West Nile virus, prevent encephalitis, DEET safe use

We provide this free health resource to visitors of the Community Room of SeniorSSuperStoreS in an effort to keep baby boomers, seniors and the elderly informed of matters that can affect their lifestyle.

The onset of summer, combined with a relatively wet winter and spring, makes summer a time of greater than normal concern for the West Nile virus, although the disease has been around in the U.S. for a number of years. The information in this article, drawn primarily from the Centers for Disease Control website (www.CDC.gov) is intended to summarize what you have heard and read regarding the precautions we should take to avoid the virus.

Prevention of West Nile Virus:

The best prevention is to avoid mosquito bites!

Human illness from West Nile virus is rare, even in areas where the virus has been reported. The chance that any one person is going to become ill from a mosquito bite is low. You can further reduce your chances of becoming ill by protecting yourself from mosquito bites. To avoid mosquito bites:

Apply insect repellent containing DEET (N,N-diethyl-meta-toluamide) when you're outdoors. A source of information about pesticides and repellents is the National Pesticide Information Center, which also operates a toll-free information line: 1-800-858-7378.

When possible, wear long-sleeved clothes and long pants treated with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.

Do not apply repellents containing permethrin directly to exposed skin. If you spray your clothing, there is no need to spray repellent containing DEET on the skin under your clothing.

Consider staying indoors at dawn, dusk, and in the early evening, which are peak mosquito biting times.

Limit the number of places available for mosquitos to lay their eggs by eliminating standing water sources from around your home.

Check to see if there is an organized mosquito control program in your area. If no program exists, work with your local government officials to establish a program. The American Mosquito Control Association can provide advice, and their book Organization for Mosquito Control is a useful reference.

Symptoms of West Nile Virus:

West Nile virus is spread by the bite of an infected mosquito, and it can infect people, horses, many types of birds, and some other animals.

Most people who become infected with West Nile virus will have either no symptoms or only mild ones. However, on rare occasions, West Nile virus infection can result in a severe and sometimes fatal illness known as West Nile encephalitis (an inflammation of the brain). The risk of severe disease is higher for persons 50 years of age and older! It is unknown if immunocompromised persons are at increased risk for WNV disease.

There is no evidence to suggest that West Nile virus can be spread from person to person or from animal to person.

If you should contract the disease, note that the CDC is not a hospital or clinical facility; they do not see patients and are unable to diagnose your illness, provide treatment, prescribe medication, or refer you to specialists.

If you have a medical emergency, contacting CDC is not the proper way to get immediate help. If you are a patient, please see your health care provider or the nearest emergency room. If you are a health care provider, please contact your state epidemiologist or local health department.

Reporting Dead Birds:

Dead birds in an area may mean that West Nile virus is circulating between the birds and the mosquitoes in that area. Over 110 species of birds are known to have been infected with West Nile virus. Although birds, particularly crows and jays, infected with WN virus can die or become ill, most infected birds do survive.

The public can play an important role in monitoring West Nile virus through reporting dead birds to state and local health departments. States have different policies for collecting and testing birds, so contact your local Health Department to find out how to report dead birds in your area.

Because CDC is a federal agency, they do not deal directly with the reporting of dead birds. State and local health departments are responsible for initiating these investigations; they report their findings to CDC.

Answers to Frequent Questions About the West Nile Virus:

Q. What can I do to reduce my risk of becoming infected with West Nile virus?
A. Here are preventive measures to take:

Apply insect repellent sparingly to exposed skin. The more DEET a repellent contains the longer time it can protect you from mosquito bites. A higher percentage of DEET in a repellent does not mean that your protection is better - just that it will last longer. DEET concentrations higher than 50% do not increase the length of protection. Choose a repellent that provides protection for the amount of time that you will be outdoors.

Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.

Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer's DIRECTIONS FOR USE, as printed on the product.

Spray clothing with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing. Do not apply repellents containing permethrin directly to exposed skin. If you spray your clothing, there is no need to spray repellent containing DEET on the skin under your clothing.

When possible, wear long-sleeved shirts and long pants whenever you are outdoors.

Place mosquito netting over infant carriers when you are outdoors with infants.

Consider staying indoors at dawn, dusk, and in the early evening, which are peak mosquito biting times. 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.

Install or repair window and door screens so that mosquitoes cannot get indoors.

