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Ebola (Ebola Hemorrhagic Fever)
Topic Table of Contents

Quick Facts

Ebola (Ebola Hemorrhagic Fever)
  • Ebola is a very contagious disease with a high mortality rate. The incubation period from initial exposure to onset of acute disease symptoms is between 2 and 21 days with the average being 6 to 10 days.
  • Ebolavirus is spread through inhalation, ingestion and or passage through breaks in the skin when an uninfected person comes in contact with blood or other body fluids.
  • Ebola is also thought to be spread when a person comes in contact with bandages, clothes or other objects that have been contaminated with body fluids, especially blood, of an infected person.
  • There is some evidence that Ebola may be spread when an infected person coughs or sneezes into the air.
  • Depending upon the body fluid, Ebolavirus has been detected in body fluids from 6 to 40 days after disease onset, including during the convalescent stage.
  • Symptoms start with a fever, headache, muscle and stomach pain, diarrhea, vomiting, skin bruising and, in severe cases, can progress to septic shock and liver, kidney and other body organ failure with bleeding from the nose, mouth and gastrointestinal tract.
  • When used early, basic interventions like IV fluids, maintaining of oxygen and blood pressure levels and treatment of secondary infections when they occur can improve chances of survival.
  • Individuals who recover from Ebola may develop long-lasting immunity, but it is not known if immunity is life-long or if there is a susceptibility to infection from different strains of Ebola.
  • Long-term complications like joint and vision problems are possible. 
  • As of October 2014 there is no FDA approved Ebolavirus drug or vaccine licensed in the U.S.
Experimental Ebola Vaccines
  • As of October 2014 there are no FDA approved vaccines for Ebolavirus.
  • There are several experimental Ebolavirus vaccines that have been in development for more than a decade and are currently being tested to respond to the 2014 outbreak of Zaire ebolavirus.
  • Clinical trails for a few experimental vaccines are being conducted in the U.S., United Kingdom and Africa.
  • Preliminary data on experimental vaccines in clinical trials is estimated to be available late 2015 and may be fast tracked by FDA for widespread use.
Experimental Ebola Drug
  • As of October 2014 there are no FDA approved drugs for the treatment of Ebola.
  • ZMapp, an experimental therapeutic drug developed by Mapp Biopharmaceutical Inc., is designed to treat people infected with Ebola virus and is not designed to prevent infection.
  • ZMapp has been shown to prevent Ebola infection in monkeys and was the experimental drug given to two U.S. missionaries working in Liberia, who contracted Ebolavirus in 2014 and survived.
  • According to the CDC, “It is too early to know whether ZMapp is effective, since it is still in an experimental stage and has not yet been tested in humans for safety or effectiveness.”
NVIC “Quick Facts” is not a substitute for becoming fully informed about Ebola and experimental Ebola vaccines and drugs. Following our Quick Facts box is more complete information and references. NVIC doesn’t give medical advice and information provided is for informational purposes only. If you believe you have been exposed to Ebola, seek medical advice immediately.  

Centers for Disease Control (CDC)
Food and Drug Administration (FDA)
National Institutes of Health (NIH) and Affiliates
World Health Organization (WHO)
 

Table of Contents 

What is Ebola? What are experimental Ebola vaccines?
Is Ebola communicable? What is known about experimental Ebola vaccines?
History of Ebola Live links to NVIC Ebola press releases and referenced commentaries 
Can Ebola cause injury and death? Additional Federal Agency Resource Links
Ebola prevention and treatment options         Endnotes
Quick Facts

What is Ebola?

Ebola is a very contagious disease in non-human primates (monkeys, gorillas, and chimpanzees) and humans with a high mortality rate. The natural reservoir for the virus is thought to be a fruit bat living in Africa.1

Ebolavirus and Marburgvirus belong to the family Filoviridae and cause suppression of innate and adaptive immune responses that lead to a syndrome resembling septic shock.2 There are five species of Ebolavirus (Zaire, Sudan, Ivory Coast, Bundibugyo and Reston) and the 2014 Ebola outbreak is being caused Zaire ebolavirus.3

Symptoms start with a fever, headache, muscle and stomach pain, diarrhea, vomiting, skin bruising and, in severe cases, can progress to septic shock and liver, kidney and other body organ failure with bleeding from the nose, mouth and gastrointestinal tract.

Is Ebola Communicable?

