Ebola Hemorrhagic Fever: A Primer

The Ebola outbreak in West Africa appears ever more worrisome. Since it is likely that a sick traveler will arrive in the United States and since most physicians and infection preventionists have never dealt with the disease, I thought it would be good to put together a quick review.

Epidemiology

• The current outbreak in Guinea, Liberia, and Sierra Leone is the largest ever recorded, with approximately 1200 cases to date, and ~60% mortality.
• The natural reservoir of the virus (a filovirus) is suspected to be bats.
• Transmission occurs via contact with infected human body fluids (blood, saliva, vomitus, stool, semen, breast milk, and tears).
• Nosocomial transmission is a key driver of outbreaks.
• Transmission has not been demonstrated from individuals who are in the asymptomatic incubation period.

Clinical

• The incubation period is 2-21 days (usually 5-7 days).
• The illness is characterized by abrupt onset of fever, chills, myalgias and malaise. This is followed by GI symptoms (nausea, vomiting, diarrhea and abdominal pain), cough, headache, and conjunctival hemorrhages. 
• Hemorrhagic symptoms usually occur at the peak of illness and include maculopapular rash, petechiae, bruising, and bleeding from venipuncture sites. Gross bleeding from the GI and GU tracts is usually only seen in dying patients.
• The late stage of disease is manifested by shock, capillary leak syndrome, seizures, delerium, coma, bleeding and anuria.
• Laboratory findings include leukopenia, thrombocytopenia, elevated transaminases, proteinuria, and markers of DIC. 
• In survivors, the convalescent phase is long.
• Ebola Fever should be suspected in a patient with a history of travel to an outbreak area who has fever, myalgias, and two of the following (rash, nosebleed, hematemesis, hemoptysis, hematochezia).

Diagnostic Testing 

• In the US, all testing is performed by public health laboratories.
• Available testing includes antibody testing (ELISA), PCR and viral culture.

Treatment

• No specific antiviral therapy is currently available.
• Treatment is focused on supportive care.
• Corticosteroids, nonsteroidal anti-inflammatory drugs, and aspirin are contraindicated.

Infection Control and Prevention (CDC guidance here)

• Contact and droplet precautions are indicated for suspected and confirmed cases.
• Airborne precautions should be used for aerosol-generating procedures.
• Eye protection (goggles or face shield) is specifically recommended.
• Some experts also recommend double gloving and shoe covers.
• Careful removal of PPE followed by hand washing is imperative.
• At this time, there is no available vaccine or chemoprophylaxis.

Resources:

• CDC Ebola site
• WHO Ebola site
• WHO Ebola infection control recommendations

Photo: Frederick Murphy, CDC.