WHO updates fact sheet on Ebola virus disease (13 May 2017)

The World Health Organization (WHO) has updated its fact sheet on Ebola virus disease.

Background information:

The Ebola virus causes an acute, serious illness which is often fatal if untreated.

Ebola virus disease (EVD) first appeared in 1976 in 2 simultaneous outbreaks, one in what is now, Nzara, South Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name.

Key Messages:

Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans.

Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest.

Ebola then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.

Burial ceremonies that involve direct contact with the body of the deceased can also contribute in the transmission of Ebola.

People remain infectious as long as their blood contains the virus.

WHO recommends that:

  • All Ebola survivors and their sexual partners should receive counselling to ensure safe sexual practices until their semen has twice tested negative. Survivors should be provided with condoms.
  • Male Ebola survivors should be offered semen testing at 3 months after onset of disease, and then, for those who test positive, every month thereafter until their semen tests negative for virus twice by RT-PCR, with an interval of one week between tests.
  • Ebola survivors and their sexual partners should either:
    • abstain from all types of sex, or
    • observe safe sex through correct and consistent condom use until their semen has twice tested negative.
  • Having tested negative, survivors can safely resume normal sexual practices without fear of Ebola virus transmission.
  • Based on further analysis of ongoing research and consideration by the WHO Advisory Group on the Ebola Virus Disease Response, WHO recommends that male survivors of Ebola virus disease practice safe sex and hygiene for 12 months from onset of symptoms or until their semen tests negative twice for Ebola virus.
  • Until such time as their semen has twice tested negative for Ebola, survivors should practice good hand and personal hygiene by immediately and thoroughly washing with soap and water after any physical contact with semen, including after masturbation. During this period used condoms should be handled safely, and safely disposed of, so as to prevent contact with seminal fluids.

The incubation period is 2 to 21 days.

Humans are not infectious until they develop symptoms.

First symptoms are the sudden onset of fever fatigue, muscle pain, headache and sore throat. This is followed by

  • vomiting,
  • diarrhoea,
  • rash,
  • symptoms of impaired kidney and liver function, and in some cases,
  • both internal and external bleeding (e.g. oozing from the gums, blood in the stools).

Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.

Studies of viral persistence indicate that in a small percentage of survivors, some body fluids may test positive on reverse transcriptase polymerase chain reaction (RT-PCR) for Ebola virus for longer than 9 months.

It can be difficult to clinically distinguish EVD from other infectious diseases such as malaria, typhoid fever and meningitis. Confirmation that symptoms are caused by Ebola virus infection are made using the following diagnostic methods:

  • antibody-capture enzyme-linked immunosorbent assay (ELISA)
  • antigen-capture detection tests
  • serum neutralization test
  • reverse transcriptase polymerase chain reaction (RT-PCR) assay
  • electron microscopy
  • virus isolation by cell culture.

The average EVD case fatality rate is around 50%. Case fatality rates have varied from 25% to 90% in past outbreaks.

Supportive care-rehydration with oral or intravenous fluids- and treatment of specific symptoms, improves survival. There is as yet no proven treatment available for EVD.

Community engagement is key to successfully controlling outbreaks.

Good outbreak control relies on applying a package of interventions, namely

  • case management,
  • infection prevention and control practices,
  • surveillance and contact tracing,
  • a good laboratory service,
  • safe burials and
  • social mobilisation.

Health-care workers should always take standard precautions when caring for patients, regardless of their presumed diagnosis. These include

  • basic hand hygiene,
  • respiratory hygiene,
  • use of personal protective equipment (to block splashes or other contact with infected materials),
  • safe injection practices and
  • safe burial practices.

Health-care workers caring for patients with suspected or confirmed Ebola virus should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding.

When in close contact (within 1 metre) of patients with EBV, health-care workers should wear

  • face protection (a face shield or a medical mask and goggles),
  • a clean, non-sterile long-sleeved gown, and
  • gloves (sterile gloves for some procedures).

Useful Links:

Link to the updated fact sheet:


Link to WHO page on Ebola diagnostics:


Link to WHO document ‘Clinical care for survivors of Ebola virus disease’:

Click to access WHO_EVD_OHE_PED_16.1_eng.pdf

Link to WHO page on Frequently asked questions on Ebola virus disease:


Link to WHO page containing publications for Ebola case management, infection prevention and control:


Link to WHO document ‘infection prevention and control guidance for care of patients in health care settings’, with focus on Ebola:


Link to WHO document on Ebola and Marburg virus disease epidemics: preparedness, alert, control and evaluation:




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