Many parts of the nation saw record numbers of West Nile virus cases this year, including the most human infections reported in Washington since 2009.

Of the four Washington residents with West Nile virus infections in 2012, two cases were acquired in-state — one in Benton County and one in Yakima County. The other two, who live in Pierce and Clark counties, were likely exposed while traveling out-of-state.

The Centers for Disease Control and Prevention reports more than 5,100 cases of West Nile virus in 48 states this year. In addition to the human cases in Washington, a horse in Benton County diagnosed with West Nile infection was euthanized and five mosquito samples from the south central part of the state tested positive for the virus. No birds tested positive this season.

In 2009, there were 38 human cases in our state — the most ever recorded here. Two Washington residents were reported with the infection in 2010; no human cases were reported in the state in 2011.

“Even though our numbers were small, this shows that West Nile virus is here and people should take it seriously” said Maryanne Guichard, assistant secretary for the state Department of Health. “Mosquito adults can survive the winter, so eliminating mosquito habitat now can help keep them away from your home come spring.”

Mosquito and dead bird monitoring and testing for West Nile virus has ended for another season. Even though cold weather has reduced the risk of mosquito bites, Guichard reminds residents to take a few off-season steps to reduce mosquito habitat. Dump water that collects around the home in flower pots, wheel barrows, garbage cans, and tires. Clean gutters and remove debris that may clog them. Prevent tarps from holding water when covering firewood, boats, or outdoor furniture. Even small amounts of water collected around the home can become mosquito habitat.

West Nile virus is spread by infected mosquitoes and can cause illness in people, birds, horses, and other animals. Most illness in people is mild with flu-like symptoms. In severe cases, people get very sick and may experience long-term disabilities. Local and state health agencies, mosquito control districts, and others work together to battle West Nile virus in Washington. While West Nile virus activity varies from year to year, mosquitoes carrying the virus remain a health threat.

West Nile virus is a reportable condition in our state, and details are available on the Department of Health website.

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