West Nile virus strikes again.

Byline: Tim Christie The Register-Guard

CORRECTION (ran 9/14/04): Dr. Hank Anderson is a Eugene veterinarian. A front-page story in Saturday's Register-Guard about West Nile virus incorrectly reported where he lives.

It took a while, but West Nile virus has arrived in Oregon, infecting birds, horses and now its first human.

On Thursday, public health officials reported the state's first human case in Malheur County, the same day the virus made its first confirmed appearance in Lane County, in a dead crow found near Sheldon High School.

Lane County public health officials said Friday afternoon the virus had been confirmed in a second crow found in the River Road/Santa Clara area.

The first human case involved a teenage boy in Vale, in Eastern Oregon. Dr. Mel Kohn, the state epidemiologist, said Friday the boy was probably bitten by an infected mosquito in early August. He is back in school. Symptoms usually appear three to 15 days after infection.

Officials said Friday it's important for people to take precautions to protect themselves against mosquito bites, but also to keep the dangers from the disease in perspective.

The virus is new to Oregon - the second-to-last contiguous state to have a human case - but not to the rest of the country. In five years since West Nile virus was detected in the United States, about 14,000 cases and 580 deaths have been reported to public health authorities.

To put that in perspective, you're far more likely to get sick from eating an undercooked hamburger, tainted alfalfa sprouts or a funky oyster than from a mosquito bite.

An estimated 76 million Americans are sickened by food borne illness each year, of whom 325,000 wind up in the hospital and 5,000 end up in the morgue, according to the U.S. Centers for Disease Control and Prevention.

Every year, the flu sends 114,000 Americans to the hospital and kills 36,000, the CDC says.

Put another way: More Oregonians die from tobacco-related illness in two days - about 36 - than the number of Americans who have died from West Nile virus this summer - 30.

"On that scale, this is obviously a much smaller threat," Kohn said.

Four out of five people who become infected with West Nile virus will never know it. About 20 percent get sick and most of those will exhibit only mild, flu-like symptoms, public health officials said.

Of those who show symptoms, about one in 30 will develop life-threatening encephalitis, or swelling of the brain. People age 50 and older are at highest risk of severe illness.

This year's mosquito season will end with the first frost, likely sometime in mid-October. But now that West Nile virus is here, Kohn said, he wouldn't be surprised if several hundred cases were reported in Oregon next year.

``I would say that the second year after we've had an infection like this tends to be much worse,'' he said.

In other states, after an initial spike in cases in the second year after detection, the number of cases have declined as people and animals are infected and develop immunity, said Tamara Wilhite, Lane County's West Nile virus coordinator.

Now that the virus has been detected in a crow in Eugene, Wilhite said, county officials will no longer collect and test dead crows in the metropolitan area. However, they will continue to check for the virus in freshly dead crows and jays found in outlying areas, she said.

Lane County has no plans to launch a pesticide spraying program targeting mosquitos, said Rob Rockstroh, director of the county's Department of Health and Human Services. Given the size of the county and the amount of standing water, a spraying program is unlikely to be effective, he said.

"It's very expensive and it's probably not very practical," he added.

But county officials will continue to collect and test mosquitos for the virus, Wilhite said.

The mosquito testing program, begun in late August, is an affordable way to conduct surveillance for the virus, she said. Volunteers collect mosquitos in traps in the central part of the county, then bring them to Eugene, where part-time, temporary county employee John Parrott sorts and tests them for West Nile virus.

Parrott, a master gardener and self-described underemployed attorney with an active interest in insects, works in a cluttered storage room in the Lane County public health building. He examines the mosquitos under a microscope and sorts the three species known to carry the disease: culex tarsalis, culex pipiens and aedes vexans.

"They are beautiful creatures under a microscope," Parrott said. "They are elegant flying machines."

Once he's collected 30 to 50 mosquitos, he puts them in a grinder and makes a mosquito slurry, which he then tests for the virus. So far, he's not found any West Nile in the mosquitos he's tested, but he plans to keep looking.

West Nile virus afflicts not just humans, but also horses. About one in three horses that contract the virus will die, said Linda Lay, a veterinary technician at Del Oeste Equine Hospital in Eugene.

While no treatment for West Nile is available for humans, a vaccine for horses is available. Most horse owners have already had their animals vaccinated, Lay said, but some chose to wait until the virus arrived and others weren't aware of its threat to horses.

Dr. Hank Anderson, a Noti veterinarian, said, "Only the stragglers are worried now."

The Associated Press contributed to this report.

MYTHS AND FACTS ABOUT WEST NILE VIRUS

Four common myths about West Nile virus:

Myth No. 1: There's not much I can do about West Nile virus.

Fact: There's a lot individuals can do to reduce their chance of West Nile virus infection.

Reduce the number of mosquito bites you get when outdoors by using insect repellent with DEET on exposed skin and clothing. Prime mosquito-biting hours are usually dusk to dawn; pay special attention to protecting yourself during those hours, or don't go outdoors.

Reduce the number of mosquitoes around your home by eliminating sources of standing water. Get rid of containers that aren't being used, empty water from flower pots, change water in bird baths, and maintain clean gutters.

Make sure window and door screens are in good condition. Got an older neighbor or family member? See if they need help installing or repairing screens.

Myth No. 2: Kids are at the most danger of getting sick from West Nile virus.

Fact: People over 50 are at the highest risk of developing severe West Nile disease.

Relatively few children have been reported with severe West Nile virus disease. By contrast, most of the deaths due to West Nile virus during 2002 were among people more than 50 years old, and half those deaths were among people more than 77 years old.

Myth No. 3: It's only people who are already in poor health who have to worry about West Nile virus.

Fact: Healthy, active older adults who spend time working and exercising outdoors have been infected with West Nile virus.

Myth No. 4: Insect repellents containing DEET are not safe.

Fact: Repellents containing DEET are very safe, when used according to directions.

Because DEET is so widely used, a great deal of testing has been done. Different products have different strengths available. The longer the protection you need, the higher percentage of DEET needed. Repellents with DEET can be used for adults and children, except for children younger than 2.

- Centers for Disease Control and Prevention

Myth No. 5: As long as my area has a mosquito control program, I don't have to worry about using repellents.

Fact: Mosquito control activities don't eliminate every mosquito, so personal protection is still important.

CAPTION(S):

Brittany Petersen, 13, of Veneta holds her 11-year-old quarter horse, Sassy, while Dr. Hank Anderson administers the first of two vaccinations against the West Nile virus. On Thursday, public health officials reported the state's first human case in Malheur County. Two crows in the area also have been found with the virus, officials said.