West Nile virus hasn't hit in county

Mosquito-borne disease has been rampant in other parts of country

By Marissa Harshman, Columbian health reporter



The country's biggest West Nile virus outbreak has yet to spread to people in Washington.

And the Clark County Mosquito Control District hopes to keep it that way.


The risk of contracting West Nile virus is low, but anyone can become infected, according to health officials.

Most people who are infected with West Nile virus will not get sick. About one in five people infected will have mild symptoms such as fever, headache, and body aches. About one in 150 people infected will have more severe symptoms such as headache, high fever, neck stiffness, stupor, disorientation, tremors, convulsions, muscle weakness, paralysis, and a coma.

Earlier in the summer, county crews focused on eliminating pesky floodwater mosquitoes, which don't carry the virus. But now that we've transitioned into the warmer summer months, crews are shifting their attention to the species that carries West Nile virus, said John Jacobson, a crew supervisor for the district.

Mosquito control

To report possible mosquito breeding sites to the Clark County Mosquito Control District, call 360-397-8430 or visit its website.

County crews are targeting breeding areas across the county — places with standing water, such as catch basins — to try to kill the

mosquito larvae before they have a chance to become adult, flying mosquitoes, Jacobson said.

"We've been very, very aggressive in identifying the breeding sites and treating them when they're larvae," he said.

Crews are finding the mosquitoes, just not in as large of populations as in other places in the country, Jacobson said.

West Nile virus is almost always transmitted to people who are bitten by an infected mosquito. Mosquitoes get the disease from feeding on infected birds.

So far this year, the Centers for Disease Control and Prevention have recorded 1,590 human cases of West Nile virus — the most reported through August since the virus was first detected in the U.S. in 1999. Sixty-five people have died from the disease this year.

A majority of those cases — 733 of the 1,590 — are in Texas, which has had 30 deaths. Mississippi and South Dakota are reporting 98 human cases each, for a total of three deaths. Louisiana reports 73 cases and six deaths, according to the CDC.

This week, Oregon reported its first two cases in humans — one in Coos County on the Oregon Coast, the other in Malheur County in Eastern Oregon. The state has also detected 58 cases in mosquito pools, which are groups of mosquitoes taken from a location and tested.

In Washington, health officials have not reported any cases in humans. The last time Washington state had a West Nile case in a human was in 2010, according to the Washington State Department of Health.

A horse in Yakima County, however, did contract the disease recently and was subsequently euthanized, according to the Washington State Department of Agriculture. Washington health officials have also reported five cases of West Nile virus found in mosquito pools, none of which were in Clark County.

The Clark County Mosquito Control District continues to monitor the local population by trapping adult, flying mosquitoes. The trapping allows crews to monitor the number of adult mosquitoes and test for West Nile virus when the species that carries the virus is discovered.

"We're finding our mosquito population is lower than it's been in past years," Jacobson said.

In addition to the trapping, crews will continue spraying catch basins until Oct. 1, when the county mosquito control board will determine whether to extend treatment, he said.

The public can also help curb the mosquito population growth by removing sources of standing water, such as buckets and tires, and changing the water in bird baths and animal troughs twice a week, Jacobson said.

People can protect themselves from mosquito bites by avoiding being outside at dawn and dusk when mosquitoes are most active, wearing long-sleeved shirts and pants and using proven mosquito repellent, he said.

Marissa Harshman: 360-735-4546; http://twitter.com/col_health;http://facebook.com/reporterharshman;marissa.harshman@columbian.com.