West Nile Virus - Insect Repellent Use
Q. Why should I use insect repellent?
A. Insect repellents help people reduce their exposure to mosquito bites that may carry potentially serious viruses such as West Nile virus, and allow them to continue to play and work outdoors.
Q. When should I use mosquito repellent?
A. Apply repellent when you are going to be outdoors and will be at risk for getting bitten by mosquitoes.
Q. What time of day should I wear mosquito repellent?
A. Many of the mosquitoes that carry the West Nile virus are especially likely to bite around dusk and dawn. If you are outdoors around these times of the day, it is important to apply repellent. In many parts of the country, there are mosquitoes that also bite during the day, and these mosquitoes have also been found to carry the West Nile virus. The safest decision is to apply repellent whenever you are outdoors.
Q. How often should repellent be reapplied?
A. Follow the directions on the product you are using in order to determine how frequently you need to reapply repellent. As a general rule, repellents containing a higher concentration of active ingredient provide longer-lasting protection.
Q. How does mosquito repellent work?
A. Mosquitoes eat plant juices and flower nectar for energy. Female mosquitoes bite people and animals because they need the protein found in blood to help make their eggs.
Mosquitoes are attracted to people by our skin odors and carbon dioxide from our breath. When a mosquito gets close to a person, DEET and some other repellents jam the mosquito's sensors and confuse the mosquito so it is unable to land and bite the person successfully. DEET does not kill mosquitoes; it just makes them unable to locate us. Repellents are effective only at short distances from the treated surface, so you may still see mosquitoes flying nearby. As long as you are not getting bitten, there is no reason to apply more DEET.
Q. Which mosquito repellent works the best?
A. The most effective repellents contain DEET (N,N-diethyl-m-toluamide) which is an ingredient used to repel pests like mosquitoes and ticks. DEET has been tested against a variety of biting insects and has been shown to be very effective. Products that contain at least 35% DEET are the most effective for adults. There is no additional protection from products containing more than 50% DEET.
Q. Why does CDC recommend using DEET?
A. DEET is the most effective and best-studied insect repellent available. (Fradin, 1998) Studies using humans and mosquitoes report that only products containing DEET offer long-lasting protection after a single application.
Q. Are non-DEET repellents effective (e.g. Skin-So-Soft, plant-based repellents)?
A. Some non-DEET repellent products which are intended to be applied directly to skin also provide some protection from mosquito bites. However, studies have suggested that other products do not offer the same level of protection, or that protection does not last as long as products containing DEET. A soybean-oil-based product has been shown to provide protection for a period of time similar to a product with a low concentration of DEET (4.75%)
People should choose a repellent that they will be likely to use consistently and that will provide sufficient protection for the amount of time that they will be spending outdoors. Product labels often indicate the length of time that protection that can be expected from a product. Persons who are concerned about using DEET may wish to consult their health care provider for advice. The National Pesticide Information Center (NPIC) can also provide information through a toll-free number, 1-800-858-7378 or http://npic.orst.edu.
Q. I'm confused. None of the products in the store say "DEET."
A. Most insect repellents that are available in stores are labeled with the chemical name for DEET. Look for N,N-diethyl-m-toluamide or, sometimes, N,N-diethly-3-methylbenamide.
Using Repellents Safely
Q. Is DEET safe?
A. Because DEET is so widely used, a great deal of testing has been done. When manufacturers seek registration with the U.S. Environmental Protection Agency (EPA) for products such as DEET, laboratory testing regarding both short-term and long-term health effects must be carried out. Over the long history of DEET use, relatively few confirmed incidents of toxic reactions to DEET have occurred when the product is used properly (From the National Pesticide Information Center [NPIC], EPA re-registration eligibility decision.)
Q. What are some general considerations to remember in order to use products containing DEET safely?
A. Always follow the recommendations appearing on the product label.
- Use enough repellent to cover exposed skin or clothing. Don't apply repellent to skin that is under clothing. Avoid over application.
- Do not apply repellent to cuts, wounds, or irritated skin.
- After returning indoors, wash treated skin with soap and water.
- Do not spray aerosol or pump products in enclosed areas.
- Do not apply aerosol or pump products directly to your face. Spray your hands and then rub them carefully over the face, avoiding eyes and mouth.
Q. How should products containing DEET be used on children?
A. No definitive studies exist in the scientific literature about what concentration of DEET is safe for children. The American Academy of Pediatrics has recommended that a cautious approach is to use products with a low concentration of DEET, 10% or less, on children. Some guidelines cite that it is acceptable to use repellents containing DEET on children over 2 years of age. Other experts suggest that it is acceptable to apply repellent with DEET to infants over 2 months old. Repellent products that do not contain DEET are not likely to offer the same degree of protection from mosquito bites as products containing DEET.
Parents should choose the type and concentration of repellent to be used by taking into account the amount of time that a child will be outdoors, exposure to mosquitoes, and the risk of mosquito-transmitted disease in the area. Non-DEET repellents have not necessarily been as thoroughly studied as DEET, may not be safer for use on children and are generally not as effective as DEET-containing products. Persons who are concerned about using DEET or other products on children may wish to consult their health care provider for advice. The National Pesticide Information Center (NPIC) can also provide information through a toll-free number, 1-800-858-7378 or http://npic.orst.edu.
Always follow the recommendations appearing on the product label when using repellent.
- When using repellent on a child, apply it to your own hands and then rub them on your child. Avoid children's eyes and mouth and use it sparingly around their ears.
- Do not apply repellent to children's hands. (Children tend to put their hands in their mouths.)
- Do not allow young children to apply insect repellent to themselves; have an adult do it for them.
- Do not apply repellent to skin under clothing. If repellent is applied to clothing, wash treated clothing before wearing again.
Using repellents on the skin is not the only way to avoid mosquito bites.
Q. Is DEET safe for pregnant or nursing women?
A. There are no reported adverse events following use of repellents containing DEET in pregnant or breastfeeding women.
Q. Are there any risks due to using repellents containing DEET?
A. Use of these products may cause skin reactions in rare cases. If you suspect a reaction to this product, discontinue use, wash the treated skin, and call your local poison control center. If you go to a doctor, take the product with you.
Repellents and Schools
Q. Should parents spray insect repellent on their children before they go to school?
A. Whether children spend time outside during the school day should determine the need for applying repellent. Because most schools in the United States have air conditioning, children's exposure to mosquitoes during the school day is not likely to be high. If children will be spending time outdoors (for example, in recreational activities, walking to and from school), parents may wish to apply repellent. Mosquito repellent containing DEET is the most effective in providing long-lasting protection from mosquito bites.
Q. Should children be given repellent to use during the day?
A. The age and maturity of the child should be taken into account before giving repellent to children for their own use. As with many other chemicals, care should be taken that DEET is not misused or swallowed. Parents should find out if a child will be outside during the school day, and should discuss proper use of the product with their children. Parents should also consult local officials to obtain policies and procedures specific to bringing repellent to school.
Q. Where can I get more information about repellents?
A. For more information about using repellents safely please consult the EPA Web site: http://www.epa.gov or consult the National Pesticide Information Center, which is cooperatively sponsored by Oregon State University and the US EPA. NPIC can be reached at http://npic.orst.edu or 1-800-858-7378
Some info was courtesy of Fradin and Day, 2002.