The official says there are another 17 probable cases in New York City.
The outbreak is occurring at a school in Queens where about 150 students came down with symptoms.
The virus apparently resulted from a spring break trip to Mexico by students at the school.
A school in Rye, New York, has also shut down as a precuation. CLICK HERE for more info on that story.
In Mexico, health officials say a strain of swine flu has killed up to 149 people and sickened more than 1,600.
New York officials said the flu strain discovered in the patients here is similar to the one in Mexico, but not as severe at this point. They are still conducting tests to investigate the strain in New York.
St. Francis is the largest private Catholic high school in the nation, with 2,700 students. The school canceled classes on Monday and Tuesday in response to the outbreak.
Parent Jackie Casola said Sunday that her son Robert Arifo, a St. Francis sophomore, told her on Thursday that a number of children had been sent home because of illness. On Friday, he said hardly anyone was in school.
Casola said she expected to keep him home from school on Monday, even if it was open. He hasn't shown any symptoms, but some of his friends have, she said, and she has been extra vigilant about his health.
"I must have drove him crazy, I kept taking his temperature in the middle of the night," she said.
Swine flu is a respiratory infection caused by influenza type A viruses that regularly cause outbreaks of influenza in pigs. People do not normally get swine flu, but human infections can occur. Human cases typically involve people who have had direct contact with pigs, but likely person-to-person transmission has now been reported in California, Texas, Mexico and New York City. Again, the cases in Mexico have had a high fatality rate, but the confirmed cases in the U.S. have been mild and all patients have recovered without treatment.
The symptoms of swine flu in people appear to be similar to the symptoms of regular seasonal flu and include fever, cough, sore throat, body aches, headache, chills and fatigue. Some people have reported diarrhea and vomiting as well. New Yorkers experiencing severe symptoms, such as difficulty breathing, should seek health care and treatment. Otherwise, the health department recommends at-home care.
The most effective way to lower the risk of influenza transmission is for people with symptoms to stay home. All New Yorkers should cover their mouths when they cough. Additional precautions:
Swine influenza cannot be transmitted from eating pork or pork products.
For facts about influenza, and more information about swine flu, please visit the health department and CDC Web sites. Some specific resources:
From New York City Health Department
Facts about flu
From Centers for Disease Control and Prevention
General information about swine flu
Swine Flu Case Definitions
Swine Flu Infection Control and Patient Care
Preventing the Flu
NEW YORK AND TRI-STATE AREA NEWS