Repellents
You can also help prevent West Nile virus infection by not going outside when mosquitoes are biting, and by using mosquito repellents.
- Most mosquitoes actively search for blood meals in the evening as the sun is going down, and again at dawn. Aedes albopictus, however, bites throughout the day and usually lives near wooded areas filled with underbrush.
- Wear light-colored clothing, long pants, socks, and long-sleeved shirts. Apply repellent to clothing and to a few areas of exposed skin.
A number of repellents are available, but some are more effective than others. In an article appearing in the Annals of Internal Medicine, Mark S. Fradlin, MD, compared several different types of mosquito repellent:
Deet - N,N-diethyl-3-methylbenzamide (DEET)
Deet is the most effective and best studied mosquito repellent currently on the market. DEET was discovered and developed by scientists at the US Department of Agriculture and was patented by the Army in 1946. It is a broad-spectrum repellent that is effective against mosquitoes, biting flies, chiggers, ticks, and fleas. It has a remarkable safety profile after over 40 years of worldwide use, but toxic reactions can occur, especially if the product is misused or overused on babies or young children.
In the US, DEET is available in 5% to 100% concentrations. Higher concentrations provide longer-lasting protection. Unfortunately, no guidelines are available to help consumers decide what concentration is appropriate for their specific needs. Products with 10% to 35% DEET will provide adequate protection under most conditions. Products with more than 50% DEET are best used in conditions where insect biting is intense, and where high temperature and humidity may result in rapid loss of repellent from the skin.
Repellents may be applied directly to the skin or to clothing, screens, tents, or sleeping bags. If DEET-treated garments are stored in a plastic bag between wearings, the repellent effect can last for many weeks.
DEET products can damage plastics such as watch crystals and eyeglasses frames, rayon, spandex, other synthetic fabrics, leather, and painted or varnished surfaces. It does not damage natural fibers such as cotton or wool, and has no effect on nylon.
- USE DEET ACCORDING TO MANUFACTURER'S DIRECTIONS.
- Do not use mixtures with more than 10% DEET on children. Never apply a repellent to an infant.
- Do not use DEET on infants or pregnant women; instead, avoid outdoor activities or use netting/screens to avoid bites.
- Do not allow children to put DEET on themselves.
- Do not apply DEET directly to children. Apply it to your own hands, then put it on the child.
- Avoid putting DEET on children's hands, or near their eyes and mouth.
- Do not spray directly on the face; spray into the hands first, then apply to the face.
- Do not apply to cuts, wounds, or irritated skin.
- Do not use under clothing.
- Do not spray DEET-containing products in enclosed areas.
- DEET is effective for about 4 hours. Avoid prolonged or excessive use of DEET. Use sparingly to cover exposed skin and clothing.
- Wash all treated skin after returning indoors.
- Store DEET out of the reach of children.
Picardin and Lemon Eucalyptus Oil
(April 28, 2005) After years of promoting the chemical DEET as the best defense against West Nile-bearing mosquitoes, the government for the first time is recommending the use of two other insect repellents. Repellents containing the chemical picaridin or the oil of lemon eucalyptus offer "long-lasting protection against mosquito bites," the Centers for Disease Control and Prevention said, adding that repellents with DEET remain on the agency's recommendation list. Both products have been available elsewhere in the world, including Europe and Australia, since the 1980s. Consumers tend to like picaridin repellents because they are more pleasant to the skin and don't have the odor that DEET repellents have. And oil of lemon eucalyptus is a natural ingredient, which appeals to those who don't like the thought of putting chemicals on their skin, said Angela Proctor, a product manager for the Cutter line of insect repellents by Spectrum Brands. Spectrum Brands introduced a picaridin-based repellent in January (2005) -- Cutter Advanced (www.cutterinsectrepellent.com) -- and it has been marketing a repellent with oil of lemon eucalyptus since 2002. The products provide four and six hours of protection, respectively, Proctor said.