LOS ANGELES " With the number of California swine flu cases growing Monday, health officials urged residents to take precautions and report symptoms but sought to assure them the danger of contracting the disease is low.
Most people went about their business as usual, but others like Maria Whipple of San Diego were anxious about the outbreak that has claimed nearly 150 lives in Mexico. She donned a surgical mask as she returned home from a business trip in Tijuana.
"People think this is a joke. It's not a joke. I'm worried about it," Whipple said.
The state had 13 confirmed cases of swine flu, with five each in San Diego and Imperial counties and three in Sacramento County, according to Dr. Gil Chavez, deputy director for the state Center for Infectious Disease.
"The outbreak is a call to action and communication and cooperation on every level," Gov. Arnold Schwarzenegger said at a Beverly Hills news conference. He said the state was prepared and that public health authorities were working in conjunction with state emergency management officials.
With 149 suspected swine flu deaths in Mexico " where schools have been closed nationwide " the disease has captured international attention, but California officials are trying to inform the public without causing a scare. While 48 cases have been confirmed in the United States, none have been fatal.
"So far, the disease has been fairly mild and like any influenza season, we expect this to last for weeks as we move along and find out more about this virus," said Dr. Bonnie Sorensen, chief deputy director of the California Department of Public Health.
The state is also investigating other cases, including two "clusters" of patients with influenza-like symptoms in Santa Clarita, Calif. Those test results are expected to come back later this week.
Most of California's cases occurred in counties that border Mexico but officials said the first seven cases reported did not appear to be connected directly to Mexico. All the victims said they did not travel to Mexico and relatives in that country did not visit recently.
At the San Ysidro border crossing where about 40,000 vehicles enter the U.S. daily from Tijuana, some who crossed the border on foot wore surgical masks.
Sid Diaz, 76, from Indian Wells, Calif., did not let swine flu fears interfere with a cross-border dental appointment; Diaz wore a mask while visiting Tijuana to pay $300 for a gold filling. The same dental work costs $1,100 in the U.S.
"Everyone told me not to come," he said. "I'll take a chance, if I can save about $800."
Sacramento County officials reported Monday night that two more seventh-graders from St. Mel School in Fair Oaks have tested positive for swine flu, making three students in all from the school.
Tests on a fourth student, who reported feeling ill after a vacation in Mexico, came back negative Monday night.
All of the students' symptoms are mild. The 275-student school will be closed until at least Thursday.
An unconfirmed illness involving a student at Our Lady of the Assumption School in Claremont led to students being sent home early Monday for disinfection of the campus in eastern Los Angeles County. A private school in Mira Mesa was also closed after six teachers became ill, San Diego County health officials said. Tests were being conducted to determine if the teachers contracted swine flu.
Doctor's offices and clinics fielded extra calls Monday from panicked patients.
Dr. Keith Klein of Beverly Hills said his staff was inundated with calls.
"We can't handle the load of people calling. They are all panicked. They all want to come in for the slightest thing," said Klein.
Low-cost health clinics serving uninsured and poor asked patients to alert the front desk if they had flu symptoms.
"Clinics are more likely to start seeing these cases precisely because so many of our patients go back and forth to Mexico and have contact with people who do," said Dr. John Murphy, associate medical director for La Clinica de La Raza in Northern California.
California Superintendent of Public Instruction Jack O'Connell said schools were safe.
"We're taking precautionary steps, working closely with families, with parents," he said, adding that hand-washing was being promoted to students and parents.
He said that currently there was no need to close schools in California because of the small number of cases compared to the state's nearly 6.3 million students.
Los Angeles International Airport spokeswoman Katherine Alvarado said the airport was posting signs with sanitation and public health tips. Restrooms were being sanitized twice an hour, with special attention paid to door knobs and handles.
Passengers arriving from Mexico said airport workers there were handing out face masks and health information.
Martha Reyes, 38, of Los Angeles returned from Guadalajara with her 17-year-old son Julian after 10 days caring for her mother-in-law who has a heart condition. Reyes said she didn't find out about the swine flu until Sunday.
"I'm concerned because I don't know how serious it is. We've been washing our hands more frequently and not having contact with strangers," said Martha Reyes.
Associated Press Writers Garance Burke in Fresno, Michael R. Blood in Beverly Hills, Lorinda Toledo and Alicia Chang in Los Angeles, Amy Taxin in Orange County and Samantha Young in Sacramento contributed to this report. AP Writer Elliot Spagat and AP Photographer Lenny Ignelzi in San Diego reported from San Diego.