Ebola Hemorrhagic Fever (EHF)

What Is It?

Ebola hemorrhagic fever (EHF), also known as Ebola virus disease (EVD) or simply Ebola, is a viral hemorrhagic fever of humans and other primates caused by ebolaviruses.

The virus spreads through direct contact with body fluids, such as blood from infected humans or other animals. Spread may also occur from contact with items recently contaminated with bodily fluids. Spread of the disease through the air between primates, including humans, has not been documented in either laboratory or natural conditions. Semen or breast milk of a person after recovery from Ebola may carry the virus for several weeks to months.

Fruit bats are believed to be the normal carrier in nature, able to spread the virus without being affected by it. Other diseases such as malaria, cholera, typhoid fever, meningitis and other viral hemorrhagic fevers may resemble Ebola. Blood samples are tested for viral RNA, viral antibodies or for the virus itself to confirm the diagnosis.

The disease was first identified in 1976, in two simultaneous outbreaks: one in Nzara (a town in South Sudan) and the other in Yambuku (Democratic Republic of the Congo), a village near the Ebola River from which the disease takes its name. Ebola outbreaks occur intermittently in tropical regions of sub-Saharan Africa. Between 1976 and 2013, the World Health Organization reports 24 outbreaks involving 2,387 cases with 1,590 deaths. The largest outbreak to date was the epidemic in West Africa, which occurred from December 2013, to January 2016, with 28,646 cases and 11,323 deaths. It was declared no longer an emergency on 29 March 2016. Other outbreaks in Africa began in the Democratic Republic of the Congo in May 2017, and 2018. In July 2019, the World Health Organization declared the Congo Ebola outbreak a world health emergency.


It is believed that between people, Ebola spreads only by direct contact with the blood or other body fluids of a person who has developed symptoms of the disease. Body fluids that may contain Ebola viruses include saliva, mucus, vomit, faeces, sweat, tears, breast milk, urine and semen. The WHO states that only people who are very sick are able to spread Ebola disease in saliva, and whole virus has not been reported to be transmitted through sweat. Most people spread the virus through blood, faeces and vomit. Entry points for the virus include the nose, mouth, eyes, open wounds, cuts and abrasions. Ebola may be spread through large droplets; however, this is believed to occur only when a person is very sick. This contamination can happen if a person is splashed with droplets. Contact with surfaces or objects contaminated by the virus, particularly needles and syringes, may also transmit the infection. The virus is able to survive on objects for a few hours in a dried state, and can survive for a few days within body fluids outside of a person.

The Ebola virus may be able to persist for more than 3 months in the semen after recovery, which could lead to infections via sexual intercourse. Virus persistence in semen for over a year has been recorded in a national screening programme. Ebola may also occur in the breast milk of women after recovery, and it is not known when it is safe to breastfeed again. The virus was also found in the eye of one patient in 2014, two months after it was cleared from his blood. Otherwise, people who have recovered are not infectious.

The potential for widespread infections in countries with medical systems capable of observing correct medical isolation procedures is considered low. Usually when someone has symptoms of the disease, they are unable to travel without assistance.

Dead bodies remain infectious. Therefore, people handling human remains in practices such as traditional burial rituals or more modern processes such as embalming are at risk.


The length of time between exposure to the virus and the development of symptoms (incubation period) is between 2 and 21 days, and usually between 4 and 10 days. However, recent estimates based on mathematical models predict that around 5% of cases may take greater than 21 days to develop.

Symptoms usually begin with a sudden influenza-like stage characterised by feeling tired, fever, weakness, decreased appetite, muscular pain, joint pain, headache, and sore throat. The fever is usually higher than 38.3 °C (101 °F). This is often followed by nausea, vomiting, diarrhoea, abdominal pain, and sometimes hiccups. The combination of severe vomiting and diarrhoea often leads to severe dehydration. Next, shortness of breath and chest pain may occur, along with swelling, headaches, and confusion. In about half of the cases, the skin may develop a maculopapular rash, similar in appearance to measles. A flat red area covered with small bumps, five to seven days after symptoms begin.

In some cases, internal and external bleeding may occur. This typically begins five to seven days after the first symptoms. All infected people show some decreased blood clotting. Bleeding from mucous membranes or from sites of needle punctures has been reported in 40–50% of cases. This may cause vomiting blood, coughing up of blood, or blood in stool. Bleeding into the skin may create petechiae, purpura, ecchymoses or hematomas (especially around needle injection sites). Bleeding into the whites of the eyes may also occur. Heavy bleeding is uncommon; if it occurs, it is usually in the gastrointestinal tract. The incidence of bleeding into the gastrointestinal tract has decreased since early epidemics and is estimated to be approximately 10% with improved prevention of disseminated intravascular coagulation.


