Race is on for West Nile data

By Warren King
Seattle Times medical reporter

GREG GILBERT / THE SEATTLE TIMES Dave Oleyar, a UW graduate student, untangles a song sparrow from a net near Lake Sammamish used to capture birds being tested for West Nile virus.

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Suddenly the flight stops as the sparrow is snared in a soft, droopy net placed between two trees. Soon Dave Oleyar is gently untangling the chestnut and gray bird so it can do its part to protect us against West Nile virus.

West Nile, a potentially deadly infection first detected in the United States five years ago, is most associated with mosquitoes, whose bite can transmit the disease to humans. But it's birds that tell scientists where and when the unpredictable virus will crop up.

Battling West Nile Standing water: Reduce breeding places for mosquitoes by emptying anything outdoors that contains water, changing water in birdbaths and animal troughs weekly, cleaning leaf-clogged gutters, repairing leaky outdoor faucets and covering rain barrels with screens. Backyard ponds: Use environmentally friendly larvacides or larvae-eating goldfish and koi to control mosquitoes in ponds that are not connected to any natural body of water or constructed drainage system. Otherwise, a state permit is required for both. Avoid mosquitoes: Repair ripped window and door screens, wear long-sleeved shirts and pants when mosquitoes are out, and use mosquito repellent containing DEET. Report dead birds: Contact Public Health — Seattle & King County at 206-205-4394 or www.metrokc.gov/health/westnile/deadbird.htm. Snohomish Health District at 425-339-8720 Source: Public Health — Seattle & King County

"We'll get sort of a snapshot of the spread of the virus," says Oleyar, a University of Washington graduate student, shortly before taking a blood sample from a vein under the bird's wing. "Crows are hit hard and die, but songbirds act as reservoirs for the virus."

West Nile hasn't been detected in humans or animals in Washington state this year or last. But it was found in two birds — a crow and a raven — and in two horses in 2002. Health authorities say they need all the help they can get in figuring out when it might strike here again.

Experts, for the most part, are puzzled why Washington is one of only four states — with Oregon, Alaska and Hawaii — that haven't had human cases originate within their borders. Or why no virus was detected even in animals in Washington last year.

"If I could answer that question, I'd have a Nobel Prize," says Dr. Jo Hofmann, state epidemiologist for communicable diseases. "No one understands why it is creeping across the country in such a strange way."

Colorado hardest hit

West Nile first surfaced in the United States in 1999, infecting 62 people and killing seven, mostly in the New York area. Last year, there were 9,682 cases and 264 deaths nationwide. Nine cases have been reported this year, none of them fatal.

About one in five people infected get sick, and only one in 150 people with the virus develop potentially fatal neurological problems. Symptoms typically include fever, muscle aches, fatigue, headache, rash and joint pain.

Information Public Health — Seattle & King County: 206-205-3883 or www.metrokc.gov/health/westnile

Scientists believe migratory birds, including many songbirds, are infected when they winter in Central America with other migratory birds that already carry the virus.

But the spread of the disease across the United States has been surprising.

After moving through the East and Midwest, it stopped at the Continental Divide, then popped up in erratic ways in Western states. Colorado led the nation last year with 2,947 cases and 63 deaths. Utah had one case; New Mexico, 209; Arizona, 13; Wyoming, 375.

Thirteen people out of 110 suspected cases tested positive with the disease in Washington state last year, but all acquired the virus while traveling in other states, health officials say. Officials tested 104 horses that seemed to have symptoms, but none tested positive for the virus. About one-third of infected horses die of the disease.

"It's just unpredictable," says Tom Gibbs, the state Department of Health's West Nile project coordinator. "I wouldn't be surprised if we detect the virus in the state this year. But I'm surprised we didn't detect it last year."

Some experts suspect last summer's dry weather played a role in keeping the virus away.

	GREG GILBERT / THE SEATTLE TIMES Dave Oleyar, a UW doctoral candidate, records data near Lake Sammamish while holding a black-headed grosbeak. The bird was soon released.

