Dr. Bruce Ribner, the Emory University Hospital epidemiologist who oversees the isolation unit at the hospital set up to treat patients exposed to certain infectious diseases, speaks at a news conference, Friday, Aug. 1, 2014, in Atlanta. Ribner said Friday two American aid workers infected with the Ebola virus in Africa will be treated at the hospital.

David Goldman / AP

Dr. Bruce Ribner, the Emory University Hospital epidemiologist who oversees the isolation unit at the hospital set up to treat patients exposed to certain infectious diseases, speaks at a news conference, Friday, Aug. 1, 2014, in Atlanta. Ribner said Friday two American aid workers infected with the Ebola virus in Africa will be treated at the hospital.