Yes. Ebolavirus is spread through inhalation, ingestion and or passage through breaks in the skin when an uninfected person comes in contact with the body fluids (blood, saliva, nasal secretions, stool, vomit, breastmilk, semen, urine, tears) of an infected person or the cadaver of a person who died from Ebola.4 Ebola is also thought to be spread when a person comes in contact with bandages, clothes or other objects that have been contaminated with body fluids, especially blood, of an infected person.5 6

Depending upon the body fluid, Ebolavirus has been detected in body fluids from 6 to 40 days after disease onset, including during the convalescent stage.7

After coming in contact with someone infected with Ebola, the incubation period from initial exposure to onset of acute disease symptoms is between 2 and 21 days with the average being 6 to 10 days.8

There is some evidence that Ebola may be spread when an infected person coughs or sneezes into the air but there is disagreement among scientists and public health officials about whether or not airborne transmission does
occur.910111213

There is also disagreement about whether or not an infected person, who is not exhibiting a fever or other acute signs of illness, can still transmit infection to others.14 15

Those who recover from Ebola virus infection may develop antibodies lasting 10 years or longer, but it is not known if they can become immune for life or if they are susceptible to infection from different strains of Ebola virus.16

History of Ebola

The first Filovirus (Marburg) was identified in 1967 when about 30 laboratory workers in Germany and Yugoslavia developed hemorrhagic fever and seven died. The workers had handled kidney tissues from infected African green monkeys imported from Uganda when they were preparing primary cell cultures for polio vaccine production.17 18

Before a large outbreak in Guinea, Liberia and Sierra Leone in 2014, Ebola outbreaks during the past two decades were sporadic and primarily confined to Africa.19

Can Ebola Cause Injury and Death?

Yes. Historically, between 25 and 90% of Ebola cases have ended in death and the Africa-based outbreak that began in Guinea, Liberia and Sierra Leone in 2014 has been averaging a 40 to 70% case fatality rate.20 Individuals who recover from Ebola can experience long-term complications like joint and vision problems.21 

In non-fatal cases, health improvement is seen between days 6 and 11 after onset of symptoms.  In fatal cases, death usually occurs within 6 to 16 days.22

Ebola Prevention and Treatment Options

As of October 2014 there are no FDA approved vaccines for the prevention of Ebolavirus,23 though several are under development. 

Currently there are no FDA approved drugs for the treatment of Ebola and symptoms are treated as they develop. Treatment with intravenous fluids, maintaining oxygen and blood pressure levels and treatment of secondary infections when they occur “can significantly improve the chances of survival” when used early.24 

Mapp Biopharmaceutical Inc. has developed an experimental therapeutic drug, ZMapp, to treat infected individuals. According to the CDC “ZMapp is a combination of three monoclonal antibodies manufactured in tobacco plants. Monoclonal antibodies bind certain virus proteins and neutralize the virus, decreasing the amount of the virus in the body that the patient's immune system has to fight.”

ZMapp has been shown to prevent Ebola infection in monkeys and was the experimental drug given to two U.S. missionaries working in Liberia, who contracted Ebolavirus in 2014. These missionaries survived after being given ZMapp,25 26 however, the CDC has stated that this drug has not been fully tested in humans for safety or effectiveness.27

What are Experimental Ebola Vaccines?

There are several experimental Ebolavirus vaccines that have been in development for more than a decade and are currently being tested to respond to the 2014 outbreak of Zaire ebolavirus. One of the Ebola vaccines has been developed by the U.S. government and one by the Canadian government.28 There is another Ebolavirus vaccine being co-developed by a U.S. company and the Centers for Disease Control.29

The National Institute of Allergy and Infectious Diseases (NIAID) with GlaxoSmithKline (GSK) has developed a genetically engineered chimpanzee-derived adenovirus vectored Ebola vaccine with two inserted Ebolavirus genes (cAd3-ZEBOV).30 31  A U.S. clinical trial with 20 participants32 and a UK clinical trial with 60 participants are being conducted followed by clinical trials in two African countries each with 40 participants.33

The Public Health Agency of Canada has developed a genetically engineered Ebola vaccine (rVSV-ZEBOV) and the license for the vaccine is held by NewLink Genetics, a U.S. company. The Canadian Ebola vaccine uses an attenuated vesicular stomatitis virus, a pathogen that infects livestock (cattle, horses, deer, pigs) with one of its genes replaced by an Ebolavirus gene.34 35]

GeoVax Labs, Inc. is collaborating with the Centers for Disease Control to develop and test two experimental Ebola vaccines (GOVX-E301 and GOVX-E302) which are recombinant modified vaccinia Ankara (MVA) vaccines that will produce virus-like particles (VLPs) displaying the Ebola virus glycoprotein.36

What is Known about Experimental Ebola Vaccines?

As of October 2014 there are no FDA approved Ebola vaccines. Ebola vaccines in use are experimental and their safety and effectiveness are unknown.37

Preliminary data on the NIAID/GSK vaccine is estimated by December 2015 and the vaccine may be fast tracked by FDA into widespread use. A placebo controlled U.S. clinical trial of the VSV Ebola vaccine is scheduled to be completed in October 2015.38
 
Live Links to NVIC Referenced Commentaries & Press Releases on Ebola Virus
Additional Federal Agency Ebola Resource Information
Centers for Disease Control (CDC)
Food and Drug Administration (FDA)
National Institutes of Health (NIH)
World Health Organization (WHO)
Endnotes


2 Mahanty S, Bray M. Pathogenesis of filoviral haemorrhagic fevers. Lancet Infect Dis 2004; 8: 487-498.
 
3 Feldmann H. Ebola – A Growing Threat? N Engl J Med 2014; 371(15): 1375-1378.
 
4 Bray M, Hirsch MS, Mitty J. Epidemiology, pathogenesis, and clinical manifestations of Ebola and Marburg virus disease. Wolters Kluwer Health  UpToDate.com Oct. 9, 2014.
 
