STRAINS OF EBOLA

There are currently five known varieties (also known as “strains”) of the Ebola virus: Taï Forest, Sudan, Bundibugyo, Zaire, and Reston. All, with the exception of Reston, have been identified in humans.

TAÏ FOREST

Taï Forest (TAFV) virus was first identified as a new “strain” of Ebola virus in 1995 and has only had one known occurrence among humans, though it devastated the western chimpanzee population in Taï National Park, Côte d’Ivoire. While it is not known how TAFV infected these chimpanzees, bats are suspected.

SUDAN

This was identified in 1998 as Sudan Ebola virus and is endemic (a constant presence) in Sudan and Uganda.

BUNDIBUGYO

Bundibugyo (BDBV) was first discovered in August 2007 when an outbreak occurred in the Bundibugyo township in western Uganda. Blood samples sent to the US Centers for Disease Control and Prevention determined that this was a new variety. Another outbreak in 2007 was also confirmed to be BDBV.

ZAIRE

Zaire is the most lethal of all Ebola strains. Endemic in Central Africa since 1976, it is the strain of the virus that is of the most concern throughout the world. It is thought to be the strain that has caused the current 2014 outbreak in West Africa.

RESTON

Reston virus (RESTV), named for Reston, Virginia, where the strain was first isolated in 1990, is a mutation from the Ebola virus discovered in a species of monkey imported from the Philippines. Reston virus is lethal to animals but has not, as yet, affected humans.

TIP

A special protein has been found to be essential both to the entry of Ebola and its replication. In laboratory tests, human cells that didn’t have this transporter appeared impervious to Ebola when exposed. This suggests that some humans could be naturally resistant to the virus.