Emory University Hospital officials say some patients and employees have been exposed to tuberculosis (TB) between November 7, 2010 and April 17, 2011.In a statement released Thursday, officials with the hospital say 680 patients and 100 employees have been contacted who were exposed by the infected person. They will be provided post care free of charge at each patient's local county health department. Hospital officials say the hospital takes many steps to ensure a safe place for patients and employees. However, hospital officials discovered that a hospital staff member, who unknowingly carried the infection, came in contact with the patients and employees.