He caught the virus in his native Liberia, was being kept in isolation in a Dallas hospital and receiving experimental drugs.
He was the first person to be diagnosed within the US, three American aid workers and a photojournalist contracted the virus in Liberia.
"It is with profound sadness and heartfelt disappointment that we must inform you of the death of Thomas Eric Duncan this morning at 7:51 am," a spokesman said in a statement..