West Nile virus Detected in Washington State June 22, 2010

July 6, 2010, 2:14 p.m.

West Nile virus in Grant County mosquitoes are season’s first in state
Virus presence is a reminder to protect against disease by avoiding mosquito bites


"Last year was the busiest so far in our state for West Nile virus," said Gregg Grunenfelder, environmental health division assistant secretary for the state Department of Health. "We had more human cases, positive mosquito samples, horse cases, and dead birds than ever last year. Dozens of people were infected and one died in Washington in 2009, so it’s clear that West Nile virus can be very serious. Avoiding mosquito bites is the key to preventing infection."

Grant County Mosquito Control District #1 has been monitoring for the virus since early spring and spraying in areas with high mosquito populations. The district plans to continue spraying for mosquitoes this week. Call 509-765-7731 for information about the spraying schedule.

Last year in the state, West Nile virus was detected in 22 dead birds, one dog, 346 mosquito samples, and 72 horses. Half of the infected horses died or were euthanized. Contact a veterinarian to learn about horse vaccines; it’s not too late to vaccinate horses against West Nile. There were also 38 human cases reported including one death in 2009, with all exposures in Eastern Washington or out of state.

The best strategy against diseases transmitted by mosquitoes is to use bug repellant and wear long pants and sleeves outdoors when mosquitoes are active. Stop mosquitoes in their tracks by getting rid of standing water that collects around your home. Dump water in wading pools, tires, or old flower pots. Change water in pet dishes and bird baths at least once a week; twice a week is preferred. Keep screens in working order to keep mosquitoes from getting inside the home.

For some people, West Nile infection can be very serious, and even fatal. Some people may develop meningitis or encephalitis; some neurological effects may be permanent. The majority of people bitten by a mosquito carrying the virus won’t become ill, yet some may have mild symptoms including headache and fever that go away without treatment. People over 50 and those with weak immune systems are at higher risk for serious illness.


¾ Mosquito samples collected in Grant County that tested positive for West Nile virus are the first signal of the presence of the virus in Washington in 2010. Environmental monitoring resumed around the state this spring and mosquito season is well underway.

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