Hospital officials are contacting patients who came in direct contact with the woman and requiring testing for employees who had close contact while the woman worked at Boston Medical Center, the Veterans Affairs hospital's West Roxbury campus, Brockton Hospital and Cape Cod Hospital.

Authorities said Thursday that the surgical resident was contagious for six months and may have exposed more than 2,000 patients at the hospitals. Officials said, however, the risk of transmission to patients and employees was low.

Surveillance and Tracking

Dr. Michael Charness, chief of staff at the VA Boston Health Care System, said the health care facilities are reviewing their procedures to ensure this doesn't happen again.

"As this is analyzed by each institution, we recognize that there are aspects to our surveillance and tracking that could be improved," he said. "We will tighten up our systems."

According to a memo prepared by the Department of Veterans Affairs for members of Congress, the surgical resident contracted TB sometime between June 2003 and June 2004.

After a positive skin test, she was referred to the Boston Public Health TB clinic by Boston Medical Center, but never showed up for her July 2004 appointment for a chest X-ray.

Treated for Pneumonia

The memo said she first showed symptoms in January, but it is not clear whether she revealed the earlier skin test. Other tests were negative, so she was treated for pneumonia.

The resident then developed a cough and other symptoms in mid-May, and a chest X-ray on June 2 and additional tests revealed infectious TB. No information on how she contracted the disease has been released.

Tuberculosis is a disease caused by bacteria that usually attacks the lungs and can cause weakness, weight loss, fever and night sweats. Health authorities have said the risk of anyone being infected is low.