Health workers push a wheeled stretcher holding a newly admitted Ebola patient, 16-year-old Amadou, in to the Save the Children Kerry town Ebola treatment centre outside Freetown, Sierra Leone, December 22, 2014. REUTERS/Baz Ratner/Files

By Umaru Fofana

FREETOWN (Reuters) - Medical charity Medicins Sans Frontiers (MSF) has opened the first care centre in the current Ebola epidemic for pregnant women, whose survival rate from the virus is virtually zero, the charity said on Saturday.

There is currently one patient in the clinic, which is perched on a hill in the compound of a disused Methodist boys high school in the Sierra Leone capital.

More than 20,700 people have been infected with the virus in Guinea, Sierra Leone and Liberia since it began a year ago and at least 8,200 people have died, according to World Health Organization figures.

The rate of transmission has slowed in Guinea and Liberia and there are signs it is starting to ebb in Sierra Leone.

Women are particularly vulnerable to a disease spread through direct contact with infected people and with the corpses of victims, because women often care for sick family members, said MSF Field Coordinator, Esperanza Santos.

"Pregnant women (with Ebola) are a high risk group so they have less chance than...than the rest of the population," she told Reuters. The charity has played a leading roll in the fight against the virus.

Medical authorities say it is unclear why the survival rate for pregnant women is lower than for other patients but early testing and rapid treatment will help lower mortality rates.

Ramatu Samura's story illustrates issues facing pregnant women. The 16-year-old miscarried when she first contracted Ebola, but has recovered after treatment at MSF's Kingtom Care Unit maternity ward in northwest Freetown.

Survivors cannot contract the same strain of the virus and Samura is now at looking after her baby niece and the baby's mother, both of whom are being treated for the virus.

Samura said she bled for two hours and miscarried when she arrived at the care unit. She only knew she was pregnant after she miscarried and survived partly because the pregnancy was at an early stage, hospital sources said.

Sierra Leone's first confirmed Ebola case was last May 24 when a pregnant woman was brought to the public hospital in the eastern town of Kenema from the border district of Kailahun. She miscarried and died, infecting her nurses.

(Reporting by Umaru Fofana, Editing by Matthew Mpoke Bigg and Angus MacSwan)