West Nile Virus Tracking Underway Across Washington State

OLYMPIA - The Department of Health is again monitoring for West Nile virus through mosquito testing and collecting reports of certain types of dead birds. The virus is now well-established in some areas of the state. West Nile virus typically becomes active in the spring and summer during mosquito season when the insects feed on infected birds.

Mosquitoes that tested positive for the virus were found in six counties last year (Benton, Franklin, Grant, Skagit, Yakima, and Spokane). The virus has been common in Central and South Central Washington during the past several years. Studies show the weather, irrigation and vegetation in those areas, especially in and around orchards, are a favorable environment for the types of mosquitoes and birds that carry the virus.

While there haven’t been many cases of Washington residents infected with West Nile virus over the last few years, the virus can cause a serious illness for some people. Most people bitten by an infected mosquito won’t have symptoms. Some may develop mild symptoms, such as fever or headaches that go away without treatment. People with weakened immune systems and those over 50 are more likely to develop serious illnesses, which can include meningitis or encephalitis. Some neurological effects can be permanent.

The virus is spread by the bite of infected mosquitoes. Avoiding mosquito bites and removing items that can become mosquito habitat are the best defenses against West Nile virus. Mosquitoes only need a small amount of water for breeding. Emptying stagnant water in flower pots, old tires, buckets, gutters, and other water-collecting items can make it harder for mosquito larvae to grow into biting adults.
Staying indoors during dawn and dusk when mosquitoes are most active can also help you avoid mosquito bites. Inspect windows and doors to make sure they’re “bug tight.” Wearing long sleeves and long pants outdoors during these times is also good protection, along with using an effective mosquito repellent.

Birds in the crow family are also susceptible to West Nile virus and can provide an early warning of virus activity. The Department of Health asks people to report dead birds using its online dead bird reporting system. Crows, ravens, jays, magpies, and hawks are particularly important to report because they often die from West Nile virus infection. The information helps state and local health agencies identify unusual increases or clusters of bird deaths. Knowing these areas helps with prevention and control strategies.

More information is available on the agency’s West Nile virus information line, 1-866-78-VIRUS (1-866-788-4787) and the Department of Health website (

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