Ebola virus disease

Ebola virus disease (EVD) (also known as Ebola hemorrhagic fever (EHF) or simply Ebola) is a viral hemorrhagic disease caused by the Ebola filovirus. Ebola is an extremely virulent virus with a case fatality rate of ~70% ¹.

Epidemiology

First recognized in 1967 after polio vaccine laboratory workers were exposed to infected primates brought to Europe from Africa. The first outbreak occurred in 1976 in Zaire (since 1997 the Democratic Republic of the Cοngo), killing 318 people ². A more recent outbreak which started in March 2014 and ended in 2016, involved multiple countries, spanning three continents and represented the largest known outbreak in history with 28,652 probable and confirmed cases, and 11,325 deaths ².

Clinical presentation

The initial clinical syndrome is non-specific and features flu-like symptoms such as fever, myalgia, and general malaise. This is followed by nausea, vomiting, diarrhea, and rashes progressing to petechiae, conjunctival hemorrhage, epistaxis, melena, hematemesis, shock and encephalopathy ³.

Pathology

The incubation period of the virus is 2-21 days. 

Transmission

It occurs by coming in direct contact with infected fluid like blood, breast milk, semen, saliva, sweat, feces, and vomit, through broken skin, mucous membranes or contaminated medical equipment.

Radiographic features

Due to the fact that Ebola is predominantly a disease of resource-poor areas, little data on specific imaging features of Ebola exists. However, necropsy studies on non-human primates suggest that aerosolized virus would be unlikely to produce discrete, radiographically visible, pulmonary lesions ⁴.

Treatment and prognosis

Recent research has yielded not only the possibility of a vaccine ⁵ but also treatments for patients with Ebola including the drug now marketed as Inmazeb. The Pamoja Tulinde Maisha/PALM trial of various treatments yielded positive results for two drugs ⁶ . Survivors of Ebola suffer long term sequelae ⁷.

History and etymology

Ebola is named after a river called l’Ebola near the village where the virus was first isolated in what is now the Democratic Republic of the Congo (the country was called Zaire at the time of disease discovery) ⁸. 

Differential diagnosis

The differential diagnosis for Ebola includes other hemorrhagic fevers such as Marburg hemorrhagic fever, Lassa fever and Crimean-Congo hemorrhagic fever.