Ebola is a deadly virus originating in parts of Africa. It is classified as a hemorrhagic fever, putting it in the same category as Marburg fever, Lassa fever, and Dengue fever. There are four varieties of Ebola, named after their country of origin. Ebola Zaire, Ebola Cote d'Ivoire, and Ebola Sudan are all known to cause serious illness in human beings. Ebola Reston does not appear to cause illness in people.

Ebola may be transmitted via bodily fluids such as blood and secretions. Well-established vectors for infection include handling other primates infected with Ebola, contact with infected corpses during funeral services, and touching infected patients without exercising proper caution. It is thought that the disease may be transferred through airborne particles, but so far there are no proven cases of this method of infection. Hospital staff are particularly susceptible to infection during an outbreak, particularly in the nations in which Ebola has so far occurred. Difficult economic conditions and a lack of access to proper sterilization and protective garments make nurses and doctors an easy target when they deal with patients who have been infected with Ebola.

Contrary to popular misconception, Ebola does not kill within a matter of hours, and the virus will incubate for up to two weeks before symptoms begin to occur. These symptoms include a rapidly intensifying fever, horrible muscle pain, and debilitating weakness. Further symptoms may include diarrhea and vomiting, as well as both internal and external bleeding.

While popular media has presented the symptoms of Ebola as fast-acting and truly horrific visually, in most cases there is little external exhibition of the virus. While external bleeding may occur on occasion, it is rare, and the popular image of people "melting" or of internal organs literally liquefying is blown out of proportion. In fact, although Ebola is classified as a hemorrhagic fever, less than half of cases ultimately result in hemorrhaging. When hemorrhaging does occur, however, it is certainly capable of some grotesque exhibitions, with bleeding possibly occurring from the mouth, genitals, nose, and beneath the skin.

The first outbreak of Ebola in which the virus was identified occurred in western Sudan and part of Zaire, now known as the Democratic Republic of Congo, in 1976. More than 600 people were infected, of which more than 400 died. In 1995, a second large outbreak occurred in the Democratic Republic of Congo, infecting 315 people and killing 250. Since first being identified, more than 1800 cases of Ebola have been determined, of which 1200 resulted in deaths, making it one of the most fatal viruses to affect humans.

There have been reports that ingesting an extract from a West African fruit helps to treat Ebola once it has been contracted; these reports have yet to be rigorously tested, however. Work on an Ebola vaccine is ongoing, with the recent success of a totally reliable vaccine for Ebola in monkeys. Though no human vaccine has been produced that yields positive results, the future is promising.