The Ebola outbreak in West Africa is spreading faster than efforts to control it, World Health Organization (WHO) head Margaret Chan has said.
She told a summit of regional leaders that failure to contain Ebola could be "catastrophic" in terms of lives lost.
But she said the virus, which has claimed 728 lives in Guinea, Liberia and Sierra Leone since February, could be stopped if well managed.
Ebola kills up to 90% of those infected.
It spreads by contact with infected blood, bodily fluids, organs - or contaminated environments. Patients have a better chance of survival if they receive early treatment.
Initial flu-like symptoms can lead to external haemorrhaging from the eye...