An American doctor helping to treat Ebola in Liberia has contracted the virus.
Dr Kent Brantly, who works for the charity Samaritan's Purse, reportedly recognised his own symptoms and confined himself to an isolation ward, NBC News reported.
A spokeswoman for the charity said Dr Brantly's wife and two children had been living with him in Africa but are currently in the US.
The deadly illness has killed more than 660 people across west Africa and it has now spread to Nigeria after the death of a Liberian man in Lagos.
More than 160 staff will work in a UK-funded facility in Sierra Leone which is due to open in October.
UK trials of a vaccine for the Ebola virus began today - but some experts complain that the response has been a long time coming.
A Swansea doctor who took leave to treat Ebola patients in Africa, is back on the wards after three weeks in isolation.