SAN DIEGO -- A private school in Mira Mesa where one student tested positive for swine flu was closed Monday after a half-dozen teachers became ill, San Diego County health officials said.

Christ the Cornerstone Academy was closed as a precautionary measure while tests are conducted to see if the six teachers suspected of having swine flu actually contracted the disease, said Dr. Wilma Wooten, San Diego County's public health officer.

Additionally, another case of swine flu was confirmed in San Diego County Monday, bringing the total to five, and state health officials said two more people in the county are likely infected with the virus as well.

The most recent confirmed case of swine flu in the county involved a 20-year-old man, Wooten said, adding that all of those who were infected have recovered and did not require hospitalization.

Two more people in the county are likely infected with the virus, as well, but confirmation is still pending from the U.S. Centers for Disease Control and Prevention, Wooten said.

The two are relatives of a 7-year-old with a confirmed case of swine flu.

According to Wooten, new guidelines from the CDC mandate that schools close for a period of seven days after only a single case of swine flu has been confirmed.

Wooten said if residents are sick, they should stay home from work or school.

Enough doses of anti-viral medications for 50,000 people have been ordered for the San Diego region from a strategic national stockpile, she said. "This is changing very rapidly, so tomorrow we may very well have new cases," Wooten said.

"We know that the virus is spreading from person to person," she said.

"What we are now in is what's called a mitigation phase. We are trying to slow, decrease the spread of the disease. "We know that this swine flu virus is throughout our community," Wooten added. "It's in various states throughout the U.S. It's in various countries throughout the world."

As of Monday afternoon, there were 11 confirmed cases of swine flu in California, including the five in San Diego County, five in adjacent Imperial County and one in Sacramento, said Dr. Gil Chavez, deputy director of the state's Center for Infectious Diseases.

Most of the swine flu cases in California were mild, officials said, noting that only two people -- both in Imperial County -- had to be hospitalized, and they both had pre-existing conditions that put them at higher risk.

"So far, the disease has been fairly mild, and like any influenza season, we expect this to last for weeks," said Bonnie Sorensen, chief deputy director of the state Department of Public Health. "As we move along and find out more about this virus, our activities and our responses will change."

Sorensen said state health officials have been planning to combat a threatened pandemic disease for more than a decade.

Dr. Mark Horton, director of the California Department of Public Health, said said about one-fourth of the federal stockpile of 5 million courses of vaccines targeting the disease have been sent to Sacramento for possible distribution to local jurisdictions, if needed.

Gov. Arnold Schwarzenegger moved to calm Californians' fears. "The bottom line is that we are prepared," Schwarzenegger said, noting the activation of a joint emergency operations center -- a collaborative effort involving the state public health department and the California Emergency Management Agency.

"Public safety is our number one priority," the governor said while attending the Milken Institute's Global Conference at the Beverly Hilton in Beverly Hills.

The federal government declared a national public health emergency on Sunday, although there have only been about 40 confirmed cases of swine flu in the United States so far, and those cases were reportedly mild.

But that's not the case in Mexico, where more than 2,000 people have caught the disease and at least 149 have apparently died from it.

Swine flu is a respiratory illness usually transmitted to humans by pigs, but public health officials are concerned about a possible pandemic because the new strain appears to be spreading from human to human. The illness is characterized by the same type of symptoms associated with seasonal flu.

When U.S. Homeland Security Secretary Janet Napolitano announced the nationwide health emergency on Sunday, she added that it "sounds more severe than really it is."

"This is standard operating procedure and allows us to free up federal, state and local agencies and their resources for prevention and mitigation," she said.

The drugs Tamiflu and Relenza are believed to have been effective in fighting the disease, and the federal government is releasing about a quarter of its stock of the medicines to the states.

At a news conference Sunday in San Diego, state Superintendent of Schools Jack O'Connell said parents should not be concerned about sending their children to class.

"Our schools in California are safe," O'Connell said. "We want to make sure our parents and professional educators do everything they can to keep our schools safe."

He said local school administrators can download a free "Keep Our Schools Healthy" toolkit that includes sample letters to send home to parents and posters to place on campuses to remind children about proper hygiene. The toolkits come in multiple languages, O'Connell said.

To keep the outbreak in perspective, only a few children out of a state enrollment of 6.3 million students have been infected, he said.

The original four people in San Diego County who came down with the disease were two boys ages 7 and 10 and a 54-year-old man and his 16-year-old daughter, the county's public health officer said.

The cases were mild and the symptoms were the same as with the "seasonal flu," Wooten said.

"It's certainly possible that individuals throughout the county have already been infected with the swine influenza virus and didn't realize it and didn't get tested," Wooten said.

People should handle the swine flu like any other flu infection -- stay home and only seek treatment if necessary, she said. Wooten said two San Diegans died in the recent flu season, but not from swine flu.

An estimated 36,000 people in the United States die annually from the seasonal flu, she said. Testing is the only way to differentiate between the swine flu and other flu strains, Wooten said.

Swine flu cases have also been confirmed in New York, Ohio, Texas and Kansas.

Medical officials recommend frequent washing of hands for at least 20 seconds with soap and water, covering your mouth and nose when coughing or sneezing, and remaining home when you get sick.

The CDC has issued an outbreak notice for Mexico, and federal officials advised Americans to avoid unnecessary travel to that country.

In Mexico City, people have taken to wearing surgical masks, and the government has closed schools and canceled public events, including church services, in an effort to slow the spread of the disease.