Some Long Island parents fear their children may have been exposed to swine flu from students at a Queens prep school.

Sports teams at St. Dominic High School in Oyster Bay played games against St. Francis Prep, where cases of swine flu were reported. Teams from Mineola High School also played against the Queens school. Mineola parents are receiving letters and automated phone calls from the district.

Meanwhile, Nassau officials have announced the first confirmed case in the county. In Suffolk County, health officials are investigating four cases. They took samples from four people in Amityville and sent them to the state health department for further testing.

The North Shore-Long Island Jewish Health System has activated its emergency response plan across its 14 hospitals and set up a command center in Syosset. Those working at the command center are monitoring patterns including sick patients, where those people are from and what symptoms they are showing. If necessary, LIJ will distribute resources, ramp up staffing and report any findings to county and state health departments.

Terry Lynam, of North Shore LIJ, says more than 350 people have gone to LIJ emergency rooms with flu-like symptoms since illnesses were first reported at St. Francis over the weekend.

There are at least 64 confirmed cases of swine flu in the United States, including 28 students at the Queens prep school. Swine flu is suspected in up to 152 deaths in Mexico, with 20 deaths confirmed so far in that country.

The virus, which began in Mexico, has spread to at least six other countries. The World Health Organization has raised its alert level to Phase 4, two steps below pandemic stage. New Zealand has confirmed the virus in 11 people who recently returned from Mexico, and a man in Israel has also been confirmed with swine flu. Spain confirmed its second case Tuesday.

None of the cases outside Mexico have been fatal.

Symptoms of swine flu include a fever of more than 100 degrees, coughing, joint aches, severe headache and, in some cases, vomiting and diarrhea.

AP wire services contributed to this reportWorldHealth OrganizationCDCPandemicFlu.govWorld Health Organization NYS Swine Flu Hotline: 1-800-808-1987