The West African Ebola virus epidemic of 2013 to 2016 was the most widespread epidemic of Ebola virus disease in history. The disease caused significant loss of life and social disruption, mainly in three West African countries. The outbreak began in Guinea in December 2013 and then spread to Liberia and Sierra Leone, with minor outbreaks elsewhere. It caused significant mortality, with reported case fatality rates of up to 70% and specifically 57–59% among hospitalized patients. Small outbreaks occurred in Nigeria and Mali, and isolated cases occurred in Senegal, the United Kingdom and Sardinia. Imported cases in the United States and Spain led to secondary infections of medical workers but did not spread further. As of 8 May 2016, the World Health Organization and respective governments have reported a total of 28,657 suspected cases and 11,325 deaths (39.5%), though the WHO believes that this substantially understates the magnitude of the outbreak.
On 28 March 2016, the Director-General of WHO terminated the Public Health Emergency of International Concern status of the Ebola outbreak. Although the epidemic is no longer out of control, flare-ups of the disease are likely to continue for some time.
The outbreak resulted in 17,000 survivors of the disease, many of whom report post recovery symptoms termed Post-Ebola Syndrome, with symptoms so severe that they may require medical care for months and even years. Also of concern is the apparent ability of the virus to "hide" in the recovered survivor's body for an extended period of time and become active or infect a sexual partner for months or years following recovery from the acute episode of illness.