The Ebola disease causes a high fever and internal and external bleeding. There is no cure and no vaccine and it has a high fatality rate.
In a statement on its website today, the UN health agency said at least 230 suspected or confirmed cases of Ebola have been recorded so far in Guinea and Liberia. Most of the cases are in Guinea.
The statement said 129 deaths in Guinea and 13 in Liberia have been linked to the disease.
The outbreak is highly unusual as the disease is typically found in central or eastern Africa.