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Ebola virus disease (EVD; Ebola haemorrhagic fever)

Ebola Virus Disease
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What is Ebola Virus Disease?

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Ebola virus disease, previously called Ebola Haemorrhagic fever, is a serious disease caused by infection with the Ebola virus.

The disease was first discovered in 1976 near the Ebola river (now the Democratic Republic of the Congo) and outbreaks continue to occur in Africa. Some of the areas that have seen Ebola virus disease outbreaks include: the Democratic Republic of the Congo (DRC), Gabon, South Sudan, Ivory Coast, Uganda, Republic of the Congo (ROC) and imported cases in South Africa.

The most recent outbreak began in March 2014 with cases first reported in Guinea, followed by the surrounding regions of Liberia, Sierra Leone and Nigeria. This outbreak is the first in West Africa and is considered to be the largest in Ebola history, with more cases and deaths in this outbreak than all the others combined.

Occurring at the same time as the outbreak in West Africa, there is an Ebola virus outbreak in the Democratic Republic of the Congo. This is believed to be unrelated to the outbreak in West Africa.
There has never been a case of Ebola Virus Disease in Australia.

The natural source of infection of the Ebola virus remains unknown, however, fruit bats are believed to be the most likely source. Occasionally, the Ebola virus can infect and cause disease in animals such as monkeys, gorillas and chimpanzees.

Statistics

Ebola virus disease occurs at irregular intervals in time (sporadic) and hence the number of cases that occur over time (incidence) varies depending on time as well as different areas or countries.africa_disease_cure_syringe_epidemic_400x300

In the 2014 West African outbreak of Ebola virus disease, the total number of probable, confirmed and suspected cases is 8,997 (as of 15th October 2014) with 4,493 deaths.

There have been no cases of Ebola virus disease identified in Australia and hence the incidence of Ebola virus disease in Australia is currently zero.

There have been confirmed cases in Senegal (1 case), Spain (1 case) and the United States (2 cases) related to patients travelling from West Africa.

Risk Factors

There are several factors that may increase the chances of an individual becoming infected with the Ebola virus. These are largely related to that person’s risk of becoming exposed to the virus. They include:

  • People who are living in or travelling to affected areas of Africa, although this risk is extremely low unless there has been direct exposure to the bodily fluids of an infected person or animal;
  • Caring for those infected with Ebola virus, especially in areas with inadequate infection control; and/or
  • Coming into contact with the body of an infected person or animal after death, including the handling of bushmeat.

Progression of Ebola Virus Disease

The manner in which the Ebola virus first infects a human at the start of an outbreak is unknown, however, researchers believe that first human becomes infected through contact with an infected animal. The natural source of the Ebola virus has not yet been identified, although the most likely host is thought to be bats. Humans can also be exposed from coming into contact with infected dead animals such as the handling of bushmeat.

Once infected, the time interval between infection and onset of symptoms (incubation period) is between 2 and 21 days. Humans infected with the virus are not considered infectious until they develop symptoms. The symptoms produced from infection with Ebola virus are discussed in more detail under the subheading of Symptoms of Ebola virus disease.

Spread from human to human is through contact with blood and/or bodily fluids (urine, saliva, faeces, vomit, sweat, breast milk and semen) of infected individuals. This may be through direct contact and/or droplet spread (droplets of infected bodily fluids produced by sneezing, coughing or talking) or via objects (such as needles) and environments that have been contaminated with the virus. Ebola has been found in semen for up to three months and it is therefore advised that infected persons/those that have recovered abstain from sex or use condoms for 3 months post infection. Ebola is not thought to be spread via the water.

Once the Ebola virus enters the body it affects the infected person’s blood coagulation (how the blood clots to prevent bleeding) and immune defense (how the body fights infection) pathways. The percentage of people that die from Ebola virus infection is between 50-90%.

People and animals remain infectious from the moment they first have symptoms until as long as their blood/body fluids contain the virus. Those that recover from infection with Ebola virus develop antibodies that last for a minimum of 10 years.

