For immediate release: November 20, 2003 (03-186)

Contacts:
Tim Church, Communications Office 360-236-4077
Donn Moyer, Communications Office 360-236-4076

Colder weather signals end of 2003 dead bird surveillance for West Nile virus
Still no human cases of WNV illness acquired in Washington state

OLYMPIA ¾ The cold weather season has arrived, reducing mosquito activity and bringing with it a change in the Washington State Department of Health West Nile virus (WNV) surveillance project. The agency is suspending lab tests of dead birds where mosquito activity has ended. The project will resume testing of some dead birds in the spring of 2004 after mosquito activity increases.

"Even though none of the dead birds tested this year in our state were infected with West Nile virus, we have a history of mosquito-borne viruses and illness here so this work is very important," said Maryanne Guichard, director of Environmental Health and Safety. "Dead bird surveillance provided the first indication that West Nile virus had arrived in our state last year. Surveillance helps us quickly inform the public and respond early to reduce cases of illness."

In 2003 there were no reported human WNV infections acquired in Washington state. More than 100 people were evaluated for suspected WNV infection by local and state health departments, and had specimens sent to the state Public Health Laboratories for WNV testing. To detect virus activity, nearly 900 dead birds, 67 horses, and 435 samples from sentinel chicken flocks in Washington were tested; however, none of them were infected. Washington and Oregon were among only five states in the U.S. that have not detected any WNV activity in 2003.

In 2002 two dead birds were confirmed with WNV and two cases of WNV infections were reported in horses in Washington.

According to Guichard, people have some control over personal exposure to mosquitoes and the diseases they carry. An important precaution is eliminating potential mosquito breeding habitat around the home, such as containers that may catch and hold water. Emptying or removing such containers is essential even in winter, because mosquito larvae may survive the cold winter months and hatch in the spring. Guichard adds personal protective measures include wearing long sleeves and full-length pants in the outdoors when mosquitoes are active and using bug repellants that include DEET.

West Nile virus is spread to birds, horses and humans by infected mosquitoes, but most people that are bitten by an infected mosquito do not show signs of illness. Rare human cases have been transmitted through blood transfusion, organ transplantation, and breast-feeding. The most severe illnesses include swelling of the brain and occasionally death.

Between January 1, 2003 and November 19, 2003, the Centers for Disease Control and Prevention (CDC) (http://www.cdc.gov/ncidod/dvbid/westnile/surv&controlCaseCount03.htm) reported 8,470 WNV illnesses nationally with 189 deaths. There have been no reported human cases of West Nile virus illness acquired in Washington; however in 2003, four Washington residents contracted WNV infections after exposure to mosquitoes in other states.

More information is available on the Department of Health West Nile virus Web site (http://www.doh.wa.gov/ehp/ts/Zoo/WNV/WNV.html ).

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