London - Queen Elizabeth II will pay tribute in her annual Christmas Day broadcast on Thursday to the "selflessness" of medical staff and aid workers fighting the Ebola epidemic.She will say how "deeply touched" she was by the volunteers who have gone to work in areas affected by the deadly virus, according to extracts released ahead of the broadcast."I have been deeply touched this year by the selflessness of aid workers and medical volunteers who have gone abroad to help victims of conflict or of diseases like Ebola, often at great personal risk," the 88-year-old queen will say.The virus has killed more than 7 500 people, the vast majority in Sierra Leone, Guinea and Liberia.People caring for the sick or handling the bodies of people infected with Ebola are especially exposed to the virus and 365 healthcare workers have died, most of them local staff.A British health worker who survived Ebola will be delivering his own message to the nation after being chosen to give Channel 4's "Alternative Christmas Message".William Pooley, a nurse who decided to return to Sierra Leone after receiving treatment in Britain, will call for greater global action against the virus."I don't want to make you feel guilty but I would like you to think just for a few minutes about what you could do to help," the 29-year-old will say in a message filmed at Connaught Hospital in Freetown."This is a global problem and it will take the world to fix it. What a wonderful Christmas present that would be."The queen's message is an annual event, broadcast on BBC television and radio after lunch, and watched by millions of people in Britain and across the Commonwealth.It is one of the few speeches that she writes herself, rather than with government ministers.For the past two decades, independent television station Channel 4 has selected a figure in the public eye to deliver an alternative message, which is broadcast after the queen.US whistleblower Edward Snowden gave the message last year, and previous speakers included Iranian president Mahmoud Ahmadinejad and French animal rights campaigner and actress Brigitte Bardot.The Archbishop of Canterbury, the spiritual leader of the Anglican faith, also highlighted the horrific nature of the Ebola outbreak in his Christmas message, noting how it was spread by people touching each other.It was "striking people down above all when they exhibit their deep compassion for the human dignity of others through touching and holding them, or through washing their bodies after death", Justin Welby noted."The acts of love have become the means of infection and death," he said.