Ebola Virus Disease (EVD)
Dr. Rizwan S A, M.D.,Department of Community Medicine,VMCH&RI, Madurai,
“Got no time for wild polemics, hung up on epidemics” – Anonymous
Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
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Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Rizwan SA, VMCHRI
Why learn about EVD?
Limited scientific understanding
Highly fatal disease
Causes large outbreaks
Difficult to contain
No proven treatment or vaccine
A pandemic threat
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Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Rizwan SA, VMCHRI
A story – 1/3
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A story – 2/3
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A story – 3/3
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Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Rizwan SA, VMCHRI
Epidemiological aspects
Natural host - Fruit bats of Pteropodidae family
Reservoir – fruit bats
Sources – bush meat, NHP, Infected humans, fomites
Incubation period – 2 to 21 days
Communicability – high, virus isolated after 90 days of recovery
Case fatality – 50 to 90%
Immunity – long term not proven, deceased patients failed to produce immune response
No. of outbreaks – >30
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Geographic distribution – 1/2
First outbreak occurred in Zaire (Congo) in 1976
Followed by several outbreaks, all in Africa (except one in Philippines, Italy, USA)
Latest on-going outbreak in west Africa started in March 2014 in Guinea
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Geographic distribution – 2/2
Rizwan SA, VMCHRI
Modes of transmission
Direct contact (through broken skin or mucous membranes) with a sick person's blood or body fluids (urine, saliva, faeces,
vomit, semen) objects (such as needles) that have been contaminated with
infected body fluids infected animals
High risk groups – bush meat hunters, forest dwellers, health workers, relatives of patients, funeral attendees, corpse handlers, lab personnel
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Transmission cycle
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Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Virological aspects
• Family Filoviridae in the order Mononegavirales
• Five species• Zaire, Sudan, Taï, Reston,
Bundibugyo
• Enveloped, non-segmented, negative-strand RNA virus, filamentous
• Genes arranged linearly coding for seven structural proteins - NP, VP35, VP40, GP, VP30, VP24 and L with NP
• GP, transmembrane protein and responsible for receptor binding and membrane fusion
Rizwan SA, VMCHRI
Clinical features• Range from minor viral illness
to fatal haemorrhagic fever • Ebola haemorrhagic fever
(Ebola HF) is type of Viral Haemorrhagic Fevers
• Most common constellation of symptoms is together called Ebola Virus Disease
• EVD – duration 2 to 20 days, fever, nausea, vomiting, non-bloody diarrhoea, abdominal pain, conjunctivitis, weakness, severe headache and myalgia
• E. Hemorrhagic fever - hematemesis, epistaxis, increased postpartum bleeding, bleeding gums etc.,
Rizwan SA, VMCHRI
Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Rizwan SA, VMCHRI
Diagnosis
CDC case definitions Person Under Investigation Probable case Confirmed case Non-case Exposure risk levels
• In early phase - Antigen-capture ELISA, IgM ELISA, PCR, Virus isolation
• In later phase - IgM and IgG antibodies
• In deceased patients – immunohistochemistry, PCR, virus isolation
• Strict precautions during transportation of samples and all testing in BSL-4 lab
• Differentials – Lassa fever, malaria, shigellosis, cholera, leptospirosis, plague, rickettsiosis, relapsing fever, other viral haemorrhagic fevers
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Treatment Experimental treatments
ZMapp – a combo of 3 monoclonal antibodies
TKM-Ebola – targets RNA of the virus
MB-2003 - prevents infection in mice and non-human primates when administered as post-exposure prophylaxis within one to two days
BCX-4430 – RNA polymerase inh
Favipiravir, AVI 7288
Whole blood and convalescent serum transfusion from recovered patients
• No proven antiviral drug • Symptomatic treatment only• Providing intravenous fluids
and balancing electrolytes (body salts)
• Maintaining oxygen status and blood pressure
• Treating other infections if they occur
• Barrier-nursing techniques• Personal Protective
Equipment • Infection control measures• Isolation of Ebola patients
from contact
Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Control measures – 1/5
Public health measures - early detection and isolation, contact tracing and rigorous infection control measures
Screening of travellers from affected countries in airports, seaports and land borders
Quarantine and observation of suspected cases for 21 days from exposure
Awareness generation among people, removing misconceptions
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Control measures – 2/5
All suspected or confirmed cases, single closed patient room
Avoiding contact
A log book containing details of persons entering
Personal protective equipment for caretakers
Dedicated medical equipment
Minimum use of sharps
Disinfection of samples - heating to 60°C for one hour, in 3% acetic acid
Only BSL 4 lab should handle samples
Hospital monitoring policy for staff
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Control measures – 3/5
Vaccines Virus like particles: ZEBOV (VP40, CG and NP)
Non-replicating vectors: alpha virus, DNA vaccines, recombinant adenovirus based
vectors (rAD)
Replication competent vectors: Recombinant Paramyxovirus-based vectors,
Recombinant vesicular stomatitis virus-based vectors (rVSV), Recombinant rabies
virus based (rRABV)
The first vaccine platform that successfully protected NHPs from Ebola virus infection
was a recombinant adenovirus serotype 5(rAd5) vector
Latest - chimpanzee-derived replication-defective adenovirus (ChAd) vaccine
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Control measures – 4/5
Social aspects Cultural practices – burial rituals Illiteracy and lack of awareness Fear of modern medicine, equipment False rumours and misinformation Ethical issues of giving experimental treatment
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Control measures – 5/5
International cooperation CDC, WHO, European Mobile Laboratory (EMLab) Project,
African Union
Voluntary agencies - MSF, Samaritan’s Purse
Staff, Outbreak response teams, lab experts, doctors, equipment, gloves, medicines, disinfectants
Research for medicines and vaccines
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Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Rizwan SA, VMCHRI
Challenges to control
Lack of effective treatment and vaccine
Weak public health infrastructure, manpower, weak labs
Poverty and Illiteracy
Lack of political stability
Delayed international response
Failure to anticipate and incorporate social aspects
Funding problems
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Rizwan SA, VMCHRI
Outline
Why learn about EVD?
History
Epidemiology
Virological and clinical aspects
Management
Control measures
Challenges
Pandemic threat
Rizwan SA, VMCHRI
Pandemic threat
None of the past outbreaks have developed into a pandemic
But,
2014 outbreak – As of August 31, 2014, 3707 cases and >1800 people dead across 5 countries
WHO’s declared ‘Public Health Emergency of International Concern’ in August 2014
Attack rate - 12.6 cases per 10,000 inhabitants, Ro is 2.7
No population level immunity
Bioterrorism32/35
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Take home messages
Ebola is an new and emerging infection
Ability to cause large outbreaks with high casualty
In the absence of proven treatments, prevention is the main weapon
Social aspects are very important in control
Simple and established PH measures are sufficient
A potential pandemic
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Home work
Group 1 - Learn the principles of outbreak investigation – watch the movie ‘Contagion’ and write a one page summary
Group 2 - A one page summary on conditions needed to declare a pandemic
Group 3 - A one page summary of how India is planning to respond to this threat, the agencies involved and your ideas for preparedness in our hospital
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Rizwan SA, VMCHRI
Reference materials
CDC website http://www.cdc.gov/vhf/ebola/about.html
WHO website http://www.who.int/csr/disease/ebola/en/
The Lancet Ebola Resource Centre http://ebola.thelancet.com/
Journals - Bulletin of the WHO, NEJM and BMJ, August and September 2014 issues
Image courtesy – bbc.co.uk, google images, CDC and WHO
Thank You
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