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Ebola Virus Infection

Practice Essentials

Ebola virus is one of at least 30 known viruses capable of causing viral hemorrhagic fever syndrome. The genus Ebolavirus is currently classified into 5 separate species: Sudan ebolavirus, Zaire ebolavirus, Tai Forest (Ivory Coast) ebolavirus, Reston ebolavirus, and Bundibugyo ebolavirus. The outbreak of Ebola virus disease in West Africa from 2014 to 2016, involving Zaire ebolavirus, was the largest outbreak of Ebola virus disease in history.

Ebola virus. Courtesy of the US Centers for Diseas

Ebola virus. Courtesy of the US Centers for Disease Control and Prevention.

As of September 17, 2019, an active outbreak of Ebola virus disease in the Democratic Republic of the Congo (DRC) had resulted in 3,034 confirmed and 111 probable cases of Ebola virus disease, including 2,103 attributable deaths.
An experimental vaccine has been credited with limiting the outbreak’s scope.

Signs and symptoms

The following 2 types of exposure history are recognized:

Primary exposure – This typically involves travel to or work in an Ebola-endemic area.

Secondary exposure – This refers to human-to-human exposure (eg, medical caregivers, family caregivers, or persons who prepared deceased patients for burial), primate-to-human exposure (eg, animal care workers who provide care for primates), or persons who collect or prepare bush meat for human consumption.

Physical findings depend on the stage of disease at the time of presentation. With African-derived Ebolavirus infection, there is an incubation period (typically 3-8 days in primary cases and slightly longer in secondary cases).

Early findings may include the following:

Fever

Pharyngitis

Severe constitutional signs and symptoms

Maculopapular rash (best seen in white patients)

Bilateral conjunctival injection

Later findings may include the following:

Expressionless facies

Bleeding from intravenous (IV) puncture sites and mucous membranes

Myocarditis and pulmonary edema

In terminally ill patients, tachypnea, hypotension, anuria, and coma

Survivors of Ebola virus disease have developed the following late manifestations:

Myalgias

Asymmetric and migratory arthralgias

Headache

Fatigue

Bulimia

Amenorrhea

Hearing loss

Tinnitus

Unilateral orchitis

Suppurative parotitis

Diagnosis

Diagnostic studies that may be helpful include the following:

Basic blood tests – Complete blood count (CBC) with differential, bilirubin, liver enzymes, blood urea nitrogen (BUN), creatinine, pH

Studies for isolating the virus – Tissue culture (only to be performed in one of a few high-containment laboratories throughout the world), reverse-transcription polymerase chain reaction (RT-PCR) assay

Serologic testing – Enzyme-linked immunosorbent assay (ELISA) for antigens or for immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies

Other studies – Immunochemical testing of postmortem skin, electron microscopy

Management

General principles of care are as follows:

Supportive therapy with attention to intravascular volume, electrolytes, nutrition, and comfort care is of benefit to the patient.

Such therapy must be administered with strict attention to barrier isolation; all body fluids contain infectious virions and should be handled with great care.

No specific therapy is available that has demonstrated efficacy in the treatment of Ebola hemorrhagic fever.

Ebola Zaire vaccine is approved in Europe and the United States. The live recombinant vaccine has shown effectiveness of 97.5% in preventing infection among 90,000 individuals in an active Ebola virus outbreak in the Democratic Republic of Congo.

The FDA approved
atoltivimab/maftivimab/odesivimab (Inmazeb), a recombinant human monoclonal antibody combination. These antibodies target the glycoprotein (GP) on the Ebola virus surface, thereby blocking attachment and entry of the virus on host cell membranes.

 

Other agents that have been studied for the treatment or prevention of Ebola virus disease include the following:

Ribavirin (possesses no demonstrable anti-
Ebolavirus activity in vitro and has failed to protect
Ebolavirus -infected primates)

Nucleoside analogue inhibitors of S-adenosylhomocysteine hydrolase (SAH)

Interferon beta

Horse- or goat-derived immune globulins

Human-derived convalescent immune globulin preparations

Recombinant human monoclonal antibodies

Recombinant human interferon alfa-2

Activated protein C

Recombinant inhibitor of factor VIIa/tissue factor

In those patients who do recover, recovery often requires months, and delays may be expected before full resumption of normal activities. Weight gain and return of strength are slow. Ebola virus continues to be present for many weeks after resolution of the clinical illness.

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