There is a particular sense of urgency in this case because half of the patients who may have been exposed are newborns. Kaiser officials do not know exactly when, but they believe one of their maternity ward nurses in San Francisco developed active tuberculosis as early as March.
Now, anyone who may have had contact with the nurse is being asked to come in for testing. The list includes 960 infants, 960 mothers and 115 health care workers.
"The reason why we're going to feel this is going to protect our patients and our employees is that prevention of development of the active disease is the best medicine for this," said Dr. Stephen Parodi MD, Kaiser's chair of infectious diseases.
Tuberculosis is a bacterial airborne disease that attacks the lungs. So far, one health care worker has tested positive. As for Kaiser's patients, San Francisco's Department of Public Health believes most of them likely did not spend enough time with the nurse to contract the disease. Still, there is a high level of concern, especially because newborns are involved.
"Because their immune system is brand new and actually inadequate, if they do get infected with TB they can end up with very bad forms of tuberculosis," said Masae Kawamura MD, San Francisco director of tuberculosis control.
The nurse worked the nightshift and like all health care workers, she underwent an annual health screening. Public health workers say she did show symptoms of tuberculosis, but not every person does.
Luther McCay of Richmond contracted TB two years ago and he says his cough did not seem serious.
"I just thought it was just a cold. And you wouldn't know the symptoms if you've never had TB. That's why it's so important that this is being put out in the forefront," said McCay.
The annual screening for health care workers complies with CDC guidelines, but because of this TB scare, Kaiser is looking at whether it needs to modify its screening procedures.