Tips on how to protect against mosquitoes causing West Nile virus.
Summertime, and the livin' is easy? Well, maybe, but it's also the season that offers the greatest chance of catching West Nile virus, a mosquito-borne infection that can cause encephalitis.
According to the Centers for Disease Control & Prevention, most people who become infected with West Nile virus will have either mild symptoms or none at all. On rare occasions, West Nile virus can result in severe and sometimes fatal illness.
It is estimated that 20% of the people who become infected with the virus will develop West Nile fever: mild symptoms, including fever, headache, and body aches, occasionally with a skin rash on the trunk of the body, and swollen lymph glands.
The symptoms of severe infection (West Nile encephalitis or meningitis) include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. It is estimated that one in 150 persons infected with the West Nile virus will develop the more severe form of the disease.
The incubation period in humans is usually three to 14 days. Symptoms of mild disease will generally last a few days. Symptoms of severe disease may last several weeks, although neurological effects may be permanent.
Patients who want to reduce their exposure to mosquito bites that may carry the West Nile virus can turn to insect repellents for prevention.
Here's what pharmacists should tell their patients who ask for information about the proper use of repellents:
If you are outdoors around dusk or dawn, it is important to apply repellent because that is when many mosquitoes carrying the virus are likely to bite. In many parts of the country, however, there are mosquitoes that also bite during the day. The safest decision is to apply repellent whenever you are outdoors.
If you sweat or get wet, you may need to reapply repellent more frequently. If you are not getting bitten, it is not necessary to reapply repellent.
According to David Sullivan, a malarial researcher at Johns Hopkins Bloomberg School of Health, Baltimore, soybean oil is one of the most effective natural mosquito repellents available. A product containing 2% soy oil lasts about three hours. Other natural repellents are cedar oil, peppermint oil, lemon grass oil, and citronella.
N,N-diethyl-meta-toluamide, or DEET, is an insect repellent that can reduce the risk of mosquito bites, but it must be used with caution. Use of these products may cause skin reactions in rare cases. If you suspect a reaction, discontinue use, wash the treated skin, and call your local poison control center. The new national number to reach the local center near you is 1 (800) 222-1222.
The CDC states that DEET is the most effective and best-studied insect repellent available. Some non-DEET repellent products applied directly to skin also provide some protection from mosquito bites. However, studies have suggested that other products don't offer the same level or duration of protection as the DEET-containing products. Repellents containing a higher concentration of active ingredient (such as DEET) provide longer lasting protection.
The CDC offers the following recommendations about using DEET:
Always follow directions and recommendations on the product label.
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 your face, avoiding eyes and mouth.
Since no definitive studies exist 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 two to 12. Most guidelines indicate that it is acceptable to use repellents containing DEET on children over two years of age. Other experts suggest that it is acceptable to apply repellent with low concentrations of DEET to infants older than two months.
Parents concerned about the risk of applying DEET to children should consult their healthcare provider or the National Pesticide Information Center at 1-(800) 858-7378 or visit: http://npic.orst.edu .
There are certain precautions that should be followed when applying any repellent to children:
Apply it to your own hands and then rub them on your child. Avoid children's eyes and mouth, use the product sparingly around their ears, and don't apply to children's hands.
Keep repellents out of reach of children, and don't allow young children to apply insect repellent to themselves.
Do not apply repellent to skin under clothing. If repellent is applied to clothing, wash treated clothing before wearing it again.
Sandra Levy. Safety tips for lazy, hazy, crazy days of summer. Drug Topics Jul. 7, 2003;147:61.