Prevention

Currently there is no vaccine available for Ebola virus disease. However, a number of companies are working on this with two potential vaccines currently undergoing testing for their safety in humans.

Current strategies to prevent infection include:african_nurse_african_patient_drawing_blood_400x300

  • Monitoring areas with identified cases;
  • Isolating cases to minimise the spread to other persons;
  • Tracing the contacts (contact tracing) of cases to stop the chain of transmission;
  • Engaging and educating the community, including education about safe burial practices;
  • Raising awareness of risk factors for Ebola virus infection and protective measures that an individual can take to minimise their risk;
  • Strict infection control (measures taken to reduce spread of infection) within healthcare environments.

The CDC has issued the following set of recommendations for those travelling to or in an area affected by an Ebola outbreak:

  • Practice careful hygiene including avoidance of contact with blood and body fluids.
  • Do not handle items that may have come in contact with an infected person’s blood or body fluids.
  • Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola.
  • Avoid contact with bats and nonhuman primates or blood, fluids, and raw meat prepared from these animals.
  • Avoid hospitals where Ebola patients are being treated.
  • After you return, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola.

If you are a healthcare worker, added recommendations include:

  • Wear protective clothing, including masks, gloves, gowns, and eye protection.
  • Practice proper infection control and sterilization measures.
  • Isolate patients with Ebola from other patients.
  • Avoid direct contact with the bodies of people who have died from Ebola.
  • Notify health officials if you have had direct contact with the blood or body fluids, such as but not limited to, feces, saliva, urine, vomit, and semen of a person who is sick with Ebola. The virus can enter the body through broken skin or unprotected mucous membranes in, for example, the eyes, nose, or mouth.

Breastfeeding

The Ebola virus has been found in the breastmilk of breastfeeding mothers. However, it is not yet known if breastfeeding will pass the virus onto the child and cause infection. What is known is that infants of mothers infected with Ebola virus have a high risk of developing the disease, but this may just be because of the close contact between mother and baby. The decision to continue to breastfeed, if infected with Ebola virus, must be made on an individual basis. Things to consider include:

  • the age of the child?
  • if alternative nutrition available?
  • the sanitary conditions available?

For example in areas that are resource poor, there may be no other available and/or safe option than to breastfeed, for example if there is no clean water to prepare formula or formula may just not be available.

Symptoms of Ebola Virus Disease

Signs and symptoms of Ebola virus disease occur anywhere between 2-21 days post infection with the virus, although symptoms typically appear within 8-10 days. Early signs of infection are often non-specific and resemble a flu-like illness including:

  • Fever,200470326-001
  • Neurological complaints such as confusi
  • Fatigue,
  • Headache, and/or
  • Aching muscles.

Later signs of infection include:

  • Gastrointestinal complaints such as vomiting and/or diarrhoea;on and/or coma;
  • Cardiovascular symptoms including changes in blood pressure and swelling of the limbs;
  • Respiratory symptoms including sore throat and cough; and/or
  • Rash.

Patients may later develop multi-organ failure in which vital organs such as the liver and kidneys fail to function adequately. This may or may not be accompanied by heavy bleeding.

Pregnant women will usually abort their foetuses and suffer heavy bleeding.

Clinical examination

The examination findings will vary depending on the stage of disease at the time of examination.
Early in the course of the disease your Doctor may examine your:

  • Temperature to see if you have a fever;
  • Eyes to see if they are bloodshot;
  • Skin for evidence of a rash (especially on the torso, more evident on lighter skin and usually shows from around day 5 of infection); and/or
  • Mouth for evidence of a sore throat.

As the disease progresses, examination may show:

  • Changes to facial expressions
  • Bleeding
  • Signs of shock: increased heart rate, low blood pressure, reduced urine production
  • Signs of fluid on the lungs (pulmonary oedema)
  • Reduced consciousness

How is Ebola Virus Disease diagnosed?

