Overview
Ebola virus disease is a severe illness caused by Ebola virus, one of a group of related viruses that fruit bats are thought to carry naturally. People catch it through direct contact with the blood or other body fluids of an infected person or animal, not through the air.
It matters that the illness is now treatable. WHO recommends two monoclonal antibody medicines alongside intensive supportive care, and two vaccines are approved. Both the medicines and the vaccines work against Ebola virus specifically, not against the related Sudan and Bundibugyo viruses.
Disease Summary
- Category
- Infectious Disease
- Cause
- Ebola virus
- Transmission
- Direct contact with the body fluids of a sick or dead person
- Body System
- Multiple organ systems
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Symptoms begin 2 to 21 days after exposure, on average 8 to 10 days. The illness starts with a dry phase of fever and aches, then moves into a wet phase about 4 to 5 days later.
Sudden Fever
Fever is usually the first symptom and appears with a general sense of being unwell.
Severe Headache
Headache is listed by both WHO and CDC among the first symptoms of the illness.
Muscle and Joint Pain
Aching muscles and joints are prominent in the early days and can be severe.
Weakness and Fatigue
Profound weakness is one of the defining features of the early illness.
Sore Throat and Loss of Appetite
Both are listed among the early symptoms before vomiting and diarrhoea begin.
Severe Watery Diarrhoea
CDC describes this as the start of the wet phase, about 4 to 5 days after symptoms begin. It causes very large fluid losses.
Vomiting and Abdominal Pain
Vomiting and stomach pain arrive with the diarrhoea and drive rapid dehydration.
Rash
CDC reports that a rash typically appears around days 5 to 7 of the illness.
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop.
Unexplained Bleeding
CDC reports unexplained bleeding in 40% of patients, seen as bruising, oozing from injection sites, bleeding gums, or blood in vomit or stool.
Severe Dehydration
Large-volume diarrhoea and vomiting cause dehydration that needs intravenous fluids, often in large amounts.
Confusion or Altered Awareness
CDC lists confusion among the features of the wet phase and it signals deterioration.
Difficulty Breathing or Chest Discomfort
Both are listed by CDC among wet-phase features and require urgent support.
Shock
CDC states that fatal cases die from multiple organ failure and septic shock, so collapse or a weak rapid pulse is an emergency.
Diagnosis
Exposure History
CDC advises contacting a doctor or health department immediately if you believe you were exposed to someone with Ebola disease and have symptoms. History drives suspicion, because the early symptoms are not specific.
The 21-Day Window
Symptoms may appear 2 to 21 days after contact, on average 8 to 10 days. WHO monitors contacts of cases for 21 days for this reason.
Recognising the Dry and Wet Phases
CDC separates an early dry phase of fever, aches and fatigue from a wet phase of diarrhoea, vomiting and abdominal pain about 4 to 5 days later. The distinction guides how much fluid a patient needs.
Excluding More Likely Causes
CDC states that timely identification of other, more likely infections through routine laboratory testing is essential. Malaria in particular must be tested for.
Immediate Isolation as Part of Assessment
CDC directs that a suspected patient is isolated in a single room straight away, with appropriate protective equipment and dedicated equipment.
Laboratory Tests
Malaria Test
Done in every febrile patient in an endemic area, because malaria is far more common, looks the same at first, and is rapidly treatable.
Reverse Transcriptase PCR
The test that confirms infection. CDC notes the virus is detectable only after symptoms begin, and it may take up to 3 days from symptom onset to reach detectable levels, so an early negative test may need repeating.
Antigen Detection Test
Detects viral protein during acute illness. WHO lists it among the diagnostic methods.
Antibody ELISA
Detects the antibodies the body produces. More useful later in the illness or in recovered patients than at first presentation.
Supporting Blood Tests
CDC describes a low white cell count, low platelets, raised liver enzymes, protein in the urine and prolonged clotting times. These guide supportive treatment.
Treatment
Optimised Supportive Care
WHO states that early intensive supportive care with rehydration and symptomatic treatment improves survival. Replacing the fluid lost through diarrhoea and vomiting is the single most important intervention.
Monoclonal Antibody Treatment
WHO recommends two monoclonal antibody medicines, ansuvimab and the three-antibody combination known as Inmazeb, for Ebola virus disease. Neither is approved for Sudan virus disease or Bundibugyo virus disease.
Blood Pressure and Oxygen Support
CDC clinical guidance includes maintaining blood pressure with medicines where needed and maintaining oxygen levels.
Symptom Control and Nutrition
WHO lists pain control, nutrition and the treatment of other infections present at the same time among the components of care.
Treatment of Co-Infections
CDC adds treatment of secondary bacterial infections and of existing health conditions to the standard of care.
Prevention
Vaccination in outbreak settings
WHO reports two approved vaccines against Ebola virus disease. CDC states the single-dose Ervebo vaccine is approved from 12 months of age and protects against Ebola virus only.
Avoid contact with the body fluids of a sick or dead person
This is the main route of person-to-person spread, and includes blood, vomit, diarrhoea, saliva, sweat, urine, breast milk, semen and vaginal fluid.
Safe and dignified burial
WHO lists this explicitly as a control measure, because traditional washing and preparation of the body has repeatedly driven outbreaks.
Avoid raw bushmeat and contact with bats and primates
WHO advises reducing the risk of contact with infected fruit bats, monkeys and apes, and avoiding consumption of their raw meat.
Contact tracing with 21 days of monitoring
WHO monitors the contacts of every case for 21 days, which matches the longest incubation period.
