Ebola Virus Disease



Ebola virus disease (EVD) is a severe often fatal disease in humans and non-human primates (monkeys, gorillas and chimpanzees).


  • Ebola virus disease 1st appeared in 1976.
  • The disease is caused by infection with ebola virus, named after a river in the Democratic Republic of the Congo (formerly Zaire) in Africa, where it was first recognized.

Causative Agent

  • Ebola virus is classified in the genus Ebolavirus, family Filoviridae, order Mononegavirals.
  • Ebolavirons are filamentous particles that may appear in the shape of shepherd’s crook or in the shape of a "U" or a "6“.
  • Ebolavirons contain linear non-segmented, single stranded, non-infectious RNA genomes.


  • Bats are considered the most likely natural reservoir of ebola virus.
  • Plants, arthropods, and birds were also considered.

Mode of transmission

  • Humans handle and eat bush meat (bats, chimpanzees, gorillas).
  • Human to human transmission occurs only via direct contact with blood or body fluids from an infected person or by contact with objects contaminated by the virus, especially needles and syringes.
  • Body fluids that may transmit ebola virus include saliva, mucous, vomitus, feces, sweat, tears, breast milk, urine and semen.
  • Male survivors may be able to transmit the disease via semen for nearly 2 months.
  • Airborne transmission hasn’t been documented.

Clinical picture

  • Incubation period: 2-21 days.
  • Stage I (Nonspecific):

      - Early manifestations include influenza like stage with fever, malaise, chills,

       myalgia, severe headache and arthralgia.

       - Diarrhea, nausea , vomiting, anorexia  and abdominal pain.

       - Mucosal redness of the oral cavity, dysphagia (difficulty in     swallowing)

      -  Conjunctivitis.

      -  A maculopapular rash associated with varying severity of erythema

         appears 5-7 days of the illness and usually desquamate in survivors.

    ** If the patients don’t recover gradually at this point, there is a high probability that the disease will progress to the second phase, resulting in complications which eventually lead to death.

  • Stage II (Specific):

  - Haemorrhagic manifestations typically 5-7 days after first symptoms and include petechiae, ecchymosis, bleeding from puncture sites and mucous membranes “GIT, nose, vagina and gums”. Heavy bleeding is rare and is usually confined to the GIT.

     -  CNS symptoms: Headache, confusion and coma.

     - Respiratory: chest pain, shortness of breath and tachypnea.

    - Multi-organ dysfunction: kidneys and Liver.

   - In late stages shock, convulsions, severe metabolic disturbances and DIC  


    ** Patients who progressed to phase two almost always die.

Laboratory findings:

  • Are less characteristic including:
  • Early leucopenia with lymphopenia and subsequent neutrophilia, atypical lymphocytes. In late stages there is leucocytosis.
  • Highly raised serum transaminases.
  • PT and PTT are prolonged and FDP may be detectable.

Diagnosis of EVD

  • Antigen detection by ELISA.
  • Antibody detection by ELISA.
  • Virus isolation.

Differential diagnosis

  • Marburg virus disease.
  • Other viral hemorrhagic fevers.
  • Falciparum malaria.
  • Typhoid fever.
  • Rickettsial diseases.