Eight new cases of influenza linked to the Harvard Dental School have been deemed by local and state health officials “probable” infections of H1N1 “swine flu,” according to an announcement made by the Boston Public Health Commission at a press conference Friday afternoon.

The announcement raises the total number of possible cases in the Boston area to nine, adding to the original diagnosis of a Dental School student that was announced last week.

Of those nine, two cases tested as Type A influenza accompanied by “acute febrile respiratory illness,” meeting the criteria for swine flu diagnosis published by the national Centers for Disease Control in Atlanta.

Final confirmation of a swine flu diagnosis is pending additional test results from the CDC, said David S. Rosenthal ’59, director of Harvard University Health Services. Rosenthal also noted that no additional cases had been identified over the weekend, a finding that seems to indicate that the possible epidemic may have been contained.

Following recommendations from the Public Health Commission, the Dental School—along with the Harvard Dental Center—will remain closed until May 6, when the transmissibility period for the current patients will have passed.

“This is a unique situation because the [infected] students see patients and, in this group of nine students, there was contact with patients,” said Barbara Ferrer, the executive director of the Commission.

Ferrer added that her office also recommended that the Harvard Medical School suspend its clinical rotations until May 6 due to its close relationship with the Dental School.

Rosenthal said that the Medical School has complied with Ferrer’s recommendations on clinical rotations.

At the press conference, Anita Barry, director of the Infectious Disease Bureau at the Boston Public Health Commission, said she believed that only a small number of patients could have been exposed to the infected students, explaining that the hygienic masks used during treatment as well as the low-volume caseloads typical of dental rotations would have minimized risk.

The Dental School has faced a precautionary closure since last Thursday, after one of the School’s students was diagnosed with a case of influenza symptomatically similar to previously observed swine flu cases. According to Ferrer, that student had been in close contact with an unidentified individual not living in Boston who fell ill after recent travel to Mexico.

Both Ferrer and Rosenthal stated that all nine of the diagnosed students are making full recoveries from within their homes, where they have been asked to remain until their period of transmissibility passes.

Additionally, Rosenthal emphasized that despite the low overall severity of the recent case-cluster, the Harvard health community will remain vigilant.

“We just have to continue good hygiene and advise people who are sick to contact their doctor,” he reiterated.

Rosenthal said that a reevaluation of the schools’ closures will be made on Wednesday after further clinical review.

—Staff writer Edward-Michael Dussom can be reached at emdussom@fas.harvard.edu.