While there is no approved treatment for Ebola as of 2019, two experimental treatments (REGN-EB3 and mAb114) are associated with improved outcomes. The U.S. Food and Drug Administration (FDA) advises people to be careful of advertisements making unverified or fraudulent claims of benefits supposedly gained from various anti-Ebola products.

Treatment is primarily supportive in nature. Early supportive care with re-hydration and symptomatic treatment improves survival. Re-hydration may be via the oral or intravenous route. These measures may include pain management, and treatment for nausea, fever, and anxiety. The World Health Organization (WHO) recommends avoiding aspirin or ibuprofen for pain management, due to the risk of bleeding associated with these medications.

Blood products such as packed red blood cells, platelets, or fresh frozen plasma may also be used. Other regulators of coagulation have also been tried including heparin in an effort to prevent disseminated intravascular coagulation and clotting factors to decrease bleeding. Antimalarial medications and antibiotics are often used before the diagnosis is confirmed, though there is no evidence to suggest such treatment helps. Several experimental treatments are being studied.

Where hospital care is not possible, the WHO‘s guidelines for home care have been relatively successful. Recommendations include using towels soaked in a bleach solution when moving infected people or bodies and also applying bleach on stains. It is also recommended that the caregivers wash hands with bleach solutions and cover their mouth and nose with a cloth, obviously appropriate PPE would be a much better option.

Intensive care is often used in the developed world. This may include maintaining blood volume and electrolytes (salts) balance as well as treating any bacterial infections that may develop. Dialysis may be needed for kidney failure, and extracorporeal membrane oxygenation may be used for lung dysfunction.


Ebola has a risk of death in those infected, between 25% and 90%. As of September 2014, the average risk of death among those infected is 50%. The highest risk of death was 90% in the 2002–2003 Republic of the Congo outbreak.

Death, if it occurs, follows typically six to sixteen days after symptoms appear and is often due to low blood pressure from fluid loss. Early supportive care to prevent dehydration may reduce the risk of death.

Infection Control

People who care for those infected with Ebola should wear protective clothing including masks, gloves, gowns and goggles. The U.S. Centers for Disease Control (CDC) recommend that the protective gear leaves no skin exposed. These measures are also recommended for those who may handle objects contaminated by an infected person’s body fluids. When you suit up, an observer with a checklist should be watching each step of the process to ensure they are done correctly.

Donning PPE

The U.S. Centers for Disease Control publishes a series of videos which show how to perform these actions.

  1. Examine PPE equipment
  2. Clean Hands
  3. Boots and boot covers
  4. Inner gloves
  5. Coverall
  6. Respirator
  7. Surgical hood
  8. Outer apron
  9. Outer gloves
  10. Face shield
  11. Verify

If you have a powered air purifying respirator you can substitute steps 6 and 7 with donning the powered respirator and hood.

Removing PPE

The U.S. Centers for Disease Control publishes a series of videos which show how to perform these actions.

  • Prepare to remove your PPE
  • Engage your observer
  • Disinfect outer gloves
  • Remove outer apron (if used)
  • Disinfect outer gloves
  • Remove and discard outer gloves
  • Inspect and disinfect inner gloves
  • Remove the face shield
  • Disinfect inner gloves
  • Remove the surgical hood
  • Disinfect inner gloves
  • Remove the coverall
  • Disinfect inner gloves
  • Remove boot covers
  • Disinfect inner gloves
  • Change inner gloves
  • Remove respirator
  • Disinfect the new inner gloves
  • Disinfect your shoes
  • Disinfect inner gloves
  • Remove and discard inner gloves
  • Perform hand hygiene
  • Review body for contaminants
  • Exit the PPE removal area

Infected Persons

An infected person should be in barrier-isolation from other people. All equipment, medical waste, patient waste and surfaces that may have come into contact with body fluids need to be disinfected.

If a person with Ebola disease dies, direct contact with the body should be avoided.


Ebolaviruses can be eliminated with heat (heating for 30 to 60 minutes at 60 °C or boiling for 5 minutes). To disinfect surfaces, some lipid solvents such as some alcohol-based products, detergents, sodium hypochlorite (bleach) or calcium hypochlorite (bleaching powder), and other suitable disinfectants may be used at appropriate concentrations.