Kent Brantly told of his joy at being alive after being discharged from Emory University Hospital in Atlanta, USA.
He had returned there from Liberia after succumbing to the virus with another missionary from the Samaritan's Purse organisation.
The drug ZMapp is known to have been given to six infected people and supplies are now exhausted, it was reported.
Along with the two US missionaries it went to three Liberian health workers - who may be recovering - and a Spanish priest who died.
Dr Brantly, aged 33, said: "Today is a miraculous day. I am thrilled to be alive, to be well, and to be reunited with my family. As a medical missionary, I never imagined myself in this position."
The World Health Organisation said the drug had been given to a nurse and two doctors in Liberia. The nurse and one doctor had shown a "marked improvement" while the second doctor had improved a little.
WHO said it could be calling its next summit on potential treatments for Ebola early next month.
But two experts yesterday spoke of "critical ethical principles" that should apply to the use of Ebola drugs.
Writing in The Lancet, bioethicists Professor Ezekiel Emanuel, of the University of Pennsylvania, Philadelphia, USA, and Dr Annette Rid, of King’s College London, UK, say the use of the drugs should not be confined to "well off or well-connected" patients.
They call for randomised control trials and suggest drugs should also be deployed in areas where they might help stem the spread of the virus.
Dr Rid said today: "It is more likely than not that the interventions will not improve symptoms for patients, and might even weaken them as they battle a life-threatening disease.
"Experimental Ebola treatments or vaccines should only be deployed in clinical trials, and if trials are done, they must meet ethical principles for research."
* Meanwhile the authorities in Ireland are conducting tests to establish whether a native Irish man contracted the virus.
The man is thought to have travelled to Sierra Leone to work.
Lancet 22 August 2014
Health secretary Jeremy Hunt was quoted as backing the idea.
Newspaper reports said the assistants could take on many of the roles currently undertaken by junior doctors.
According to The Times, they would examine patients, order tests, admit and discharge patients and even decide treatments. They would prepare prescriptions but a doctor would have to sign them.
The paper said they could earn up to £40,000 a year and would be science graduates who had undertaken two years of intensive training.
Mr Hunt said: "The NHS is treating record numbers of people. That’s why we are growing the workforce further with a new class of medic so busy doctors have more time to care for patients."
The revelation came in a survey of a thousand GPs.
More than 90% of doctors said they felt pressure from patients to give a prescription for coughs and colds.
And 70% of doctors said they would prescribe antibiotics because they were unsure whether infections were viral or bacterial.
The survey was conducted for the Longitude Prize, a government-backed project to stimulate new scientific discovery.
The prize is worth £10 million and is being offered this year for innovations in antibiotics - following a public vote.
The survey was conducted by MedeConnect, the market research arm of Doctors.net.uk.
It also showed 24% of GPs calling for improved diagnostic tests to help them identify bacterial infections. But 45% said they had prescribed antibiotics for viral infections knowing they would not treat the illness.
And 28% said they prescribed antibiotics several times a week, even if unsure they were needed.
A separate survey of the public by pollsters Populus found just 6% admitting they would pressurise a doctor to give them antibiotics
Tamar Ghosh, from the Longitude Prize, said: “Across the globe we need accurate point-of-care diagnostic tools to maximise the chances that antibiotics are only used when medically necessary and that the right ones are selected to treat the condition. In the next five years, the Longitude Prize aims to find a cheap and effective diagnostic tool that can be used anywhere in the world.
“We recognise that stemming the misuse and overuse of antibiotics is just one piece of the jigsaw to slow bacterial resistance to antibiotics.
"Nevertheless it’s an important step when we could be waiting many years for other solutions, including novel alternatives to antibiotics coming to the market.”
A mutant form of the virus has been discovered in a study of an outbreak that took place in the Congo in 2010.
The findings are alarming because polio has resurfaced as a threat in troublespots around the world - in spite of a global drive to eradicate it.
The German researchers confirmed that the strain they found was vaccine resistant by tests on blood samples from 34 medical students, all vaccinated in childhood.
The research was undertaken at the University of Bonn.
The researchers say the mutant strain may not yet be able to cause an outbreak on its own. The original outbreak in the Congo was halted, partly through a vaccination programme.
Researcher Dr Jan Felix Drexler said: "We isolated polio-viruses from the deceased and examined the viruses more closely. The pathogen carries a mutation that changes its form at a decisive point."
The researchers add: "We can't afford to sit back and do nothing. We need to further increase the vaccination rate and develop new, more potent vaccines. Only in this way do we have a chance of permanently vanquishing polio."
* A second study in the journal Science last night suggests using two vaccines as part of the anti-polio campaign.
The Indian researchers say that the inactivated polio vaccine is an effective booster for children given the live polio vaccine and more effective than a second shot of the live vaccine.
Robustness against serum neutralization of a polio virus type 1 from a lethal epidemic of poliomyelitis in the Republic of Congo, 2010; PNAS 18 August 2014; doi: 10.1073/pnas.1323502111
Efficacy of inactivated poliovirus vaccine in India. Science 21 August 2014 [abstract]