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West Nile Virus RisKey
A Little Bite of Prevention
 
It is believed that West Nile Virus (WNV) is a seasonal epidemic in North America that flares up in the summer and continues into the fall. WNV circulates between birds and mosquitoes, with humans as the dead-end hosts. This RisKey outlines some simple precautions that can be performed to help with your potential exposure to mosquito bites.
 
For information on how to report a dead bird refer to the Oregon Department of Human Services Web site. Please refer to the section on disease reporting. The second paragraph directs you to a PDF document which outlines the contact information. If you need to pick up a dead bird avoid bare-handed contact. Use gloves, a shovel or an inverted plastic bag to place the bird carcass inside two plastic bags or two garbage bags. Keep the dead bird carcass cool, but do not place it in your refrigerator.
 
It is currently believed that WNV is a seasonal epidemic in North America that flares up in the summer and continues into the fall. This is being monitored by appropriate government agencies.  
 
In the meantime remember the following prevention methods:
  • Water Source Elimination
  • Apply Insect Repellent Containing DEET
  • Clothing Can Help Reduce Mosquito Bites
  • Be Aware of Peak Mosquito Hours 
  • Home Care

Water Source Elimination
 
One of the best methods of providing long-term mosquito control is eliminating water sources which promote mosquito reproduction.  Some ideas for water source reduction are as follows, keep in mind that there are others:
  • Clean your rain gutters.  Keeping your rain gutters clear will eliminate any standing water.
  • Properly dispose of any tires, bottles, etc., which will collect water. 
  • At least once or twice a week remove water from:
    • Bird baths
    • Empty flower pots
    • Swimming pool covers
    • Buckets
    • Barrels/Cans
  • Drain and clean water sources for animal use, such as horses, cows, dogs or cats weekly.
  • Check for containers or trash in places that may be hard to see, such as in bushes or under your house.
 

Apply Insect Repellent
 
The Center for Disease Control & Prevention (CDC) states that DEET is the most effective and best-studied insect repellent available.  DEET should be applied when you venture outdoors, especially from dusk to dawn.  Review the following recommendations about using DEET:
  • Read all the directions on the product label before applying the repellent. 
  • Use enough repellent to cover exposed skin or clothing.  Don’t apply repellent to skin that is under clothing.
  • 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 directly to your face.  Spray your hands and then rub them carefully over your face, avoiding eyes and mouth.
  • DEET should not be used in a product that combines the repellent with a sunscreen.  Sunscreens often are applied repeatedly because they can be washed off.  DEET is not water-soluble and can last up to 8 hours.  Repeated application may increase potential toxic effects of DEET.
  • If repellent is applied to clothing, wash treated clothing before wearing it again.
  • Do not use DEET near any food.
Application for children:
  • Make sure that you refer to the above listed bullets for children in addition to those listed below.
  • The American Academy of Pediatrics recommends insect repellents containing DEET.  Repellents containing DEET with a concentration of 10% appear to be as safe as repellents with a concentration of 30% when used according to the directions on the product labels.  The efficacy of DEET maximizes at a concentration of 30%, the maximum concentration currently recommended for infants and children. The major difference in the efficacy of products relates to their duration of action. Products with concentrations around 10% are effective for periods of approximately two hours. A prudent approach would be to select the lowest concentration effective for the amount of time spent outdoors. It is generally agreed that DEET should not be applied more than once a day.  Parents concerned about applying DEET to children should contact their healthcare provider.
  • DEET is not recommended for use on children under two months of age.
  • Apply 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.  Children have a tendency to put their hands in their mouth frequently.
  • Keep repellents out of reach of children.   This is considered a toxic substance and can be a danger to children.
  • Place mosquito netting over infant carriers when you are outdoors with infants.

Clothing can Help
 
When possible, wear long-sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or DEET will give extra protection. Don´t apply repellents containing permethrin directly to skin. Permethrin insect repellent is a clothing treatment that both kills and repels mosquitoes, ticks and many other insects. Permethrin insect repellent clothing treatment binds to the fibers of fabric, similar to colorants, and remains effective for up to two weeks or longer, through regular washings. Permethrin insect repellent may be used on clothing, sleeping bags, tents, or stroller nettings. Do not spray repellent containing DEET on the skin under your clothing.  Make sure that you wash clothing that has been sprayed with DEET before wearing it again.
 

Peak Mosquito Hours
 
The hours from dusk to dawn are peak mosquito biting times for many species of mosquitoes. Take extra care to use repellent and protective clothing during evening and early morning -- or consider avoiding outdoor activities during these times.
 

Home Care
 
During the summer it is enjoyable to open up windows on nice days.  Make sure you have screens on your windows and doors. Inspect the screens to ensure they will not allow a mosquito to venture indoors.
 

Conclusion
 
80% of people infected with WNV will not show any symptoms at all.  Of the 20% who do show symptoms they may have a fever, headache, body aches, nausea, vomiting and sometimes swollen lymph glands or a skin rash.  These symptoms generally last a few days.  Of the 20% who do exhibit symptoms the chance of severe symptoms only occurs in about one in 150 people.  The symptoms require medical attention and can last for several weeks.
 

Resources
 
Here are a few website addresses to view for additional information:
Have a great summer!
 
History: New 5/04. Revised 8/04 and 3/05.