SEATTLE -- Madrona K-8 in Seattle has been closed after one of its students was identified as among six probable swine flu cases in Washington.

In addition, a pediatrician at Everett Clinic has been identified as one of the six cases. The clinic is contacting the parents of all patients she saw on Monday.

The state Health Department cautioned that more probable cases of flu might be found in Washington as additional tests are conducted for the disease.

Seattle Public Schools and Public Health-Seattle & King County said Thursday that Madrona Elementary in the city's Mount Baker neighborhood would be closed through Wednesday.

"We thought this was an important precaution" to close the school, Dr. Jeff Duchin of the health agency told a Thursday morning news conference outside the school. "We want to prepare for something that is more serious."

An 11-year-old student at the K-8 school had a cough and fever Monday and his mother kept him home, school officials said. He was later hospitalized and is recovering.

Duchin said no other cases had been found at Madrona and none of the six probable case in the state are connected.

School district spokesman David Tucker said officials had planned to allow the school to remain open, but health investigators determined the infected boy may have been ill last Friday at the school.

To avoid possibly spreading infection, the district asked Madrona students and families to not gather outside the school the week it is closed. If anyone does become sick, they should stay home for seven days after the illness starts or for a full day after it is over, whichever is longer, and call a health care provider if symptoms are severe, the district said.

Testing under way

State Health Department spokesman Tim Church said Thursday that it and the federal Centers for Disease Control and Prevention are continuing to test Washington samples for swine flu. The state is waiting for confirmation on the six suspected cases from the CDC.

By next week, Church said a state laboratory at Shoreline, north of Seattle, will be equipped to confirm swine flu cases.

Three of the suspected cases, including the Seattle boy, are in King County, two are in Snohomish County, just north of Seattle, and one is in Spokane County in Eastern Washington.

Dr. David Fleming, director and health officer for Public Health-Seattle & King County, said he expects the region will see more infections of the swine flu H1N1 virus, which has been confirmed or suspected in dozens of patients in at least a dozen other states and several foreign countries.

The other King County cases are a 27-year-old Seattle man, and a 33-year-old Seattle woman who works as a pediatrician at the Everett Clinic, and whose husband and two children have also shown symptoms. They were not hospitalized and are improving, the Health Department said.

Two Cases In Snohomish County

Two residents of Snohomish County are also probable to have swine flu. One case involves a 34-year-old Lynnwood woman, and the second is a 3-year-old Snohomish boy, said Dr. Gary Goldbaum with the Snohomish County Health District.

The boy's age was initially reported as 6-years-old, but it turns out that was his brother. He too showed symptoms but has originally tested negative for the flu. Goldbaum says the boy will be retested, but both are recovering.

The family recently visited Mexico and Goldbaum says other family members are not reporting symptoms.

Goldbaum says the source of the Lynnwood woman's illness is a mystery as she has not traveled or been in contact with anyone who recently traveled. But he added he expects the virus to keep spreading.

"I expect the state is going to announce more cases every day from this point on for at least the next several days to weeks," he said.

The Spokane case involves a man in his 40s who recently traveled to California, the Spokesman-Review reported.

Spokane Regional Health District spokesman Pat Humphreys said Thursday that authorities have not made contact with the man, and don't know where he works or if he has children in school.

At this time, all schools and other public facilities in Spokane remain open. No decision has been made on whether to cancel this weekend's Bloomsday road race, which typically draws more than 40,000 people from all over the world.

So far, cases have been mild

Dr. Goldbaum said the concern over swine flu was great because the initial cases that developed in Mexico had a very high fatality rate.

But so far, most cases in the United States have been mild -- on par with the common variety influenza.

"What we're witnessing in this county appears to be a relatively milder form of influenza -- milder than what appeared in Mexico," he said. "The fact that it's sensitive to these anti-virals is great news, unlike the avian influenza where we're very concerned about (drug) resistance. This means we have treatment available. It appears at least in this country, most cases won't even require treatment and they will recover on their own."

But he stresses officials are keeping a high alert.

"It's just we don't know for sure and we don't understand why the cases in Mexico look different. And until we can be very clear on what happened in Mexico, we're treating this as potentially a much more severe disease than it may prove to be," he said.

Ways to keep informed

Snohomish County Executive Aaron Reardon says the county will be posting updates and answering questions via Facebook and Twitter in addition to updating their own web site at www.snohd.org.

On Facebook, search for "Snohomish County Health District". On Twitter, they are user SnoCo_DEM.

And starting 9 a.m. on May 1, they will have a call center for Snohomish County Residents to ask questions: (425) 388-5060.

Simple precautions

State Secretary of Health Mary Selecky urged people to follow basic precautions to prevent spread of the disease.

"We need the people of our state to help prevent the spread of germs by covering their coughs and staying home if they're sick," she said. Health experts also recommend frequent hand washing.

The state Health Department said in a news release that there is no vaccine to prevent swine flu, but the state expects to receive a precautionary supply of antiviral medication - enough to treat about 230,000 people - in the next several days from the federal government.

The outbreak has hit about a dozen states amid confirmation of the first U.S. death - a Mexican toddler who visited Texas with his family - and the confinement of dozens of Marines after one came down with the disease in California.

The Washington cases were discovered from among about 70 samples that have been sent so far to the state testing lab in Shoreline. Testing continues on dozens of those samples sent in since last weekend by hospitals, clinics and doctors.

Symptoms of the swine flu are typical of other flu strains, including fever, coughing, joint aches, headache, and in some cases vomiting and diarrhea.

Health officials say the disease, despite its name, is spread from human to human - not from pigs to humans - and that it is not spread by eating properly cooked pork products.

Seattle Mayor Greg Nickels said the city would activate its Emergency Operations Center at its first level to coordinate procedures and communications that might be needed in response to the flu cases.

"I think president Obama said it best when he said this is something for us to be concerned about, but not to be alarmed about," said Seattle Mayor Greg Nickels. "The main message is we can do a lot to prevent the spread of this by taking very simple, very common-sense measures."

Thanks to previous federal grants for pandemic preparedness, state health officials have TV public service advertisements ready, they've written up plans and practiced exercises on how to receive and distribute medication to combat the flu, and there's flu information available online, Church said.

Local health officials meet daily by phone with the state Health Department and everyone is working on getting information out to the public, Church said.

"We have a plan in place. We've practiced it. Everybody knows their roles," he said. "Four to five years ago, we wouldn't have had that in place."

Church said the overall flu season, which typically peaks in February, is tailing off. He said there have not been an abnormal number of flu cases for this time of year in the state.

The department estimates the flu situation by checking with a few schools and nursing homes.

The University of Washington has a small number of students in Mexico, about eight or nine, but the university is not advising them to come home, UW spokesman Bob Roseth said.