Dr. Dora Anne Mills, who was Maine’s top doctor as head of the Maine Center for Disease Control and Prevention for nearly 15 years, was fired from her new job Wednesday, sources say.

Mills, who was medical director for MaineCare,  declined to comment Wednesday.

“I’m surprised,” said Ed Miller of the American Lung Association in Maine. “Dora is a competent public health person. We were hoping she’d bring that perspective to the MaineCare program looking at ways to improve the health of that population and reducing costs.”

Mills was director of the Maine Center for Disease Control and Prevention for nearly 15 years under Govs. Angus King and John Baldacci. As the head of the Maine CDC, “she was one of the top health officers in the country,” Miller said Wednesday. “She really propelled public health in Maine to a front page story. She spoke well to the public health community, and spoke well to every day people in Maine. They looked to her for leadership on tough health problems. She provided that leadership.”

Mills helped Maine decrease the smoking rate from one of the worst states in the country to one of the best, Miller said, adding she did much to protect people from second-hand smoke.

In December Mills said she was leaving the CDC saying it was time for a change. Becoming medical director of MaineCare would allow her to oversee and monitor the quality of health care delivery, with the goal of improving the health of people on MaineCare, she said then. It would allow her to call on her experience practicing medicine and being a public health director, she said.

MaineCare provides health coverage for 340,000 low-income and disabled people, about 26 percent of the state’s population. Mills said in December she looked forward to working with the Gov. Paul LePage’s administration, making sure MaineCare “is as efficient and effective as possible.”