Ebola Virus Disease (EVD)
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Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans. The Ebola virus causes an acute, serious illness which is often fatal if untreated. Ebola virus disease (EVD) first appeared in 1976 in two simultaneous outbreak; one is 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.

The family of the virus filofiviridae is made up of three genera:

  • Cuevavirus,
  • Marburgvirus, and
  • Ebolavirus

And within the genus Ebolavirus, there are five species that have been identified. They are:

  • Zaire,
  • Bundibugyo,
  • Sudan,
  • Reston and
  • Taï Forest.

Fruit bats of the family Pteropodidae are said to be the natural Ebola virus hosts. 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 is the source of introduction of the virus to the human population.

Once the virus spreads to human, human-to-human transmission becomes easy through 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 such as bedding and clothing, contaminated with these fluids.

Ebola cannot be spread through the air, by water or by food. In Africa, however, Ebola may be spread as a result of handling bushmeat and contact with infected bats. It has not been proved that mosquitoes or other insects can transmit Ebola virus. Only a few species of mammals such as humans, bats, monkeys, and apes) have shown the ability to become infected with and spread Ebola virus.

Ebola has a way of mimicking the signs and symptoms of some common diseases with the presentation of symptoms similar to those of the common diseases. The symptoms may present 2 to 21 days after infection but the average is 8 to 10 days and usually include:

  • Fever
  • Severe headache
  • Muscle pain
  • Weakness
  • Fatigue
  • Diarrhea
  • Vomiting
  • Abdominal (stomach) pain
  • Unexplained hemorrhage (bleeding or bruising)

And as the condition becomes worse, bleeding inside the body, as well as from the eyes, ears, and nose occurs. Sometimes infected persons may vomit or cough up blood, have bloody diarrhea, and get a rash.

Recovery from Ebola depends on good supportive clinical care and the patient’s immune response. People who recover from Ebola infection develop antibodies that last for at least 10 years.


The diagnosis of Ebola virus in an individual who is at the early stage of the infection is usually problematic, this is because the early symptoms, such as fever, severe headache, may not indicate Ebola infection as it may mimic other common tropical diseases such as malaria and enteric fever.

In the diagnosis of Ebola, the following samples may be tested:

  • Blood or body fluids from a person sick with or who has died from Ebola,
  • Objects that have been contaminated with the blood or body fluids of a person sick with or who has died from Ebola,
  • Infected fruit bats and primates (apes and monkeys), or
  • Semen from a man who has recovered from Ebola

Samples from the patient can then be collected and tested to confirm infection.

Ebola virus is detected in blood only after onset of symptoms, most notably fever, which accompanies the rise in circulating virus within the patient’s body. It may take up to three days after symptoms start for the virus to reach detectable levels. Laboratory tests used in diagnosis include:

Within few days, after the disease has set in:

  • Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing
  • Polymerase chain reaction (PCR)
  • Virus isolation

Later in disease course or after recovery:

  • IgM and IgG antibodies

Retrospectively in deceased patients:

  • Immunohistochemistry testing
  • PCR
  • Virus isolation

Current WHO recommended tests include:

  • Automated or semi-automated Nucleic Acid Tests (NAT) for routine diagnostic management.
  • Rapid antigen detection tests for use in remote settings where NATs are not readily available. These tests are recommended for screening purposes as part of surveillance activities, however, reactive tests should be confirmed with NATs.

The preferred specimens for diagnosis include:

  • Whole blood collected in ethylenediaminetetraacetic acid (EDTA) from live patients exhibiting symptoms.
  • Oral fluid specimen stored in universal transport medium collected from deceased patients or when blood collection is not possible.

Samples collected from patients are an extreme biohazard risk; laboratory testing on non-inactivated samples should be conducted under maximum biological containment conditions. All biological specimens should be packaged using the triple packaging system when transported locally and internationally.

Healthcare providers caring for Ebola patients and family and friends in close contact with Ebola patients are at the highest risk of getting sick because they may come in contact with infected blood or body fluids. Ebola also can be spread through direct contact with objects, such as clothes, bedding, needles, syringes/sharps or medical equipment, that have been contaminated with infected body fluids. Additionally, people can become sick with Ebola after coming in contact with infected wildlife. For example, in Africa, Ebola may spread as a result of handling bushmeat and contact with infected bats.

It is also possible that Ebola could be spread through sex or other contacts with semen from men who have survived Ebola. Until more information is known, avoid contact with semen from a man who has had Ebola. It is not known if Ebola can be spread through sex or other contacts with vaginal fluids from a woman who has had Ebola.

There is currently no cure for Ebola; however, the disease can be managed by palliative measures which involve the treatment of the symptoms and complications.

The following basic interventions, when used early, can significantly improve the chances of survival:

  • Intravenous fluids (IV) and balancing electrolytes (body salts).
  • Maintaining the oxygen status and blood pressure.
  • Transfusion of whole blood.
  • Treating other infections whenever they present.

Extensive research work is on-going in finding the cure and permanent solution to the menace of this deadly viral disease.

Good supportive care and the patient’s immune response determine the recovery of the patient from Ebola depends on. People who recover from Ebola infection develop antibodies that last for at least 10 years, possibly longer. It is not known if people who recover are immune for life or if they can become infected with a different species of Ebola. Some people who have recovered from Ebola have developed long-term complications, such as joint and vision problems.

Ebola is still found to be present in the semen of man even after recovery. Its total disappearance from the semen varies from man to man.

The following can be done by people who travel to an area where cases of Ebola are being reported:

  • Careful hygiene practice. For example, wash your hands with soap and water or an alcohol-based hand sanitizer and avoid contact with blood and body fluids such as urine, feces, saliva, sweat, urine, vomit, breast milk, semen, and vaginal fluids.
  • Do not handle items that may have come in contact with an infected person’s blood or body fluids such as clothes, bedding, needles, and medical equipment.
  • 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 facilities in West Africa where Ebola patients are being treated.
  • Avoid contact with semen from a man who has had Ebola until you know Ebola is gone from his semen.
  • After returning, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola.

Healthcare workers who may be exposed to people with Ebola should follow these steps:

  • Wear appropriate personal protective equipment (PPE).
  • Practice proper infection control and sterilization measures. For more information, see U.S. Healthcare Workers and Settings.
  • Isolate patients with Ebola from other patients.
  • Avoid direct, unprotected 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 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.


Ebola. WebMD 2016
Centers for Disease Control and Prevention. July 22, 2015
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
Division of High-Consequence Pathogens and Pathology (DHCPP)
Viral Special Pathogens Branch (VSPB)

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