An epidemic of Ebola virus disease (EVD) is ongoing. It began in Guinea in December 2013 then spread to Liberia and Sierra Leone. A few much smaller subsidiary outbreaks have occurred elsewhere, with outbreaks in Nigeria and Senegal that appear to have been successfully contained, and secondary infections of medical workers with very low case numbers in the United States and Spain, neither of which is yet showing any signs of spreading in the general population. As of October 2014, the World Health Organization (WHO), the United States Centers for Disease Control and Prevention (CDC) and local governments reported a total of 8,400 suspected cases and 4,033 deaths (4,633 cases and 2,423 deaths having been laboratory confirmed), though the WHO believes that this substantially understates the magnitude of the outbreak with possibly 2.5 times as many cases as have been reported. On 14 October, during a news conference in Geneva, the assistant director-general of the WHO stated that there could be as many as 10,000 new Ebola cases per week by December 2014.

The current epidemic of EVD, caused by Ebola virus, is the most severe outbreak of Ebola since the finding of ebolaviruses in 1976, and by September 2014 cases of EVD from this single outbreak exceeded the sum of all previously identified cases.The epidemic has caused significant mortality, with a Case Fatality Rate (CFR) reported as 71%

Affected countries have encountered many difficulties in their control efforts. The WHO has estimated that region's capacity for treating EVD is insufficient by the equivalent of 2,122 beds as of September 24th. In some areas, people have become suspicious of both the government and hospitals; some hospitals have been attacked by angry protestors who believe that the disease is a hoax or that the hospitals are responsible for the disease. Many of the areas that are seriously affected with the outbreak are areas of extreme poverty with limited access to soap or running water to help control the spread of disease. Other factors include reliance on traditional medicine, and cultural practices that involve physical contact with the deceased, especially death customs such as washing the body of the deceased Some hospitals lack basic supplies and are understaffed. This has increased the chance of staff catching the virus themselves. In August, the WHO reported that ten percent of the dead have been health care workers.

By the end of August, the WHO reported that the loss of so many health workers was making it difficult for them to provide sufficient numbers of foreign medical staff. By September 2014, Médecins Sans Frontières/Doctors Without Borders (MSF), the largest NGO working in the affected regions, had grown increasingly critical of the international response. Speaking on 3 September, the international president spoke out concerning the lack of assistance from the United Nations member countries saying, "Six months into the worst Ebola epidemic in history, the world is losing the battle to contain it." A United Nations spokesperson stated "they could stop the Ebola outbreak in West Africa in 6 to 9 months, but only if a 'massive' global response is implemented."The Director-General of the WHO, Margaret Chan, called the outbreak "the largest, most complex and most severe we've ever seen" and said that it "is racing ahead of control efforts".In a 26 September statement, the WHO said, "The Ebola epidemic ravaging parts of West Africa is the most severe acute public health emergency seen in modern times.