That brings the number of hospital workers diagnosed with whooping cough to four.

The latest staff member who has tested positive with whooping cough is a physician who worked in the hospital's emergency department on Sep. 1 and Sep. 2 between 7 pm and 7 am.

On Friday, the hospital announced that three workers were diagnosed with pertussis and may have exposed patients and visitors to the pediatric intensive care unit since August 9th to the disease.

The hospital has not identified any patients who have developed pertussis. Whooping cough is a contagious bacterial infection that usually causes a prolonged coughing illness with little or no fever.