5 Khan AS, Tshioko K, Heymann DL et al. The Reemergence of Ebola Hemorrhagic Fever, Democratic Republic of the Congo, 1995. J Infec Dis 1999; 179 (Suppl 1): 576-586
 
6 Sagripanti JL, Lytle CD. Sensitivity to Ultraviolet Radiation of Lassa, Vaccinia and Ebola Viruses Dried on Surfaces. Arch Viol 2011; 156 (3): 489-494.
 
7 Bausch DG, Towner JS, Dowell SF et al. Assessment of the Risk of Ebola Virus Transmission From Bodily Fluids and Fomites. J Infect Dis 2007; 196 (Supplement 2): S142-S147.
 
8 World Health Organization (WHO). Ebola Virus Disease. WHO Fact Sheet September 2014.

9 Bray M, Hirsch MS, Mitty J. Epidemiology, pathogenesis, and clinical manifestations of Ebola and Marburg virus disease. Wolters Kluwer Health  UpToDate.com Oct. 9, 2014.
 
10 Brosseau LM, Jones R. Health Workers Need Optimal Protection for Ebola. CIDRAP Sept. 17, 2014
 
11 Willman D. Some Ebola Experts Worry Virus May Spread More Easily Than Assumed. Los Angeles Times Oct. 7, 2014.
 
12 Centers for Disease Control. CDC Case Definition for Ebola Virus Disease (EVD), Low Risk Exposures (“A low risk exposure includes any of the following: Household contact with an EVD patient; other close contact with EVD patients in health care facilities or community settings. Close contact is defined as (a) being within approximate 3 feet of an EVD patient or within the patient’s room or care area for a prolonged period of time while not wearing recommended personal protective equipment.”) CDC Website Sept. 5, 2014.
 
13 CDC. Ebola Transmission. Oct. 13, 2014. 
 
14 Altman LK. People Carrying Ebola, in Some Cases, May Be Free of Symptoms. New York Times June 27, 2000.
 
15 Leroy EM, Baize S, Volchkov VE et al. Human asymptomatic Ebola infection and strong inflammatory response. The Lancet 2000; 355 (9222): 2210-2215.
 
16 CDC. Ebola (Ebola Virus Disease) – Treatment. Accessed Oct. 14, 2014.
 
17 Bray M, Hirsch MS, Mitty J. Epidemiology, pathogenesis, and clinical manifestations of Ebola and Marburg virus disease. Wolters Kluwer Health  UpToDate.com Oct. 9, 2014
 
19 Centers for Disease Control (CDC). Ebola Outbreaks (2000 - 2014). Oct. 10, 2014.
 
20 World Health Organization (WHO). Ebola Virus Disease. WHO Fact Sheet September 2014.
 
21 CDC. Ebola (Ebola Virus Disease) – Treatment. Accessed Oct. 14, 2014.
 
22 Bray M, Hirsch MS, Mitty J. Epidemiology, pathogenesis, and clinical manifestations of Ebola and Marburg virus disease. Wolters Kluwer Health  UpToDate.com Oct. 9, 2014.
 
23 CDC. Ebola (Ebola Virus Disease) – Prevention. Accessed Oct. 14, 2014.

24 CDC. Ebola (Ebola Virus Disease) – Treatment. Accessed Oct. 14, 2014.
 
26 Wilson J, Dellorto D. 9 Questions About This New Ebola Drug. CNN Aug. 5, 2014
.
27 CDC. Ebola (Ebola Virus Disease) Questions & Answers on Experimental Treatments and Vaccines for Ebola – Are there Ebola vaccines available for use or in development?. Accessed Oct. 14, 2014.
 
28 WHO. Experimental Ebola Vaccines. Oct. 1, 2014.
 
29 Atlanta Business Chronicle. GeoVax Developing Two Ebola Vaccines. Oct. 3, 2014.
 
31 NIH. Ebola Vaccine Development. Sept. 8, 2014.
 
34 Geisbert TW, Feldman H. Recombinant Vesicular Stomatitis Virus-Based Vaccines Against Ebola and Marburg Virus Infections. J Infect Dis 2011; 204 (Supplement 3: S1075-S1081.
 
36 Atlanta Business Chronicle. GeoVax Developing Two Ebola Vaccines. Oct. 3, 2014.
 
37 CDC. Ebola (Ebola Virus Disease) Questions & Answers on Experimental Treatments and Vaccines for Ebola – Are there Ebola vaccines available for use or in development?. Accessed Oct. 14, 2014.
 

   



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