New York City Mayor Michael Bloomberg said Sunday federal health officials have found that eight prep school students in New York have contracted swine flu, the same flu that has killed more than 80 people in Mexico and infected 1,300 more.

“So far there does not seem to be any outbreak,” Mr. Bloomberg said. “We don’t know if the spread will be sustained. What’s heartening is the people who tested positive have only mild illnesses.”

About 100 students at St. Francis Preparatory School in Queens fell ill and some family members have also contracted the virus.

New York health officials tested samples for eight students Saturday and determined the students were probably suffering from swine flu, and the CDC confirmed the diagnosis on Sunday, Bloomberg said.

He also urged New Yorkers to stay home from school or work if they have any symptoms of the flu - but also urged people not to panic or flood hospital emergency rooms.

The Centers for Disease Control and Prevention said they expect more illnesses around the nation. So far there six cases in California, two more in Texas and two in Kansas.

The World Health Organization has warned the virus threatens to become a global pandemic, but has already begun preliminary work with laboratories to prepare a vaccine against swine flu if needed.

I believe that the world is much, much better prepared than we have ever been for dealing with this kind of situation, said Keiji Fukuda, acting director-general for health security and environment.

The past five years have put us in (the) best possible position to handle this kind of situation, he said.