How to protect yourself from mosquito bites
Diseases caused by mosquito bites are on the rise. Recently, a New Hampshire resident died of a rare but serious mosquito-borne illness, and infectious-diseases expert Anthony S. Fauci was hospitalized with West Nile virus, which is also transmitted by mosquitoes.
The recent cases have highlighted concerns about mosquito-borne diseases and prompted health authorities to urge more precautions against mosquito bites.
The New Hampshire resident died after contracting eastern equine encephalitis (EEE), which is primarily transmitted by infected mosquitoes and causes brain inflammation. Cases of EEE are circulating in neighboring states, including Massachusetts and Vermont. Some Massachusetts communities have closed parks after dusk, restricted outdoor activities and rescheduled public events.
But choosing an insect repellent to spray on skin and clothes isn’t always easy. The Washington Post asked mosquito experts about the best ways to prevent bites. Here’s what they said.
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Should I be using DEET?
Health experts say the “gold standard” for preventing bug bites is DEET, a chemical repellent developed almost 80 years ago to help the U.S. Army keep mosquitoes away. Despite reassurance from experts about its safety, some people aren’t comfortable spraying DEET on themselves, on their children or while pregnant.
The Centers for Disease Control and Prevention states DEET is safe and effective for those who are pregnant or breastfeeding. The American Academy of Pediatrics recommends that parents use DEET “sparingly” on children younger than 2 years old.
In the 1980s and 1990s, there were documented cases of other adverse health effects in children and adults after using DEET. But subsequent studies have found that DEET “presents little to no risk” when used as instructed.
“If you use this stuff as the directions say, your risk is minuscule of anything negative happening to you, and we’ve been using this thing for a long time,” said Jeffrey R. Bloomquist, a professor at the Emerging Pathogens Institute of the University of Florida.
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What if I don’t want to spray DEET on my skin?
Those who aren’t comfortable applying DEET directly to their skin can spray it on their clothing instead, particularly the cuffs of long-sleeved shirts and pants, said Chris Adigun, a board-certified dermatologist in Chapel Hill, N.C. Just note that the repellent should not be applied under clothing, and it can damage some plastics and synthetic materials.
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What’s the best DEET alternative?
Picaridin, also known as icaridin, is a synthetic repellent registered by the Environmental Protection Agency that resembles a compound found in certain pepper plants. Studies have found a concentration of 20 percent picaridin to be as effective - or even more effective - at repelling mosquitoes as the same concentration of DEET.
The EPA has a list of active ingredients that have been found to be safe and effective as skin-applied insect repellents in addition to DEET and picaridin. They include IR3535, oil of lemon eucalyptus, PMD and 2-undecanone. Consumers can spot products the EPA considers safe and effective by looking for an EPA registration number on the label.
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How long do chemical repellents work?
A 2002 New England Journal of Medicine report looked into how long some repellent products worked against mosquito bites.
A product containing 23.8 percent DEET worked the best, with an average complete protection time of about five hours.
The IR3535-based repellent protected for an average of about 20 minutes.
If you are pregnant, nursing or have young children, be sure to check with your doctor whether these alternatives are safe. Oil of lemon eucalyptus, for example, is not recommended for children younger than 3.
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Do essential oils work to repel mosquitoes?
There is some evidence that certain essential oils can protect against mosquitoes and ticks. But there isn’t enough research into protection times and which concentrations are safe and effective for use on skin.
One study, which tested 20 essential oils against both ticks and mosquitoes, found that clove oil was the most effective against mosquito bites, with a complete protection time of nearly two hours, while cinnamon oil protected for about 80 minutes. Cinnamon oil was the most effective at repelling ticks, with a complete protection time of about two hours.
Citronella oil, a popular ingredient in botanical repellents, protected against mosquito bites for about 30 minutes and ticks for about 15 minutes. The New England Journal of Medicine study also reported a short protection time for several products containing citronella oil - less than 20 minutes.
For the essential-oil experiments, the researchers mixed one part essential oil with nine parts lotion and applied the repellent directly to the skin. But many store-bought products typically use about a 5 percent (or less) concentration of essential oils, said Immo Hansen, senior author of the study and a professor of biology at New Mexico State University who studies vector-borne diseases.
These small concentrations may not be as effective.
Check with your physician or your children’s pediatrician before using products containing essential oils. And don’t try to make your own repellent.
Certain oils may not be safe for frequent and long-term use on skin, said Scott Carroll, president of Carroll-Loye Biological Research, an insect-repellent testing laboratory.
“It’s important that essential oils not be regarded strictly as benign. They won’t be for all individuals,” he said.
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What about ultrasonic or wearable devices?
Wearable ultrasonic devices are rarely successful at repelling mosquitoes, according to Daniel Markowski, technical adviser for the American Mosquito Control Association.
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What else can I do to prevent mosquito bites?
Make sure all window screens in your home are in good shape and have a proper seal. Conduct perimeter checks regularly to make sure there’s no standing water, debris or empty containers that could serve as homes for mosquitoes.
Try to limit outdoor activities during dawn and dusk - when mosquitoes are most active. When you’re outside, cover up. Wear long-sleeved shirts and long pants to protect against mosquitoes, ticks and other insects. Mosquito nets are also a good option to protect babies - just drape them over the stroller, for instance.
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When should I be concerned about a mosquito bite?
When a mosquito bites, people often have a “localized reaction,” with redness and potential swelling, said Marc Siegel, a professor of medicine at George Washington University’s School of Medicine and Health Sciences.
The mark from a mosquito bite is the skin’s reaction to the cocktail of chemicals in the insect’s saliva - including an anesthetic to keep the host from feeling any pain and an anticoagulant to keep the blood flowing. If the bug bite doesn’t go away or gets worse after two to three days, contact your doctor, Siegel said.
West Nile virus is the “most concerning” mosquito-borne virus in the United States, Siegel said. Most people infected with the disease “aren’t even aware” they have it and experience no symptoms. About 1 in 5 people infected with West Nile virus develop a fever, headache, body aches or a rash, among other symptoms, according to the CDC. In rare cases, people can develop encephalitis or meningitis - inflammation of the brain or areas around the brain and spinal cord.
People who experience flu-like symptoms after a mosquito bite should contact their physician.
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