Watch out! Mosquito bites from the Aedes aegypti spread dengue fever, chikungunya, Zika, yellow fever, and other diseases

Mosquito bites can be deadly, but new clothing and wristbands impregnated with repellents and insecticides could help keep mosquitoes at bay. These new ‘wearables’ may do more than simply offer protection against mosquito bites; they could also reduce mosquito numbers near to their wearers.

Aedes aegypti mosquitoes, which transmit dengue fever and Zika, most commonly feed at dawn and dusk. The mosquito bites, both indoors or out, particularly in shady areas, or when the weather is cloudy. Researchers say effective ‘wearable’ protection offers a convenient way to stop mosquitoes from biting.

Image of Dr. Logan courtesy of ARCTEC

“What’s really needed is some form of protection while you’re on the move,” says Dr. James Logan, director of arctec at the London School of Hygiene and Tropical Medicine (LSHTM). “After all, you don’t just need protection from Aedes aegypti in your home and your garden; you need it at school or when working outside, for instance.”

Developing novel personal protection products

Rebranded as “ARCTEC” in 2010, the arthropod control material testing laboratory has been operating at LSHTM for more than 20 years. Dr. Logan and his team are currently exploiting new technologies and collaborations to develop new wearable protection solutions. By using these to change the vector’s behavior, they hope to protect the wearer from Aedes aegypti bites and, in doing so, help reduce the spread of dengue.

But finding acceptable forms of wearable personal protection can be challenging. Despite being advised to wear long-sleeved clothing and long trousers when outdoors during the day and evening to avoid mosquito bites, many people living in dengue-endemic regions may be actually more likely to wear shorts and short sleeves a lot of the time – which is not surprising considering that the weather is hot and humid.

Impregnated clothing reduces mosquito numbers

ARCTEC was recently involved in the DengueTools research project, taking a key role in identifying strategies for reducing dengue transmission in children when they’re in school. This project included a blind study aimed at investigating whether school uniforms impregnated with permethrin, a synthetic insecticide, offered a viable approach to protecting children.

“ARCTEC led the development of the clothing impregnation technology,” reveals Dr. Logan. “We worked with a number of companies to investigate how well their solutions worked.”

Unfortunately, the insecticide – permethrin – washed out of the school uniforms earlier than anticipated. Nevertheless, the research project allowed the team to answer another very important question: how well does permethrin prevent bites?

“We already knew that clothing impregnated with permethrin can kill mosquitoes, but we didn’t know how well it would stop the mosquitoes from biting,” explains Dr. Logan. “The mosquitoes might still land and bite before they die, for instance.”

The study found that, before the permethrin had washed out, the impregnated clothing did provide very good protection against mosquito bites. More than that, it found the clothing also significantly reduced mosquito numbers in and around the school.

“We might also be able to use the clothing, not just to protect people, but also to influence local populations of mosquitoes around a school, home, workplace or anywhere else,” adds Dr. Logan.

Counting mosquito bites

The team is now continuing their studies back at ARCTEC’s London laboratory where they are releasing mosquitoes into their free-flight rooms. These rooms allow the team to evaluate products in a natural setting. Volunteers sit in these rooms with their trousers rolled up and their arms bared waiting for mosquitoes to bite – or not.

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In this instance, the team is using these rooms to carry out unique research into the level of protection provided against mosquito bites by impregnated clothing when the wearer doesn’t have long sleeves and long trousers. “We measure how many mosquitoes land on a person and how many mosquito bites they get,” reveals Dr. Logan. “We compare people wearing long sleeves and long trousers with people wearing short sleeves and short trousers.”

Evaluating insect repellent products. Image courtesy of ARCTEC

The clothing is showing great potential. It offers someone wearing a t-shirt and shorts greater than 50 percent protection against bites from Aedes aegypti – which is very significant.

Testing out in the field

The team is currently developing a wide range of wearable protection technologies, from wristbands to different types of clothing. For the next phase, ARCTEC will work with companies that have developed unique ways of keeping the permethrin in the clothing. Their aim? They are looking to develop protection that might, in some cases, last up to four to five months.

“We’re making good progress in keeping actives in the wearable technology for longer,” comments Dr. Logan. “We’re also working with companies who are adding other active ingredients that have a better repellency than permethrin.”

Learn how

The next stage will see Dr. Logan and his team go back to into the field to trial their enhanced clothing. They will need to evaluate how it well works in the real world: what effect UV lights, washing, tumble drying, and ironing have, amongst other things. All these factors need to be fully understood before an end product can be developed.

Maximizing uptake

Focus group studies, in Columbia as a starting point, will give the team some insight into which types of wearable technology might be acceptable for different populations of people: pregnant women, school children with different types of uniforms and outdoor workers, for example.

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Dr. Logan explains why this is so important: “We want to get a feel for what those technologies should look like, so we can maximize uptake.”

The output from the studies will be fed into the eventual design to help with initial prototypes. A user acceptability study will then confirm how many people will use the product and reveal how it could be improved. This research will ensure the final product is accepted and likely to be used.

ARCTEC’s wearable protection technologies will offer dengue-endemic communities a welcome additional tool to help them combat the disease. Combining them with improved surveillance, enhanced vector control, vaccination, community participation, cross-industry collaboration and more, will help in the fight against dengue fever.

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