The U.S. doctor who came down with Ebola after returning from volunteer work in Africa where the outbreak began has been declared free of the virus and has been released from a hospital.

Dr. Craig Spencer, 33, who treated Ebola patients as a volunteer with Doctors Without Borders in Guinea, had been in an isolation ward at Bellevue Hospital Center since he was diagnosed with Ebola Oct. 23.

"Today I am healthy and no longer infectious," said Spencer to a crowd gathered in the lobby of the hospital where he had spent 19 days.

Spencer swapped hugs with the nurses who had treated him and received one from New York City Mayor Bill de Blasio.

"Dr. Spencer is Ebola free and New York City is Ebola free," de Blasio said.

On Oct. 23 Spencer had been transported by ambulance to Bellevue after informing authorities he had a fever of 100.3 degrees.

Blood tests taken while he was placed in a secure isolation ward confirmed he had the Ebola virus.

Upon his release, Spencer urged people to concentrate not on him but on the ongoing crisis in Africa.

"Please join me in turning our attention back to West Africa and ensuring that medical volunteers and other aid workers do not face stigma and threats returning home," he said.

A few U.S. states have ordered mandatory quarantines for health workers returning to this country from the West African countries of Guinea, Liberia and Sierra Leone.

Some have called the actions counterproductive out of concerns the possibility of such quarantines might discourage potential medical personnel from volunteering to go to Africa.

Mayor de Blasio made the same point, saying the one sure way to protect New Yorkers and the rest of the world is to ensure an end to the outbreak in Africa.

While in Bellevue Spencer underwent several forms of treatment, including being given a new experimental drug and receiving blood plasma donated by a recovered and now immune Ebola patient, Nancy Writebol, a 59-year-old missionary who was infected with the virus in Liberia.

Nine cases of Ebola in the U.S. have resulted in just one death, that of Thomas Eric Duncan, who was exposed to the virus in his native Liberia and died after coming to this country.

Treatment in his case had been delayed by an initial misdiagnosis of his illness by doctors in a hospital in Dallas.

Two nurses who treated Duncan in that hospital contracted Ebola but both were treated and survived.