Future US military uniforms could grant protection against disease-carrying mosquitoes by having insect repellent embedded within the fabric itself. Testing by military researchers has shown that specially manufactured nylon fibres can provide slow release of repellents for at least three days, more than the 8-to-12-hour protection provided by spraying common insect repellents such as DEET or picaridin on clothing and skin.
Throughout much of human history, insect-borne disease has often inflicted more casualties on armies than combat 鈥� and there is still good reason for modern militaries to remain vigilant. During a US in 2003, as many as 80 Marines had malaria, with 44 cases requiring medical evacuation flights and the total treatment bill coming to $1.5 million.
A focused on developing fibres for 鈥渋mproved warfighter insect protection鈥� has spent its first year developing a library of nylon fibres that each contain different amounts of DEET and picaridin insect repellents. Those repellents are embedded in the fibre core and surrounded by a sheath layer of nanofibres that can control the repellents鈥� release over time, while also preventing them from being washed out during laundering. Upon release, the repellents provide an almost immediate response, discouraging mosquitoes from landing and feeding.
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The main goal of the programme is to create military uniforms containing the special nylon fibres. 鈥淎 fabric could be composed of different threads of different compositions and blend materials that have either different release profiles 鈥� a fast-release fibre combined with a slow-release fibre right next to each other 鈥� or even different repellents that may have complementary effects,鈥� says at the Naval Research Laboratory in Washington DC.
The technology could have practical advantages over traditional repellent methods. People spraying themselves with insect repellent could miss a spot or might apply it too early before sleeping, so that the chemical protection has worn off when the mosquitoes come to bite, says , formerly at the US Department of Agriculture and currently consulting for the Anastasia Mosquito Control District in St. Augustine, Florida.
鈥淭here are formulations of DEET that go to 12 hours, but that involves a lotion which essentially traps DEET on the skin and allows it to come off over time,鈥� says Bernier. 鈥淚f you have nylon fibres that could do that and release it at a known rate, it鈥檚 far more efficient.鈥�
Lundin and his colleagues measured the evaporation of repellents over time based on the change in the fibres鈥� mass when subjected to different temperatures. They聽have also developed fibres containing the repellent permethrin. US military combat uniforms are already commonly because it can last for about 50 laundry cycles. But there is the potential to extend that lasting protection through the fibre approach, says Lundin. The military researchers are currently conducting live mosquito testing to see which insect repellent mixtures within the fibres provide the best protection. They also plan to run the nylon fibre material through laundry cycles to see how much of the repellents remain over time.
Clothing with built-in protection against insects could find much broader use beyond US military operations. The World Health Organization estimates that there were 627,000 alone in 2020.
鈥淚nsect-repellent fibres obviously have a very broad potential for commercial use in the civilian world,鈥� says Lundin. 鈥淚nsect-borne diseases are significant all over the world.鈥�
