A federal health official called it shameful that anyone should die of TB, which is preventable and curable.

Fewer than 1,000 people die of tuberculosis each year in the U.S. But the nurse at Chesapeake General Hospital remained undiagnosed and untreated "until it was in a very late stage," said Dr. Nancy Welch, health director in Chesapeake, a community near Norfolk.

"In this day and age, it is shameful that people should be dying of an otherwise preventable and curable disease, such as tuberculosis," said Dr. Kenneth G. Castro, director of the tuberculosis elimination division for the Centers for Disease Control and Prevention in Atlanta.

Welch said it is unknown how the nurse caught TB. Healthcare workers are known to be at high risk for the disease.

The nurse had been coughing since October but continued to work at Chesapeake until April, officials said.

Letters urging testing at a Chesapeake high school were sent Friday to about 450 to 500 patients and 250 to 300 staff and volunteers who worked in the medical surgical unit where the nurse worked, Welch said.

Donald Buckley, the hospital's president and CEO, said hospital employees are encouraged not to work when they are sick. "Employees have to accept responsibility for their own health, especially if they are healthcare workers," Buckley said.

Health and hospital officials refuse to identify the 52-year-old female nurse.

TB is highly treatable and is not casually spread. Those most at risk are people in close contact with someone who has the disease. "You're not going to get it just from walking down the street and somebody coughing on you," said one medical expert.

TB has an incubation period of months or even years from exposure to development of the disease, and it can only be spread when it is an active case.