An elderly Spanish priest infected with the Ebola virus is in a serious condition and will not receive the experimental drug ZMapp because world supplies are exhausted, Madrid health authorities said.

Manuel Garcia Viejo, 69, was taken to Madrid's Carlos III hospital last night after he was repatriated from Sierra Leone.

"The patient is badly dehydrated and his kidneys and liver are affected," said Francisco Arnalich, who oversees internal medicine at the hospital. "His situation at the moment is serious."

The hemorrhagic fever Ebola has infected at least 5,357 people in west Africa since March, mainly in Sierra Leone, Guinea and Liberia, killing 2,630 of those, according to the World Health Organization.

Garcia, who was the medical director of the Hospital Order of San Juan de Dios, was diagnosed in Sierra Leone in the Western city of Lunsar, and flown home on Sunday, after a three-day lockdown in the African country ended.

Madrid authorities said the drug ZMapp, used to treat two American aid workers and a British nurse, who all recovered, was no longer available.

Medical staff are studying various other experimental treatments including one that gives sufferers a dose of serum from a recovered Ebola victim.

Garcia is the second Spanish priest to be diagnosed and repatriated with Ebola after Miguel Pajares, who received ZMapp but died last month days after being brought back to Spain from Liberia.