Samaritan's Purse is asking for prayers after one of its doctors tested positive for Ebola.
Dr Kent Brantly is Medical Director for the Samaritan's Purse Ebola Consolidated Case Management Center in Monrovia, Liberia, one of the countries affected by the outbreak in West Africa.
The deadly virus has so far killed 660 people and has now reached Nigeria, with the country's health minister saying border controls are on "red alert" after the first death there.
Dr Brantly is now undergoing treatment at a Samaritan's Purse isolation centre at ELWA Hospital.
Despite his infection, Samaritan's Purse confirmed it would not halt medical operations at the Ebola Case Management Centers.
It is working to treat those infected and prevent the further spread of the virus in cooperation with the Centers for Disease Control, the World Health Organisation, the Liberia Ministry of Health, and other global health authorities.
Samaritan's Purse is asking people to pray for Dr Brantly, his wife and two children.
"Samaritan's Purse is committed to doing everything possible to help Dr Brantly during this time of crisis," the organisation said.
"We ask everyone to please pray for him and his family."