The Ebola virus has killed thousands and it now threatens entire economies, particularly those of the West African nations hardest hit. More than 5,000 people have been infected and almost 3,000 are dead, according to the World Health Organization (WHO), which projects that the virus could infect more than 20,000 people. And with that comes the need for some serious money. The UN says West African countries need $1bn to tackle the outbreak, and of that number more than $350m has been pledged.We speak to Jim Yong Kim, the president of the World Bank, about efforts to fight Ebola, and whether he thinks it can be brought under control. We also speak to Chubuike Rotimi Amaechi, the governor of Rivers State in Nigeria - a country that has managed to contain the virus. And we report from Liberia, Senegal and Guinea about the human cost of the crisis. Also on Counting the Cost: Going supersonic. Swiss company Swiss Space System is trying to revive the idea of supersonic travel, and make it even faster.