The last known Ebola patient in the United States, a New York doctor who contracted the virus while treating infected people in West Africa, was released from the hospital on Tuesday after being declared cured.

Craig Spencer, an emergency room doctor in New York, appeared at a press conference flanked by Mayor Bill de Blasio to announce that he had been discharged from Bellevue Hospital -- one of a handful of US medical facilities designated to handle Ebola.

"New York City's first and only Ebola case is successfully treated. Dr Spencer is Ebola-free and New York City is Ebola-free," De Blasio proclaimed at the hospital, to cheers and applause.

Spencer, 33, had been admitted to the hospital three weeks earlier after returning to the United States from Guinea, which along with Sierra Leone and Liberia is one of three hard-hit West African countries where the often fatal disease is raging.

He returned to the United States on October 17, flying into John F. Kennedy International Airport, after returning from several weeks volunteering with the Doctors Without Borders group.

Spencer's case stirred fears because he traversed New York in the days following his return, using the subway and a taxi, dining in a popular restaurant and going bowling with friends, before falling ill and isolating himself.

He said he was grateful for the high-quality medical care he received during his illness, and urged that more be done for those suffering from Ebola in Africa.

"Today I am healthy and no longer infectious. My early detection reporting and now recovery from Ebola speaks to the effectiveness of the protocols that are in place for health staff returning for from West Africa," he said.

"While my case has garnered international attention, it is important to remember that my infection represents but a fraction of the more than 13,000 reported cases to date in West Africa... where families are being torn apart and communities are destroyed."

In what has become something of a ritual when public officials pronounce Ebola patients cured, De Blasio gave Spencer in an hug of appreciation for his selfless volunteer work with Ebola patients in Africa -- and to demonstrate that the public need have no fear of contracting the disease from him.

"It is a good feeling to hug a hero, and we have a hero here in our midst," de Blasio said, adding that Spencer deserved praise as "someone who served others, no matter how much danger."

"He has been an inspiration throughout the challenges he's faced, and by the way, Dr Spencer showed us what it means to help your fellow human," de Blasio said.

Some 5,000 people have died from Ebola, mostly in West Africa, where underfunded health systems have contributed to the rampant spread of the disease.