Spillover: Zika, Ebola & Beyond

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The viral envelope (gray) and viral proteins (red) involved in binding to and entering host cells are shown. The helical core is not visible.

Ebola Cross Section

A. Glycoprotein; B. Lipid envelope; C. Matrix protein; D. RNA genome; E. Nucleocapsid proteins; F. Polymerase

Ebola Virus

  • Filoviridae family, which also includes Marburg virus
  • ~80-nm × 800-nm enveloped particles with a helical core
  • Linear, ss – RNA genome of ~19,000 bp
  • Infects humans, other primates, and bats
  • Vaccines are currently being tested

Show Relative Size

Ebola virus and its relative Marburg virus are perhaps best known for the gruesome clinical manifestations and high fatality rates they cause in humans. Outbreaks of Ebola virus infection are known to have occurred in Africa as early as 1976, but until 2014 they were short-lived and isolated to relatively small groups of people. The outbreak in West Africa in 2014 spread primarily across Sierra Leone, Guinea, and Liberia, killing more than 11,000 people over the course of two years. During this time, limited virus spread also occurred in several other countries, but was quickly controlled. Ebola virus is zoonotic, which means it can be transmitted to humans from infected animals. Bats are known to carry Ebola virus, and the transmission of the virus from wild bat populations to humans is referred to as a spillover event.

Historical Timeline of Ebola Virus Outbreaks

world map

Ebola virus year of first appearance

  1. 1976
  2. 1994
  3. 1996
  4. 2000
  5. 2001
  6. 2014

Relative Sizes

Chart showing size comparison of different viruses.

The white line represents 100 nanometers (nm). For comparison, the width of a human hair is about 75,000 nm, so it would be 750 times as long!