This is now by far the worst ebola outbreak the world has ever seen, with 3,400 people dead, and 7,500 confirmed cases, though the true figure is thought to be much higher. The deadliest until now saw 280 people die in 1976 in Zaire, now Congo.
Most of the deaths have happened in Guinea, Sierra Leone and Liberia, with the World Health Organisation expressing concern at the poor state of the health services in those countries. Liberia says it is short of ambulances, and that it has only a third of the number of treatment centres it needs.
Now alarm is sweeping through Spain after a nurse who had been treating two missionaries who caught ebola in Africa, was found to be infected herself. It had been hoped that the stringent safety precautions available in modern hospitals would prevent the virus spreading.