air, the impregnated nets are far safer for adults and young children, say the manufacturers.
Baur said his company ran comprehensive studies on health effects. "The quantity of active ingredient is so low that it has practically no effect on humans or other mammals. Yet, it's highly effective against mosquitoes," he said.
Bayer has called its deep-treated nets "LifeNet" and made it a goal to produce millions worldwide. If broadly distributed, such nets will hopefully help both malaria sufferers and at-risk locals finally sleep peacefully.