Kevin Brantly, (L) who contracted the deadly Ebola virus, thanks Bruce Ribner, medical director of Emory's Infectious Disease Unit during a press conference at Emory University Hospital in Atlanta, Georgia, Aug 21, 2014. The American doctor along with a second American aid worker who contracted Ebola treating victims of the deadly virus in Liberia have recovered and were discharged by the Atlanta hospital that treated them with an experimental drug. [Photo/Agencies]