The most widespread epidemic of Ebola virus disease (commonly known as "Ebola") in history is currently ongoing in several West African countries.
It has caused significant mortality, with a reported case fatality rate of 70%. Ebola virus disease was first described in 1976 in two simultaneous outbreaks in sub-Saharan Africa; this is the 26th outbreak and the first to occur in West Africa.
It began in Guinea in December 2013 and then spread to Liberia and Sierra Leone. A small outbreak of twenty cases occurred in Nigeria and one case occurred in Senegal, both now declared disease-free. Several cases have been reported in Mali, and an isolated case has been reported in the United Kingdom.
Imported cases in the United States and Spain have led to secondary infections of medical workers but have not spread further.
As of 3 January 2015, the World Health Organization (WHO) and respective governments have reported a total of 21,206 suspected cases and 8,386 deaths, though the WHO believes that this substantially understates the magnitude of the outbreak.