West Nile Virus

West Nile virus (WNV) is spread by infected mosquitoes and can be a serious health threat to people, birds and animals. Public Health - Seattle and King County leads the local response to WNV. For more information, view the WNV pages of these websites:

We can all reduce the risk of West Nile virus by reducing mosquito breeding and protecting ourselves from mosquito bites. Follow the techniques below.

Remove standing water:

  • Tip out barrels, buckets and wheelbarrows
  • Tip out containers such as toys, cans, and buckets
  • Empty children's wading pools when not in use
  • Change water in birdbaths and animal troughs at least once a week
  • Get rid of used tires
  • Clean garden ponds
  • Recycle old bottles, buckets and cans
  • Clean leaf-clogged gutters
  • Empty water from flower pot dishes
  • Dump water off of tarps and plastic sheeting
  • Repair leaky outdoor faucets
  • Cover rain barrels with mosquito screens
  • Help senior citizens and disabled neighbors or relatives with these activities. Consider holding a neighborhood clean-up day to get rid of junk that holds standing water.

Avoid mosquito bites:

  • Be aware of mosquito prime time biting hours: dawn and dusk
  • Wear long sleeve shirts, long pants and hats
  • Ensure window and door screens are in good repair and fit tightly
  • DEET (N,N-diethyl-meta-toluamide) or picaridin are known to be very effective mosquito repellents. Oil of lemon eucalyptus can also be effective but may not offer protection for as long as DEET or picaridin. Wearing special permethrin treated clothing can also help repel mosquitoes. It is recommended that DEET products not be used on infants under 2 months of age. More information about repellent use is located on the Centers for Disease Control and Prevention website.

 

Illness and Risk

Most people experience no symptoms from the bite of a mosquito infected with WNV. Twenty percent of people who become infected with WNV become ill with a mild-to-serious infection that can last for several weeks. Less than one percent (about 1 in every 150) of those who become infected develop the more serious neuroinvasive form of the disease. This can be fatal for a small number of people and sometimes leaves survivors with long-term effects such as weakness, cognitive impairment, or disability. People of all ages can become ill with West Nile Virus, but people over age 50 are at higher risk. The risk of getting a severe illness increases with age.