The issue focused on what the United States is doing on the ground to try to prevent the spread of the virus and what its potential consequences will be, said Dr. Thomas Frieden, the president of the CDC, in an interview on the program "World News Live."

The outbreak, which has killed more than 4,500 people so far and affected about 100,000 people worldwide, also has drawn criticism for the lack of medical resources available for victims, and for the way it is managed by the federal