
Dr. Margaret Chan, chief of the UN's World Health Organization (WHO), is seen on a monitor as she speaks during a press briefing at the UN headquarters in New York, on Sept. 2, 2014. With the "largest and most severe" Ebola virus outbreak advancing in West Africa, the battle against it is losing ground but "this outbreak can and will be controlled," UN officials said Tuesday. (Xinhua/Niu Xiaolei)