Ebola Viral Disease (EVD)

Key Features

Essentials of Diagnosis

• Early stage EVD presents as a nonspecific febrile illness

• Later stage EVD typically includes severe gastrointestinal symptoms, followed by neurologic ones and hypovolemic shock

• Hemorrhagic manifestations occur late in course

• Uveitis is prominent ocular finding

• Travel and contact history from an Ebola-affected country raise suspicion

• Diagnosis is confirmed by detection of virus with a real-time polymerase chain reaction

General Considerations

• The first Ebola outbreak occurred in 1976 as a simultaneous epidemic in the Democratic Republic of Congo and South Sudan

• The number of EVD cases spread rapidly; there are at least 10 affected countries, especially Guinea, Liberia, and Sierra Leone. Many cases and deaths in these countries occurred among health care workers.

• As of November 2019, 3298 probable and confirmed cases (and 2197 deaths) were reported from 28 health zones in the Democratic Republic of Congo, including 163 cases among health care workers

• Countries with effective viral containment include Sierra Leone, Liberia and Guinea. Outbreaks in the Democratic Republic of Congo have been reported as of 2018.

• Four species cause human disease

  • Species: Zaire ebolavirus; virus: Ebola virus (EBOV)

  • Species: Sudan ebolavirus; virus: Sudan virus

  • Species: Taï Forest ebolavirus; virus: Taï Forest virus (TAFV)

  • Species: Bundibugyo ebolavirus; virus: Bundibugyo virus

• Transmission

  • Occurs from direct contact with infected body fluids

  • No evidence supporting airborne transmission

  • However, the virus aerosolizes, meaning that certain settings such as health facilities carry additional risk

  • Virus must enter the body via mucous membranes, nonintact skin, sexual intercourse (virus has been detected in semen up to 9 months after recovery from infection), breastfeeding, or needlestick

  • Prior to symptoms, Ebola is not transmitted

• Ebola has a 2- to 21-day incubation period (average is 8–10 days)

Clinical Findings

Symptoms and Signs

• Early stage EVD

  • Headache

  • Weakness

  • Dizziness

  • Fever

  • Malaise, fatigue

  • Myalgia, arthralgia

• Later stage EVD (after 3–5 days)

  • Abdominal pain, severe nausea, vomiting, and diarrhea accompanying the febrile illness

  • Encephalitis is commonly observed and includes

    • Confusion

    • Slowed cognition

    • Agitation

    • Occasional seizures

  • Hypovolemic shock develops in most patients

  • However, hemorrhagic manifestations (gastrointestinal bleeding, diffuse mucosal bleeding, conjunctival bleeding) develop in only 1–5% of patients

  • Respiratory symptoms (ie, cough) are not typical, although interstitial pneumonia and respiratory failure are reported

Differential Diagnosis

• Varies with the stage of illness

• Early stage EVD

  • Malaria, typhoid, and other viral illnesses

  • Viral hepatitis

  • Toxins

  • Leptospirosis

  • Rickettsial diseases

• In later stage EVD

  • Bacterial, viral, and parasitic illnesses, including cholera

  • In children, rotavirus infection, which can present with severe gastroenteritis and shock

  • Encephalitis must be differentiated from the confusion associated with acute kidney injury and other neurologic manifestations

• As nonspecific symptoms progress to a severe systemic inflammatory response, coagulopathy with evidence of platelet dysfunction and DIC often ...