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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
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Ebola virus disease/ Ebola outbreak

Nov 12, 2014

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Health & Medicine

Rizwan S A

A comprehensive yet crisp primer on Ebola virus and its public health relevance.
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Page 1: Ebola virus disease/ Ebola outbreak

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

Page 2: Ebola virus disease/ Ebola outbreak

Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

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Page 3: Ebola virus disease/ Ebola outbreak

Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

Page 4: Ebola virus disease/ Ebola outbreak

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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Page 5: Ebola virus disease/ Ebola outbreak

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

A story – 1/3

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A story – 2/3

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A story – 3/3

Rizwan SA, VMCHRI 8/35

Page 9: Ebola virus disease/ Ebola outbreak

Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

Page 10: Ebola virus disease/ Ebola outbreak

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

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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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Page 14: Ebola virus disease/ Ebola outbreak

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Transmission cycle

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Page 15: Ebola virus disease/ Ebola outbreak

Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

Page 16: Ebola virus disease/ Ebola outbreak

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

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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

Page 18: Ebola virus disease/ Ebola outbreak

Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

Page 19: Ebola virus disease/ Ebola outbreak

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

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Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

Page 22: Ebola virus disease/ Ebola outbreak

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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Page 27: Ebola virus disease/ Ebola outbreak

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

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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Page 29: Ebola virus disease/ Ebola outbreak

Rizwan SA, VMCHRI

Outline

Why learn about EVD?

History

Epidemiology

Virological and clinical aspects

Management

Control measures

Challenges

Pandemic threat

Page 30: Ebola virus disease/ Ebola outbreak

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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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

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Thank You