The most widespread epidemic of Ebola virus disease (commonly known as "Ebola") in history is currently ongoing in three West African countries.[11] It has caused significant mortality, with reported case fatality rates of up to 70%[12][13][14][note 1] and specifically 57–59% among hospitalized patients.[15] 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. The outbreak began in Guinea in December 2013 and then spread to Liberia and Sierra Leone.[12] A small outbreak of twenty cases occurred in Nigeria and one case occurred in Senegal.[16] Several cases were reported in Mali,[4][17] and an isolated case occurred in the United Kingdom and another in Sardinia.[14] Imported cases in the United States and Spain led to secondary infections of medical workers but did not spread further.[18][19] Liberia was officially declared Ebola-free on 9 May after 42 days without any further cases being recorded, however new cases were reported in late June and early July. As of 11 August 2015[update], the World Health Organization (WHO) and respective governments have reported a total of 27,984 suspected cases and 11,298 deaths,[2] though the WHO believes that this substantially understates the magnitude of the outbreak.[20][21]