Ebola virus disease (EVD) is a deadly disease with occasional outbreaks that occur primarily on the African continent. EVD most commonly affects people and nonhuman primates (such as monkeys, gorillas, and chimpanzees). It is caused by an infection with a group of viruses within the genus Ebolavirus:
Ebola virus (species Zaire ebolavirus)
Sudan virus (species Sudan ebolavirus)
Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus)
Bundibugyo virus (species Bundibugyo ebolavirus)
Reston virus (species Reston ebolavirus)
Bombali virus (species Bombali ebolavirus)
Of these, only four (Ebola, Sudan, Taï Forest, and Bundibugyo viruses) are known to cause disease in people. Reston virus is known to cause disease in nonhuman primates and pigs, but not in people. It is unknown if Bombali virus, which was recently identified in bats, causes disease in either animals or people.
Ebola virus was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of Congo. Since then, the virus has been infecting people from time to time, leading to outbreaks in several African countries. Scientists do not know where Ebola virus comes from. However, based on the nature of similar viruses, they believe the virus is animal-borne, with bats or nonhuman primates with bats or nonhuman primates (chimpanzees, apes, monkeys, etc.) being the most likely source. Infected animals carrying the virus can transmit it to other animals, like apes, monkeys, duikers and humans.
The virus spreads to people initially through direct contact with the blood, body fluids and tissues of animals. Ebola virus then spreads to other people through direct contact with body fluids of a person who is sick with or has died from EVD. This can occur when a person touches these infected body fluids (or objects that are contaminated with them), and the virus gets in through broken skin or mucous membranes in the eyes, nose, or mouth. People can get the virus through sexual contact with someone who is sick with EVD, and also after recovery from EVD. The virus can persist in certain body fluids, like semen, after recovery from the illness.
Ebola survivors may experience side effects after their recovery, such as tiredness, muscle aches, eye and vision problems and stomach pain.