West Nile virus jumps the Cascades, found in Pierce County

A routine sampling of wetlands near the Port of Tacoma tested positive for West Nile virus, and health officials say people should assume an infection is possible in Pierce County.

The sampling, taken by the Department of Health at the Gog-le-hi-te Wetlands on Aug. 14, is the first detection of the virus in mosquitoes west of the Cascades.

Mosquito season usually ends in mid-September.

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DOH said it shared test results with the Tacoma-Pierce County Health Department late last week.

“People should assume West Nile Virus infection is possible in Pierce County and take steps to prevent breeding mosquitoes and avoid mosquito bites,” said Nigel Turner, director of the Communicable Disease division. “Most importantly, know when to get care if you have been bitten,” he said.

It only takes one bite to acquire the virus from an infected mosquito, and West Nile virus can pose a health threat to anyone exposed. But less than 1 percent of people infected with the virus will develop severe illness, health officials say.  Those at a higher risk of severe disease include people age 60 or older or those with already compromised immune systems or existing medical conditions.

Symptoms of West Nile virus

Tacoma-Pierce County Health Department says symptoms usually appear two to 14 days after being bitten by an infected mosquito and include headache, fever, muscle and joint aches, swollen lymph nodes and a rash.  Those with more severe symptoms, such as severe headache, stiff neck or confusion, should see a doctor.

No cases of West Nile virus have been diagnosed in Pierce County among people, birds or horses, and activity usually appears in early to mid-August.

Health officials says people should take measures to control mosquitos to prevent bites, and if you find a dead bird, do not pick it up with bare hands, as some birds may die from the virus.

Find information about dead birds, West Nile virus prevention and mosquito repellents at www.tpchd.org/westnile.

West Nile virus was seen in birds in Pierce County in 2002, 2008 and 2009, and two people tested positive for the virus in 2006.

Department of Health maps and statistics show where the virus is throughout Washington state. Currently, no cases have been reported in humans in Washington this year.

Last year, nearly every state and the District of Columbia reported West Nile virus infections in people, birds or mosquitoes.

DOH says 231 people have had the virus and 8 have died from it nationwide.

No vaccine is available for humans, but there is one available for horses.