By Josephus Olu-Mammah and Umaru Fofana FREETOWN (Reuters) - The worst ever Ebola outbreak is causing enormous damage to West African economies as foreign businessmen quit the region, the African Development Bank said, while a leading medical charity branded the international response "entirely inadequate." As transport companies suspend services, cutting off the region, governments and economists have warned that the epidemic could crush the fragile economic gains made in Sierra Leone and Liberia following a decade of civil war in the 1990s. At least 1,427 people have died of the deadly hemorrhagic virus since it was first detected in the remote jungles of southeast Guinea in March and spread quickly to neighbouring Liberia and Sierra Leone. Five people have also died in Nigeria. Air France, the French network of Air France-KLM said on Wednesday it had suspended flights to Sierra Leone after advice from the French government.