A U.S. doctor was diagnosed with Ebola in Sierra Leone and treated at Emory University's biocontainment unit in Atlanta without the public finding out.

"As a result of the virus, my condition worsened and I became critically ill after I arrived at Emory," the anonymous doctor said in a statement. "Through rigorous medical treatment, skillful nursing, and the full support of a healthcare team, I am well on the way to recovery."

The male doctor, who was working for the World Health Organization when he became infected, is staying anonymous for now, but he plans on talking publicly about Ebola once he is completely recovered.

He was discharged from the hospital to an undisclosed location, Emory said in a statement.

His illness comes as a surprise, as it wasn't watched as closely as the other Americans treated for Ebola in the U.S.

Emory University treated most of the American Ebola victims including Dr. Kent Brantly and Nancy Writebol - both who have survived. Emory is currently treating Dallas nurse Amber Vinson, who was infected while treating the only U.S. victim to die from the virus.