West Nile Virus

About West Nile Virus (WNV)

West Nile virus is a mosquito-carried virus that can cause serious illness. West Nile virus is spread to humans and animals through the bite of an infected mosquito. Mosquitoes spread the virus when they feed on an infected bird, and then bite people, animals, or other birds.


Most people who are infected with WNV will not become ill. Two to fourteen days after being bitten by an infected mosquito, some people may develop flu-like symptoms such as fever, headache, and body aches. Occasionally, they may have swollen glands or a rash. These symptoms can last for a few days or up to several weeks.

In rare cases, infection can result in a severe and sometimes fatal illness. Serious infection is marked by high fever, severe headache, stff neck, muscle weakness, disorientation, and convulsions. Some symptoms may persist for years.

If you begin to experience serious symptoms of infection 2-14 days after a mosquito bite, see your doctor.

With serious West Nile illness, intensive medical care may be required, such as hospitalization, intravenous fluids, and prevention of secondary infections such as pneumonia.

There is currently no vaccine available for humans

Anyone, at any age, can contract WNV infection. The risk of severe infection is higher among people who are 60 or older.

WNV is not spread by person-to-person contact

(for example, you won’t get it by touching or kissing an infected person). A very small number of people have been infected with WNV through blood transfusions and organ transplants, and through transmission from mother to baby during pregnancy or breastfeeding.

There is no evidence that people can get West Nile virus directly from infected birds, dead or alive. However, people should avoid touching any dead bird or animal with their bare hands.

How to Prevent WNV

  • Twice a week, drain standing water on your property and routinely empty anything that holds water, including buckets, wading pools, pet bowls, tire swings, bird baths, and toys.

  • Keep door and window screens “bug tight.” Repair or replace them as needed.

  • Wear shoes, socks, long pants and long sleeve shirts when outside, especially at dawn and dusk when mosquitoes are most active.

  • Use insect repellents according to directions.

Safe use of insect repellents

Repellents containing the following ingredients are effectve against mosquitoes:

  • DEET
  • Picaridin (also known as KBR 3023)
  • Oil of Lemon Eucalyptus (OLE) or para-menthane-dial (PMD)
  • IR3535
  • Permethrin
  • 2-Undecanone

Permethrin is recommended for use on clothing, shoes, bed nets, and camping gear. Permethrin treated clothing repels and kills ticks and mosquitoes and retains this effect after repeated laundering. Follow directions carefully.

Repellents used on children should contain no more than 30% DEET. Insect repellents are not recommended for children younger than two months.

  • Spray your own hands and then rub the product on child’s exposed skin, avoiding eyes and mouth. Children should not apply repellent themselves.
  • If a child still puts their hands in their mouth, do not apply repellent to hands.
  • Consider using mosquito netting over infant carriers, strollers or playpens.
  • Always keep repellent out of reach of children.

If you suspect you or your child is having a reaction to an insect repellent, discontinue use, wash treated skin thoroughly and call the Washington Poison Center 800.222.1222. If you go to a doctor, take the repellent with you.

Reporting Dead Birds for WNV

Birds and horses typically become infected with WNV before humans, so dead corvid birds and sick horses can be an early indicator that there is WNV activity in an area. Previously, to conduct WNV surveillance, Washington State Department of Health’s (DOH) Zoonotic Disease Program operated an online dead bird reporting system. The system was intended to help with detection of WNV, and provide a means for the public to help with the surveillance. In addition to providing adequate evidence of where WNV was endemic, DOH determined that surveillance of mosquitoes is a better system for early detection of WNV in the environment. This meant discontinuation of the dead bird system to better focus resources on what benefits public health.

What to do when you find dead birds

To report wild bird die-offs contact the local office of Washington Department of Fish and Wildlife (WDFW) at 509-892-1001. To report domestic flock die-offs, contact the local office of Washington State Department of Agriculture (WSDA) at 509-533-2690.

Please DO NOT bring birds to any health district office unless you are requested to do so!

Always use precautions when handling and disposing of any dead bird or animal

  • Wear gloves or use a shovel to put the bird into a plastic bag. Put into another plastic bag and close tightly.

  • Place the dead bird into garbage can.

  • Wash hands thoroughly with soap and water.

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