The state Department of Health is testing mosquitoes and collecting reports of certain kinds of dead birds to monitor for West Nile virus, which is common in central and southcentral Washington.
Mosquitoes with West Nile were found in six counties in the state last year, including Benton, Franklin and Yakima.
The virus usually is active in spring and summer, when mosquitoes feed on infected birds, the health department said in a news release.
While most people bitten by infected mosquitoes don't have symptoms, some develop fever or headaches.
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"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 release said.
The health department recommends removing items that can attract and harbor mosquitoes, such as stagnant water in flower pots, old tires, buckets and gutters.
People also should keep windows and doors "bug tight" and try to protect against mosquito bites.
Staying inside at dawn and dusk -- the most active time for mosquitoes -- can help, along with wearing long sleeves and long pants when outside during those times and using an effective mosquito repellent.
To help keep tabs on West Nile, people are asked to report dead birds -- namely crows, ravens, jays, magpies and hawks -- using the health department's online reporting system.
For more information on West Nile or to link to the bird reporting system, go to www.tinyurl.com/westnilewa. The health department also has a West Nile information line at 1-866-78-VIRUS.