Ebola chief: Global effort must increase

UN expert 'optimistic' but warns worst may lie ahead if virus rebounds

The United Nations' Ebola chief said an extraordinary global response over the past month has made him hopeful the outbreak could end in 2015, although he cautioned that the fight to contain the disease is not even a quarter done.

"Until the last case of Ebola is under treatment, we have to stay on full alert," Dr. David Nabarro said on Thursday in an interview with The Associated Press. "It's still bad."