San Diego and Riverside counties declared states of emergency Wednesday as confirmed and suspected cases of the swine flu in the two jurisdictions climbed to 12.

Tom Christensen of the San Diego County Health Department said eight swine flu cases in San Diego County had been confirmed as of midafternoon Wednesday.

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Riverside County health officials reported four suspected cases and, in an abundance of caution, they closed three schools for a week.

State health officials said they are recommending a seven-day closure of any school where a student has been diagnosed with the illness.

At the Marine Air Ground Combat Center at Twentynine Palms in the Mojave Desert, a Marine was diagnosed with the virus, prompting service officials to quarantine him. The service also ordered 30 other Marines he came into contact with to be quarantined for five days as a precaution.

The county proclamations follow Gov. Arnold Schwarzenegger's declaration of a state emergency on Tuesday. The moves essentially cut red tape to free up funding and streamline efforts to try and keep the outbreak in check.

San Diego County Supervisor Dianne Jacob said residents should remember that 36,000 people nationwide died from the flu last year.

"Our citizens should not be worried to any greater extent than they are for any flu outbreak," she said. "We're doing everything we can to prevent the spread."

The number of confirmed swine flu cases in the U.S. as of Wednesday was 93. California has 14 confirmed cases and 29 probables.

Another suspected case was reported at San Diego State University, where a campus health official said if it is confirmed, classes may be canceled.

Four people in Riverside County have tested positive for what appears to be the swine flu, including a 5-year-old girl and an 87-year-old woman. The woman was hospitalized and is recovering, county officials said.

"With these cases, we now believe swine flu is in the community, but we do not know the extent to which it exists. This is a time for precaution, not panic," said Dr. Eric Frykman, Riverside County public health officer.

Frykman said each of the four tested positive for a strain of influenza that is "a strong indicator of swine flu."

The elderly woman who had to be hospitalized had recently traveled to Baja California. The recent travel history of the child, who is not related to the 87-year-old woman, is under investigation, officials said.

The two other cases include a 16-year-old Corona girl and a 17-year-old Indio High School student. Both were seen at outpatient clinics, but not hospitalized. Officials are looking at the travel history of both teens. Indio High School was ordered closed until May 7 so the campus can be disinfected.

Corona's Lee V. Pollard High School and Mission Bell Elementary School in Riverside have been ordered closed until May 6.

"This is a very dynamic situation," Frykman said. "I'm not attempting to be alarmist, but this virus concerns me more than anything I've seen in many, many years. It's just a matter of time before cases start showing up here."

He said the county has roughly 20,000 doses of antiviral drugs, which would evaporate quickly in a major outbreak.

San Diego County has received 50,000 doses of antiviral drugs.

Dr. Mark Horton, director of the California Department of Public Health, said Wednesday the outbreak probably will be around for at least the next six weeks.

Horton said the recommendation that schools close for a week if a student comes down with swine flu is intended to stop the spread of the disease, which has killed 168 people in Mexico and one in the U.S.

While the traditional seasonal flu kills about 4,500 people in California each year, Horton said officials are particularly worried about the swine flu because of its uniqueness.

"It gets down to the fact that this is a novel virus and could be triggering a pandemic," he said.

No vaccine has yet been developed, leaving doctors with only Tamiflu and Relenza to treat symptoms of those who have the flu.

As the World Health Organization moved one step closer to declaring a pandemic outbreak, Rep. Duncan D. Hunter, R-El Cajon, reiterated his belief that all nonessential cross-border traffic with Mexico be suspended.

Hunter said Wednesday he believes border crossings should be limited to essential commercial traffic and people who work in the United States or in Mexico.

"The Homeland Security Department should be limiting it now," Hunter said in a telephone interview.

Tourism between Mexico and the United States should cease until the outbreak is controlled, he said.

Homeland Security Secretary Janet Napolitano disagrees with Hunter.

"Closing our nation's borders is not merited here," Napolitano said at a midafternoon briefing in Washington, echoing comments she made earlier in the day at a Senate hearing.

Closing borders would have "no impact or very little" to help stop the spread of the virus, she said.

"This virus is already in the United States," Napolitano said. "Any containment theory … is really moot at this time."

Customs agents have delayed 49 people at the border because of flulike symptoms, and 41 have been cleared so far. Test results on the other eight were not complete, according to federal officials.

The Associated Press and staff writer Teri Figueroa contributed to this report.

Contact staff writer Mark Walker at (760) 740-3529 or mlwalker@nctimes.com.

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