To avoid helping mosquitoes breed in your environment, drain standing water. Routinely empty water from flower pots, pet bowls, clogged rain gutters, swimming pool covers, discarded tires, buckets, barrels, cans, and other items that collect water in which mosquitoes can lay eggs.

Note: Vitamin B and "ultrasonic" devices are NOT effective in preventing mosquito bites, according to the CDC.

Q. Is there a vaccine against West Nile encephalitis?
A. No, but several companies are working towards developing a vaccine.

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. Sweating, perspiration or getting wet may mean that you need to re-apply repellent more frequently. If you are not being bitten, it is not necessary to re-apply repellent. Repellents containing a higher concentration of active ingredient (such as DEET) provide longer-lasting protection.

Q. Should I wear repellent while I am indoors?
A. Probably not. If mosquitoes are biting you while you are indoors, there are probably better ways to prevent these bites instead of wearing repellent all the time. Check window and door screens for holes that may be allowing mosquitoes inside. If your house or apartment does not have screens, a quick solution may be to staple or tack screening (available from a hardware store) across the windows. In some areas community programs can help older citizens or others who need assistance.

Q. How does mosquito repellent work?
A. Only female mosquitoes bite people and animals, and they do so because they need the protein found in blood to help develop their eggs. Mosquitoes are attracted to people by skin odors and carbon dioxide from breath. Many repellents contain a chemical, N,N-diethyl-m-toluamide (DEET), which repels the mosquito, making the person unattractive for feeding. 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. The more DEET a repellent contains the longer time it can protect you from mosquito bites. A higher percentage of DEET in a repellent does not mean that your protection is better - just that it will last longer. DEET concentrations higher than 50% do not increase the length of protection.

Q. How does the percentage of DEET in a product relate to the amount of protection it gives?
A. Based on a recent study:

A product containing 23.8% DEET provided an average of 5 hours of protection from mosquito bites.

A product containing 20% DEET provided almost 4 hours of protection

A product with 6.65% DEET provided almost 2 hours of protection

Products with 4.75% DEET and 2% soybean oil were both able to provide roughly 1 and a half hour of protection.

Choose a repellent that provides protection for the amount of time that you will be outdoors. A higher percentage of DEET should be used if you will be outdoors for several hours while a lower percentage of DEET can be used if time outdoors will be limited. You can also re-apply a product if you are outdoors for a longer time than expected and start to be bitten by mosquitoes.

Q. Why does CDC recommend using DEET?
A. DEET is the most effective and best-studied insect repellent available. 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.

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 npic.orst.edu.

Q. I'm confused. None of the products in the store says "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. Choose a repellent that offers appropriate protection for the amount of time you will be outdoors. A higher percentage of DEET should be used if you will be outdoors for several hours while a lower percentage of DEET can be used if time outdoors will be limited.

Q. Is DEET safe?
A. Yes, products containing DEET are very safe when used according to the directions. 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, very few confirmed incidents of toxic reactions to DEET have occurred when the product is used properly. (From the National Pesticide Information Center; see npic.orst.edu/factsheets/DEETgen.pdf.)

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. In lieu of clear recommendations, or in addition, remember the following:

Use enough repellent to cover exposed skin or clothing. Don't apply repellent to skin that is under clothing. Heavy application is not necessary to achieve protection.

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 aged 2 - 12. Most 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 low concentrations of DEET to infants over 2 months old. It is recommended that for children under 2 years of age only one application per day of repellent containing DEET should be used.

Repellent products that do not contain DEET are not likely to offer the same degree of protection from mosquito bites as products containing DEET. Non-DEET repellents have not necessarily been as thoroughly studied as DEET, and may not be safer for use on children.

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. 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 npic.orst.edu.

Always follow the recommendations appearing on the product label when using repellent. In lieu of clear recommendations, or in addition, remember the following:

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. Keep repellents out of reach of children.

Do not apply repellent to skin under clothing. If repellent is applied to clothing, wash treated clothing before wearing again.

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. There is a new national number to reach a Poison Control Center near you: 1-800-222-1222.

If you go to a doctor, take the product with you. Cases of serious reactions to products containing DEET have been related to misuse of the product, such as swallowing, using over broken skin, and using for multiple days without washing skin in between use, for example. Always follow the instructions on the product label.