Twelve health workers in the Democratic Republic of Congo have died of Ebola, the minister for public health says.
They are part of a group of 44 health workers who have been infected with the virus.
This is a worrying development for those working to contain the virus, which has now spread to dozens of towns in eastern DR Congo.
Since the outbreak began in July, 273 people are believed to have died from Ebola.
While an experimental vaccine - administered to more than 40,000 people - has helped saved lives according to officials, the presence of armed groups in the affected provinces of North Kivu and Ituri continues to make the response an ongoing challenge.