Colorized transmission electron micrograph (TEM) of EBOV. Image courtesy of the CDC.
The Ebola virus (member of the filoviruses) was first discovered in 1976, following concurrent outbreaks in the Sudan and Zaire (now Democratic Republic of Congo). Previously, the only known member of the filovirus group was the Marburg virus, discovered in 1967 in Marburg, Germany. The source of the Marburg virus was the African green monkey. The Zaire ebolavirus species, now referred to as Ebola virus (EBOV), and Sudan virus (SUDV) were the first two Ebola species identified.
A third Ebola species was identified in 1994, this time in Côte d'Ivoire, also known as Ivory Coast, in West Africa. One of three research workers who performed a necropsy on a wild chimpanzee with signs of hemorrhage became ill. The female research worker recovered and the new subtype of Ebola, named Cote d'Ivoire ebolavirus, was discovered in her blood. In 2010, the name was changed to Taï Forest ebolavirus (TAFV).
The fourth strain was discovered in monkeys, imported from the Philippines, living in an animal holding facility in Reston, Virginia. The Reston virus (RESTV) is not known to cause disease in humans, but does cause asymptomatic infections.
The Bundibugyo virus (BDBV) was isolated in 2007 by the Centers for Disease Control and Prevention (CDC), following an outbreak that started in the Bundibugyo district in western Uganda.