In 2014, the World Health Organization (WHO) reported that largest outbreak of Ebola in history had occurred, and the first in West Africa. It affected four countries in West Africa: Guinea, Liberia, Nigeria, and Sierra Leone and killed more than 11,000 people.

Over the course of the epidemic, the disease spread to 7 additional countries: Italy, Mali, Nigeria, Senegal, Spain, the United Kingdom, and the United States (U.S.). Secondary infections occurred in Italy, Mali, Nigeria and U.S. In June 2016, the outbreak was declared over. More than 28 600 people had been infected and 11,325 people had died.