An American doctor who was exposed to Ebola while in Sierra Leone has been flown to the United States.
The doctor was flown to a regional airport in the eastern state of Maryland Sunday and walked off the plane wearing a white protective suit.
The infectious disease chief at the National Institutes for Health near Washington would not discuss details about the patient, but said that in general, an exposure to Ebola doesn't necessarily mean someone will become sick.
In a statement issued Saturday, the NIH said the patient will be admitted to the NIH Clinical Center for observation and to enroll in a clinical study. The NIH also said the physician will be in a special isolation unit out of "an abundance of caution."
The NIH did not release any additional details about the person.
Four other American aid workers who were infected with Ebola while volunteering in the West African outbreak have been treated at hospitals in Georgia and Nebraska.
One remains hospitalized while the others have recovered.