The numbers of probable and confirmed cases of swine flu continued to rise in the Bay Area but state officials say the increase was anticipated.
"We are fully expecting to see an increase in numbers and an increase in severity (of the cases)," said California Department of Public Health Director Dr. Mark Horton.
He added, though, that the increase in cases in both California and the nation does not mirror the greater number of cases in Mexico, where the contagious virus was first reported in March.
"We have small numbers," Horton said. "We're not seeing the kind of severity they're seeing in Mexico."
Fear mounting in response to the swine flu outbreak that as of Thursday afternoon is known to have sickened 16 Californians is likely due to Mexico's much deadlier reaction to the virus.
"We have a neighbor very close to us to the south who is having a different experience," Horton said. "It's still very early in the game. This is a novel virus."
Local health officials at news conferences throughout the Bay Area Thursday also encouraged the public not to panic.
Dr. Scott Morrow with the San Mateo County Health System said at a news conference that most cases of swine flu have not been serious and there is a good chance there are many more undocumented, also mild cases.
San Francisco Mayor Gavin Newsom echoed Morrow's statements, asking people to stick to the facts and keep calm after announcing the city's first case of swine flu Thursday.
"We've asked in out letter to parents to monitor their kids and not attend large group activities in those schools," Santa Clara County Health Officer Dr. Marty Fenstersheib said.
More than a dozen other swine flu cases have popped up in the Bay Area this week, but most if not all were considered mild and many have since recovered.