The 2013–2016 epidemic of Ebola virus disease, centered in Western Africa, was the most widespread outbreak of the disease in history. It caused major loss of life and socioeconomic disruption in the region, mainly in Guinea, Liberia and Sierra Leone. The first cases were recorded in Guinea in December 2013; later, the disease spread to neighbouring Liberia and Sierra Leone, with minor outbreaks occurring in Nigeria and Mali. Secondary infections of medical workers occurred in the United States and Spain. In addition, isolated cases were recorded in Senegal, the United Kingdom and Italy. The number of cases peaked in October 2014 and then began to decline gradually, following the commitment of substantial international resources.

An epidemic is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infections, an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered an epidemic.