Dr Tim O'Dempsey talks to Newsround
29 August 2014 Last updated at 12:06 BST
A British man, William Pooley, is being treated for the Ebola virus back here in the UK after catching it working in Sierra Leone.
Doctors wanted to make sure he's given the best treatment possible which is why he was flown back to London.
Dr Tim O'Dempsey told Newsround what it's like to work in such a difficult environment.