joanna blundell explains. >> reporter: ebola has returned to liberia.ths after it was declared officially free of the virus 18 age boy has died. >> the sample was taken from a 17-year-old dead body from. [ inaudible ] >> reporter: it's devastating news for a country which has already suffered taj ill losses, 4,800 have died from the virus nearly half all those killed as ebola is swept across less africa last from. no one knows how this young boy con tranlted the illness or who he has been in contact with. there is another mystery how the virus got there. it is a rural part of the country over 100-kilometers from sierra leone and guinea, both of which have seen cases of ebola rise in recent week but borders are staying open. >> border closure is not an option. we have the borders protected very well. we have the. [ inaudible ] going on there. we have not established whether or not this case came from any country across the border. >> reporter: and that policy is angering some people. >> i feel very disappointment about the government. if you look at the