Atlanta ? The head of the federal government’s public health agency is stepping down, according an e-mail sent Friday night to federal employees.

Dr. Julie Gerberding has resigned as director of the Atlanta-based U.S. Centers for Disease Control and Prevention, and will be replaced on an interim basis by a deputy as of Jan. 20, the day President-elect Barack Obama is inaugurated.

Although an HHS housecleaning has been expected with the new administration, Gerberding’s fate was somewhat unclear.

The first woman to head the agency, Gerberding led the CDC through a post-Sept. 11 world of bioterrorist fears and was considered an effective communicator with legislators and the public.