Ebola disease is diagnosed by a series of test that are performed depending on the patients symptoms and if there is a history to support likely exposure to the virus as discussed in Risk factors.ebola_virus_blood_sample

Samples that may be taken for testing include:

  • Blood samples;
  • Throat swabs; and/or
  • Urine.

A number of different scientific tests can then be done on these samples to diagnose Ebola virus disease. The most common method involves looking for the genetic material of the virus in the samples provided.

How is it treated?

Currently there is no specific treatment for Ebola virus disease, however, there are a number of potential treatments currently being investigated.
Supportive care involves the use of:

  • fluid and electrolyte replacement / balance;
  • maintaining oxygen status;
  • maintaining blood pressure;
  • treatment of complicating infections; and
  • treatment of specific symptoms as they appear;

Those that recover from Ebola virus disease develop antibodies against the virus that persist for 10 years and possibly longer.

Kindly written and reviewed by Dr Allison Johns Bsc (Hons) MBBS, Doctor at Child and Adolescent Health Services and Editorial Advisory Board Member of Virtual Medical Centre.

References

  1. Centers for Disease Control and Prevention. About Ebola Virus Disease (online). 18th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  2. World Health Organisation. Ebola Virus Disease (online). September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  3. Public Health Agency of Canada. Ebolavirus: pathogen safety data sheet (online). 22nd August 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  4. Australian Government, The Department of Health. Ebola Virus Disease: CDNA national guidelines for public health units (online). 15th August 2014 [Accessed 21/09/2014]. Available from: (PDF File)
  5. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): risk of exposure. 13th August 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  6. Centers for Disease Control and Prevention. 2014 Ebola Outbreak in West Africa (online). 18th September 2014. [Accessed 21/09/2014]. Available from: (URL Link)
  7. Centers for Disease Control and Prevention. Fact Sheet: CDC Ebola Surge 2014 (online). 16th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  8. World Health Organisation. Ebola Response Roadmap Situation Report (online). 18th September 2014 [Accessed 21/09/2014]. Available from: (PDF File)
  9. Government of South Australia, SA Health. Ebola virus disease for health professional (online). 28th August 2014 [Accessed 21/09/214]. Available from: (URL Link)
  10. European Centre for Disease Prevention and Control. Rapid risk assessment: Outbreak of Ebola virus disease in West Africa (online). 8th April 2014 [Accessed 21/09/2014]. Available from: (PDF File)
  11. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): Case Definition for Ebola Virus Disease. 5th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  12. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): transmission (online). 18th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  13. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): signs and symptoms (online). 18th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  14. Centers for Disease Control and Prevention. Questions and answers on experimental treatments and vaccines for Ebola (online). 29th August 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  15. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): prevention. 19th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  16. Australian Government, The Department of Health. Ebola Virus Disease (EVD) outbreaks in West Africa: Information for GPs (online). 15th August 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  17. Royal Australasian College of General Practitioners. Practice standards: RACGP infection prevention and control standards 5th edition (online). May 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  18. National Health and Medical Research Council. Australian guidelines for the prevention and control of infection in healthcare. 2010 [Accessed 21/09/2014]. Available from: (URL Link)
  19. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): diagnosis. 19th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  20. Australian Government, The Department of Health. Ebola Virus Disease (EVD) outbreaks in West Africa: Information for Clinicians (online). 15th August 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  21. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): treatment. 19th September 2014 [Accessed 21/09/2014]. Available from: (URL Link)
  22. Ebola virus infection clinical presentation (online). 4th September 2014 [Accessed 22/09/2014]. Available from: (URL Link)
  23. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): Recommendations for Breastfeeding/Infant Feeding in the Context of Ebola. 19th September 2014 [Accessed 16/10/2014]. Available from: (URL Link)
  24. Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease): 2014 Ebola Outbreak in West Africa – Case Counts. 15th September 2014 [Accessed 16/10/2014]. Available from: (URL Link)
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Dates

Posted On: 22 December, 2003
Modified On: 31 May, 2018
Reviewed On: 18 October, 2014

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