Speaking in Geneva, MSF President Joanne Liu said the situation was "deteriorating faster, and moving faster, than we can respond to".
Ms Liu said that although Guinea was the initial epicentre, the pace there had slowed, and other countries - particularly Liberia - were now the focus. "If we don't stabilise Liberia, we will never stabilise the region. In terms of timeline, we're not talking in terms of weeks, we're talking in terms of months. We need a commitment for months, at least I would say six months, and I'm being, I would say, very optimistic. All governments must act. It must be done now if we want to contain this epidemic," she said.
Ebola is transmitted by direct contact with the body fluids of a person who is infected. Initial flu-like symptoms can lead to external haemorrhaging from areas such as eyes and gums, and internal bleeding which can lead to organ failure. The WHO - which declared a global health emergency - recently said the risk of transmission of Ebola during air travel remained low, as the disease is not airborne. As a consequence, Kenya Airways has rejected pressure to suspend its flights to the Ebola-hit states of West Africa.
The WHO said in a statement that its staff had seen evidence that the number of reported cases and deaths did not reflect the scale of the crisis. Experts going house-to-house in Kenema, Sierra Leone, in search of infected people were discovering more cases. An 80-bed treatment centre that recently opened in Liberia's capital Monrovia filled up immediately and the next day, dozens more people turned up to be treated. Tarnue Karbbar, of the aid group Plan International in northern Liberia, said medical teams were not able to document all the cases erupting. He said many of the sick were being hidden at home by relatives, and many victims were buried before teams could get to the area.
The outbreak is also affecting the Youth Olympic Games about to start in China. The International Olympic Committee (IOC) has ruled that athletes from Ebola-hit countries will not be allowed to compete in combat sports or in the pool, and Sierra Leone and Nigeria have withdrawn from the Games.
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