City Services

West Nile Virus


West Nile Virus is a mosquito-borne virus that can infect humans, birds, horses, and other animals.  There are many ways to protect yourself and your family from mosquitoes:

  •  Mosquitoes need water to breed and grow, so get rid of places where water can collect (cans, buckets, leaky faucets, barrels, used tires, clogged leaf gutters)
  • Any standing water on your property should be changed out once a week (birdbath, stock trough, flower pot dishes)
  • Garden ponds should be stocked with fish as they are natural predators of mosquitoes
  • Mosquitoes bite at dusk and dawn, so make sure to wear long sleeved shirts and pants in the early morning and evening
  • Use insect repellent when you will be outdoors.  The most effective repellents contain DEET, Picaridin, or oil of lemon eucalyptus
  • Install or repair screens on your windows to prevent mosquitoes from entering your home

For more information visit King County Public Health Services or the Washington State Department of Health

Get the Facts

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What are the symptoms of West Nile Virus?
Most people display no symptoms (80% infected), but in clinical illness cases (20%) people develop mild flu symptoms (fever, headache, nausea, rash) which may progress into ongoing fatigue and cognitive problems.

In less than 1% of those infected West Nile develops into a neuroinvasive disease (meningitis, encephalitis, paralysis, tremors) or immunosuppression.  Less than 0.1% of all cases are actually fatal
What should I do if I think I might have West Nile Virus?
Contact your health care provider for an examination.
How do I report a dead bird?

Please report all dead birds via the King County West Nile Virus page
When was West Nile virus discovered?
West Nile Virus was initially identified in the West Nile Province of Uganda in 1931.  Outbreaks traveled throughout Europe and Asia (Isreal 1951, France 1962, South Africa 1974, Romania 1996, Italy 1998, Russia 1999) before reaching the United States in 1999.  The virus was first detected in New York and quickly spread across the country with the highest cases seen in 2002-2003. Since then, the number of cases have dropped dramatically due to animal vaccinations, preventative measures, weather conditions, and public education.