Standing, stagnant water was not as plentiful, and the larvae of virus-carrying mosquitoes had fewer places to grow, they say.

Still, plenty of larvae were found by government workers and researchers testing areas throughout the county. And nine different species of mosquitoes that can carry the virus — and bite both birds and humans — were found in Washington state.

Research under way

Oleyar and Jack DeLap, doctoral candidates in the UW's Department of Forest Resources, are looking for the virus in songbirds at 31 sites, mostly in King County.

Along with other UW graduate students, they are examining the effect of urbanization on bird populations. They take blood samples for West Nile testing to assist health authorities and as part of an extensive UW research project on the ecology of the virus.

On a recent morning, Oleyar and DeLap weaved through the wet woods, checking their nearly invisible bird nets. Decoys were placed at some, and a few had hidden speakers emitting the songs and calls of a variety of birds.

By 10 a.m., they had trapped two song sparrows, two black-headed grosbeaks, a spotted towhee and a chestnut-backed chickadee. Each bird is weighed, its colorful wings measured, feathers analyzed for age, and tiny leg bands attached for future identification.

Then DeLap holds the bird while Oleyar pricks a vein under the left wing, draws the bright red blood into a glass tube and stores it in a padded box for shipment to a New York laboratory. A piece of cotton is held on the wound until the bleeding stops and the bird can be released.

John Marzluff, a UW professor of forest resources who oversees the research and is an expert on crows, watches in wonder at the spread of the virus across the country.

In his cluttered office in the UW's Anderson Hall, he ticks off some of the Northwest birds that don't survive West Nile: corvids — including crows, ravens, magpies and jays; raptors — including red-tailed hawks, great horned owls, spotted owls, northern groshawks, Cooper's hawks and screech owls; and black-capped and chestnut-backed chickadees.

No one knows why some birds can live with the virus and others don't. House finches and house sparrows, American robins and ring-billed seagulls, all found in Washington, are known to survive, Marzluff says. Thus, they are called "competent hosts" for the virus.

Overall, more than 140 bird species in North America can harbor the virus and transmit it to mosquitoes.

"It's affecting some birds, but not all, and for some it is very virulent. ... It's anybody's guess as to what will happen where," Marzluff says.

	Dave Oleyar holds a small vial of blood taken from a black-headed grosbeak. The sample will be sent to a lab in New York and tested for West Nile virus.

Crows important sentinels

Marzluff and his colleagues are looking further into the role of birds in the spread of West Nile. Along with health officials, they monitor reports of dead crows to Public Health — Seattle & King County, looking for patterns that may warn of the virus and establishing a baseline map for watching its progress. Crows die about five days after infection and have been important sentinels for the disease in other cities.

The researchers also plan to analyze what effect crows' nesting patterns have on spread of the virus. Because crows prey on songbird eggs and young songbirds, they will monitor whether crow deaths result in more songbirds — many of which can carry the virus throughout their lives. And they will analyze crows' blood, looking for signs of resistance to the virus.

King and Snohomish counties and other governments statewide have programs asking residents to notify officials of dead birds, especially crows. Many health departments, including Public Health — Seattle & King County and Snohomish Health District, will pick up some animals if they appear newly dead. The birds are then put on ice and shipped to the National Wildlife Health Center in Madison, Wis., for testing.

Last year, Public Health received 2,700 reports of dead birds, and 155 animals were tested, says Dr. Sharon Hopkins, head of the department's West Nile prevention efforts. Statewide, more than 900 dead birds were tested.

"We know this is coming," Marzluff says of the virus. "People should take precautions. It's most important to look for dead crows. If we do, maybe we can stay ahead of the severe (disease) that can result."

Warren King: 206-464-2247 or wking@seattletimes.com

Information

Public Health — Seattle & King County: 206-205-3883 or www.metrokc.gov/health/westnile

Copyright © 2004 The Seattle Times Company

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