Ebola virus disease: transmission, symptoms, vaccines and treatment

Discovery and outbreaks

Ebola virus disease was first reported in 1976 in what is now the Democratic Republic of the Congo, near the Ebola River, from which the disease takes its name. Case fatality has ranged from 25% to 90% in past outbreaks, depending on the virus species, the outbreak setting and access to care. Fruit bats are considered the likely natural host.

The 2014–2016 West African epidemic

The West African epidemic was the largest Ebola outbreak since the virus was discovered and the direct background of the 2016 Berlin workshop. It started in Guinea and spread to Sierra Leone and Liberia, with cases in seven further countries.

How Ebola spreads

Ebola spreads through direct contact – via broken skin or mucous membranes – with the blood, secretions or other body fluids of infected people, and with objects contaminated by them. Caring for patients without protection and unsafe burial practices drove much of the transmission in West Africa. People are not considered infectious before symptoms appear.

The virus can persist in immune-privileged sites, such as semen, in some survivors. Transmission from persistently infected survivors was documented after the West African epidemic. More on this on the page survivors and long-term effects.

Symptoms and incubation

The time from infection to symptom onset is 2 to 21 days. Illness begins with fever, fatigue, muscle pain, headache and sore throat, followed by vomiting, diarrhoea, rash and signs of impaired kidney and liver function. Some patients develop internal and external bleeding. Differential diagnoses include malaria, typhoid fever, Lassa fever and Marburg virus disease, so confirmation requires laboratory testing.

Ebola vaccines

The rVSVΔG-ZEBOV-GP vaccine, marketed as Ervebo, was approved by the European Medicines Agency and the US FDA in December 2019. It is a live, attenuated, recombinant vesicular stomatitis virus carrying only the Ebola glycoprotein gene, so it contains no live Ebola virus. It protects against Zaire ebolavirus, not against Sudan virus or Marburg virus, and is given as a single dose.

A second regimen, Ad26.ZEBOV followed by MVA-BN-Filo (Zabdeno/Mvabea), is given in two doses. Field evidence supports vaccination even in breakthrough cases: in a retrospective analysis of 2,279 confirmed patients in the Democratic Republic of the Congo (2018–2020), case fatality was 25% among vaccinated patients versus 56% among unvaccinated patients.

Treatment

Early supportive care – rehydration and treatment of specific symptoms – improves survival. For Ebola caused by Zaire ebolavirus, two monoclonal antibody treatments are available: Inmazeb (atoltivimab, maftivimab and odesivimab) and ansuvimab (Ebanga). A randomised controlled trial reported reduced disease severity with monoclonal antibody therapy. These products do not cover other Ebola species.

Frequently asked questions