Washington Reports First WNV Human Case

Ruzanna Harutyunyan's picture

A Klickitat County man in his 50s is Washington’s first person in 2009 with a confirmed case of West Nile virus infection.

Testing at both the state’s Public Health Laboratories in Shoreline and at the federal Centers for Disease Control and Prevention (CDC) confirmed the diagnosis.

State health officials believe the man was infected in Washington. He didn’t travel outside the county during the exposure period, which was in early to mid-July. The man is recovering.

West Nile infection can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the spinal cord and brain). People over age 50 have the highest risk for serious illness. Younger people can also develop serious complications from the disease, which is fatal in rare cases.

Symptoms may include fever, headache, body aches, neck stiffness, stupor, disorientation, tremors, convulsions, muscle weakness, paralysis, and coma. People with lasting symptoms should contact a health care provider.


This case is a reminder of the importance of preventing mosquito bites to avoid West Nile virus infection and other mosquito-borne illnesses. West Nile virus is typically spread to people by mosquito bites. Mosquitoes become infected by feeding on birds that carry the virus.

People can avoid mosquito bites by following a few precautions: be sure that door and window screens are working; stay indoors around dawn and dusk when mosquitoes are most active; and use a mosquito repellent when mosquitoes are active. People involved in extended outdoor activities such as farming, hiking, sports events, or fishing and hunting should be careful to avoid insect bites. Always follow label instructions when using mosquito repellents.

It’s also important to reduce mosquito habitat around the home. Turning over old buckets or cans; emptying water from old tires; and frequently changing water in birdbaths, pet dishes, and water troughs helps eliminate the small puddles of water in which many mosquito larvae grow.

West Nile virus can also affect birds. People may report dead birds online to public health officials.

West Nile virus activity in Washington started earlier this year than in previous years. So far, environmental detections have been made in several counties, mostly in Eastern Washington. This includes 20 horses, eight birds, and 214 mosquito samples. Most mosquito testing this year has taken place on the eastern side of the state. Data is limited about West Nile virus circulation on the western side of the state, where so far the only detection of the season was a dead bird in Mason County.

Washington had three human West Nile infections in 2008, the state’s most active season to that point since monitoring began in 2001.