Dentist's patients show no flu signs

BU representatives are attempting to locate the other two patients seen by the novice dentist last week at an orthodontics clinic operated by the university's Goldman School of Dental Medicine on its campus in Boston's South End. The trainee also is believed to have had contact with the school's 15 other junior dentists; two have symptoms that could be harbingers of the flu, officials said.

Hoping to assure the virus migrates no further, the Boston Public Health Commission and BU decided to shutter the East Newton Street clinic until Friday and declared that anyone affiliated with the orthodontics program should remain cloistered at home during that period.

The diagnosis of a probable swine flu infection on BU's medical campus emerged even as the future trajectory of the viral disease outbreak remained uncertain. The number of cases in the United States continued to climb - to 244 - and by yesterday, the germ had arrived in 19 nations.

But disease trackers derived a measure of comfort from reports showing that most Americans with the illness, which is also being referred to by its scientific name of H1N1, suffer no life-threatening symptoms. Specialists also remain intrigued by the finding that most people stricken with the disease are relatively young. In Massachusetts, for example, four of the six patients with confirmed cases are 9 to 14 years old.

"You have to ask yourself: Why are we not seeing disease in grandma?" said Dr. Anita Barry, director of the health commission's Infectious Disease Bureau. "We're simply not getting reports of disease in the elderly."

That, in many respects, is a surprise. Seasonal influenza, estimated to have a hand in the deaths of 36,000 Americans each year, disproportionately targets the old and those with impaired ability to fight disease. Perhaps, Barry speculated, older people are partially immune to swine flu, the legacy of exposure to earlier flu strains that may have carried components of the H1N1 virus.

The germ, instead, appears to be finding more fertile territory on college campuses and in some schools. The Academy of Notre Dame in Tyngsborough informed parents and the school community yesterday that a student appeared to have the H1N1 flu. Officials decided to close the elementary and high school today through Friday and asked parents and students to monitor the school website, www.ndatyngsboro.org for information.

"The health and well-being of our students, teachers, staff, and community are our top priority," said Dr. Karen Juliano, president of the academy.

In Providence, classes are being canceled today at Johnson & Wales University after three probable cases of the disease were identified. In New Hampshire, Kearsarge Regional High School will be closed today after a student fell ill. In Boston, Harvard has temporarily suspended classes at its dental and medical schools and barred those students from seeing patients in hospitals and clinics after as many as nine dental students were diagnosed with possible swine flu infections.

"We do know that people living in dormitories or group settings are in higher-risk environments for this sort of disease transmission," said Dr. Paul Biddinger, a specialist in emergency preparations at Harvard and Massachusetts General Hospital. "And much of that has to do with the fact they share common facilities: kitchen, bathroom, and the common airspace, if many people live in the same room."

Another challenge, he said, is communicating to young adults about how to protect themselves.

Investigators from Boston's health agency could establish no link between the BU dental resident with a probable case of swine flu and any of the Harvard students.

"And the [BU] student did not recently travel to Mexico and has no known contact with anyone who traveled to Mexico," said Barbara Ferrer, executive director of the Boston Public Health Commission. Mexico is the epicenter of the swine flu outbreak.

Preliminary tests conducted by the state showed that the BU resident was infected with a form of flu distinctly different from the garden-variety strains evident most years; federal confirmatory tests are pending. The trainee is at home recovering.

The BU dental trainee, whose identity was not released because of patient confidentiality rules, began feeling ill last Tuesday but continued to work at the orthodontics clinic until Thursday morning. Representatives of the university and city health agency said they believe the risk to patients was slim because dentists in the university clinic routinely wear masks and gloves that are changed between patients.

Stephen Smith can be reached at stsmith@globe.com.