Ebola is short for ebola hemorrhagic fever, which is caused by a virus named after a river in the Congo, where it was first discovered in 1976. The virus has four known variations and three of them are known to cause the disease in humans. The last variation has only caused the fever in primates. Researchers have theorized that the virus is borne only to primates native to Africa, making it hard for the virus to cause epidemics elsewhere. As yet, individuals outside of Africa have only become infected with the disease after research accidents.

Outbreaks of Ebola are typically sporadic and quickly form epidemics within the clinical setting. However, no severe epidemics have ever occurred. In total, only slightly more than one thousand recorded deaths occurred as a result of the Ebola virus. Researchers believe that outbreaks occur when a human comes into contact with an animal infected with the virus. The virus is then able to spread by contact with infected blood or other secretions, whether it is directly or indirectly with needles and other objects. Although it has been shown that the virus can spread through the air, a human infection by aerosol transmission has never been recorded.

The Ebola virus has an incubation time of two to twenty-one days. The first symptoms include fevers, headaches, aching, soreness of the throat, diarrhea, vomiting, and stomach pains. Other symptoms such as rashes, hiccups, bloodshot eyes, and external bleeding have also occurred in humans. Ebola also makes it difficult for the blood to clot, causing wounds that open on the skin to bleed continuously. It is very difficult to diagnose Ebola in its early stages because the symptoms are common with a number of other ailments.

There is no cure for Ebola infections, although the victims can be supported, and the vast majority (~90%) of infected patients die. When outbreaks occur, quarantines are immediately established to stop spread of the virus. Government agencies have take great care to prevent serious epidemics and spreading of the virus to other continents.

The virus itself is a filovirus, which is shaped like a long string. The virus takes about 8 hours to reproduce and can produce hundreds of thousands of replicants in a period of several hours.