Ebola glossary

Short explanations of the key terms around Ebola and outbreaks.

CFR (case fatality rate)

The share of confirmed patients who die. For Ebola it averages around 50%, depending heavily on strain and care.

Confirmed case

A patient in whom the virus has been detected by a laboratory test (usually PCR).

Contact tracing

Finding and monitoring for 21 days everyone who had contact with a patient.

End of outbreak

Declared after 42 days (twice the maximum incubation period) without new cases.

Ervebo (rVSV-ZEBOV)

Approved vaccine against the Zaire strain. Does not protect against Sudan or Bundibugyo virus.

Filovirus

Family of thread-shaped viruses that includes Ebola and Marburg viruses.

Imported case

A patient infected abroad who then travelled or was transferred into the country.

Incubation period

Time between infection and first symptoms: 2 to 21 days, usually 8 to 10.

Index case

The first known patient in an outbreak.

Isolation / quarantine

Isolation separates the sick; quarantine restricts healthy people who may have been exposed.

Monoclonal antibodies

Treatments such as Inmazeb and Ebanga that markedly reduce mortality from the Zaire strain.

Orthoebolavirus

The genus containing the six known Ebola species, including Zaire, Sudan and Bundibugyo.

PCR test

Lab test detecting the virus's genetic material; the standard for diagnosis.

PHEIC

Public Health Emergency of International Concern, declared by the WHO.

PPE

Personal protective equipment: suit, gloves, mask and goggles for health workers.

Probable case

A person (often deceased) with a strong epidemiological link who can no longer be tested.

Reservoir host

The animal in which the virus circulates without causing illness; for Ebola most likely fruit bats.

Ring vaccination

Vaccinating contacts and contacts-of-contacts around a patient to form a 'ring' of immunity.

Suspected case

Someone with matching symptoms and possible exposure, not yet tested. Many suspected cases turn out negative.

Viral haemorrhagic fever

Umbrella term for viral diseases that can cause bleeding, such as Ebola, Marburg and Lassa.

Zoonosis / spillover

Transmission of a disease from animals to humans. For Ebola probably via bats or infected bushmeat.