What is Ebola?
10/12/2014
What is Ebola?
Filoviridae
• Ebolavirus – 5 viruses/species
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Ebola (Zaire)
Sudan
Bundibugyo
Tai Forest
Reston
• Marburgvirus (single species)
• Cuevavirus
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Where Does it Come From?
• Not entirely clear, but likely fruit bats are
natural Ebola virus hosts
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Where Does it Come From?
• Bats may infect other animals
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Where Does it Come From?
• Any of these can infect humans
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Where Does it Come From?
• Once a human is infected, human-to-human
transmission occurs
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How are humans infected - 1?
• Infected fruit bats
– Bats have high titres in faeces
– Used as food
Bat soup: http://squathole.worldpress.com/
• Infected animals e.g. monkeys
– Handling uncooked bush meat
Bush meat:
http://www.telegraph.co.uk/news/worldnews/e
bola/11006343/Ebola-crisis-why-is-there-bushmeat-in-the-UK.html
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How are humans infected - 2?
• Human-to-human transmission
– Direct contact with blood or
secretions of infected people,
including urine, faeces, vomit, spit,
sweat, semen and breast milk
– Exposure to objects or environment
contaminated with infected
secretions
– Burial ceremonies through direct
contact with the body
• Access through mucosal surface /
breaks in skin / parenteral
(needlestick injury)
• Healthcare workers must practice
strict infection prevention and
control precautions
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Signs and Symptoms
• Signs generally begin 2-21 days
after contact with a person who
is sick with Ebola
– Most commonly 1-2 weeks,
average 11.4 days
• People infected with Ebola but
who do not show signs of
disease cannot spread the virus
Signs and Symptoms
• General: (0-3 days)
– Fever, headache, sore throat, chills,
weakness, tiredness
• Gastrointestinal symptoms: (3-10 days)
– Vomiting, diarrhoea, abdominal pain,
Hiccups
• Severe symptoms (7-12 days)
– Severe diarrhoea and vomiting, bleeding
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Other signs of Ebola Virus Disease
• Redness in the whites of the eyes
• Rash on the trunk
• Bleeding in 45% of cases (historically)
– Mild: nose bleed, bruising
– Severe: gastrointestinal bleeding, shock
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Timeline for how a person with Ebola
becomes more infectious over time
Source: Public Health England
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Ebola and infectivity
• Ebola virus is spread among people through:
– Touching body fluids of a person who is sick with or has died from Ebola
– Touching or using objects contaminated with Ebola
• People infected with Ebola can only spread the virus to
others once they have developed symptoms
• People with no or very mild symptoms (low-grade fever),
level of virus is low and unlikely to pose a risk to others
• Once a person is unwell, all body fluids are infectious, with
blood, vomit and diarrhoea being the most infectious
• Semen can remain infectious for up to three months after
recovery
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Clinical illness in first 106 patients with EVD,
Sierra Leone, May-June 2014 (n=106)
Schieffelin et al, NEJM, 29 Oct 2014
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What is the natural history of EVD in humans?
• Non-fatal cases
– Fever for 5-9 days and then improve
– Coincident with humoral antibody response
– Complete recovery can take weeks
• Weakness/ arthralgias/ headaches/ hair loss
• Deaths
– Mortality: 30-90%
– Current outbreak:
• Case fatality rate: 70%1
• Among hospitalised cases, deaths occur on average 4.2 days after
admission1
1 WHO
Ebola Response Team. Ebola Virus Disease in West Africa – the first 9 months of the epidemic and
forward projections. N Eng J Med 2014; 371:1481-95
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Ebola shares symptoms with many
diseases!
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•
•
•
Malaria
Typhoid fever
Cholera
Other viral hemorrhagic fevers (e.g., Lassa)
• Most people sick with fever, vomiting, and
diarrhea do not have Ebola
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Management of patients
Treatment and Vaccines
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Isolation
Ill patients require intensive supportive care
Fluids: oral rehydration if possible
No licensed vaccine available (several being tested)
No specific treatment available
New drug therapies being
evaluated
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Control in the population
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Acknowledgements
• Adapted from materials produced by:
– World Health Organisation (WHO)
– Centers for Disease Control and Prevention (CDC)
– Nigerian Centre for Disease Control and Prevention
– Public Health England
– Dr Todd F Hatchette, Nova Scotia, Canada
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More Information
• Health Protection Surveillance Centre
http://www.hpsc.ie/News/MainBody,14571,en.html
• CDC
http://www.cdc.gov/vhf/ebola/index.html
• WHO
http://www.who.int/csr/disease/ebola/en/
• HSE
http://www.hse.ie/eng/services/Campaigns/Ebolaupdate.html
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