Precautions for survivors
WHO states the virus can persist in the testicles, eyes and brain, and recommends that male survivors have semen tested for up to 15 months, or practise safer sex for 12 months.
Risk Factors
Family Members and Carers
Most person-to-person transmission happens during care of a sick relative or preparation of a body.
- Anyone nursing a sick person at home without protective equipment
- People handling soiled bedding, clothing or surfaces
- Family members washing or preparing a body for burial
- Children cared for by an infected parent
Health Workers and Laboratory Staff
Care given before Ebola is suspected carries the highest risk.
- Staff treating a patient before isolation begins
- Facilities without reliable protective equipment
- Laboratory staff handling untreated samples
- Anyone performing procedures that produce splashes or spills
Survivors and Their Partners
WHO states the virus can persist in sites the immune system does not fully reach.
- Male survivors, in whom sexual transmission has been documented up to 15 months after recovery
- Sexual partners of recent survivors
- Survivors with eye symptoms, since the virus can persist in the eye
- Mothers who are breastfeeding after recovery
Complications
Multiple Organ Failure and Septic Shock
CDC states that fatal cases develop severe signs early and die from organ failure and septic shock.
Bleeding and Clotting Failure
CDC reports unexplained bleeding in 40% of patients, with prolonged clotting times.
Kidney and Liver Injury
WHO lists kidney and liver impairment among the later features of the illness.
Severe Dehydration and Salt Loss
Large-volume diarrhoea and vomiting deplete the body of fluid and salts, which is what intensive supportive care corrects.
Long-Term Problems in Survivors
CDC lists tiredness, headache, muscle and joint pain, vision and hearing problems, memory difficulty, depression, anxiety and post-traumatic stress among the problems survivors report.
Persistence of the Virus After Recovery
WHO states the virus can persist in the testicles, eyes and brain, with sexual transmission documented up to 15 months after clinical recovery.
When to Seek Medical Care
Any Symptoms After a Known Exposure
CDC advises contacting a doctor or health department immediately if you believe you were exposed and have symptoms.
Fever Within 21 Days of Leaving an Outbreak Area
The incubation period is 2 to 21 days, so fever inside that window after possible exposure needs urgent assessment.
The Start of Diarrhoea and Vomiting
This marks the wet phase, when fluid loss and deterioration happen fastest.
Any Unexplained Bleeding
Bleeding from the gums, nose, injection sites or in vomit or stool is an emergency.
Call Ahead Rather Than Arriving Unannounced
This allows isolation and protective equipment to be arranged before you arrive.
Prognosis
Case Fatality Averages Around 50%
WHO reports an average of around 50%, with a range of 25% to 90% across past outbreaks. The figure varies with how early people reach care.
Early Fluid Replacement Improves Survival
WHO states that early intensive supportive care with rehydration and symptomatic treatment improves the chance of survival.
Recovery Begins Around Day Six
CDC notes that survivors may have fever for several days and begin improving about 6 days after symptoms started, while fatal cases typically die between days 6 and 16.
Survivors Often Have Lasting Symptoms
CDC states that the timing, severity and duration of problems in survivors vary widely, and that follow-up care is needed.
Differential Diagnosis
Malaria
The most important alternative. It shares the early fever and aches and must be tested for in every case, because it is common and rapidly treatable.
Typhoid Fever
Causes prolonged fever and abdominal symptoms, and is separated by blood culture.
Meningococcal Infection
Also causes fever with a rash of small bleeding spots and shock, and is separated by blood culture and examination of spinal fluid.
Pneumonia
Focal chest findings and imaging point away from Ebola, which begins with systemic symptoms rather than chest signs.
Lassa Fever and Other Viral Haemorrhagic Fevers
Clinically very similar. The distinction matters because vaccines and specific medicines exist only for some of them, and it requires laboratory testing.
References
World Health Organization: Ebola disease
WHO fact sheet on the Ebola disease group, transmission, treatment, vaccines and outbreak control.
CDC: Ebola Disease Basics
Overview of transmission, symptoms, incubation and who is at risk.
CDC: Clinical Features of Ebola Disease
The dry and wet phases, laboratory findings and complications.
CDC: History of Ebola Outbreaks
Case counts and case fatality figures for past and current outbreaks.
Frequently Asked Questions
How soon after exposure would someone become ill?
CDC states symptoms may appear 2 to 21 days after contact with the virus, and that on average people begin showing symptoms 8 to 10 days after exposure. WHO gives the same range, which is why contacts are monitored for 21 days.
Can someone spread Ebola before they have symptoms?
No. CDC states that a person is only contagious once they begin showing symptoms. Spread then occurs through direct contact with body fluids such as blood, vomit, diarrhoea, saliva, sweat, urine, breast milk and semen.
Is there a cure?
For Ebola virus disease, WHO recommends two monoclonal antibody treatments given alongside optimised supportive care. WHO states there are no approved treatments for the related Sudan virus disease or Bundibugyo virus disease.
Is there a vaccine, and does it cover every type?
Two vaccines are approved against Ebola virus disease. CDC states that the Ervebo vaccine is given as a single dose from 12 months of age and protects only against Ebola virus, not against the other related viruses. Candidate vaccines for those are at different stages of development.
Can a survivor still pass Ebola on?
In specific ways, yes. WHO states the virus can persist in the testicles, eyes and brain, and that sexual transmission has been documented up to 15 months after recovery. WHO recommends that male survivors have semen tested for up to 15 months or practise safer sex for 12 months.