Description about recent outbreak of Ebola virus in West African countries with history, pathogenesis, clinical signs and prevention measures of Filoviruses are presented in comprehensive manner.

1. Marburg and Ebola viruses
Lethal beyond imagination!!!!!!!
PANKAJ DHAKA
Ph.D Scholar, VPH, I.V.R.I
pankaj.dhaka2@gmail.com

2. Taxonomy
Order: Mononegavirales
Family: Filoviridae
Genus: Ebola like viruses
Species: Ebola
Subtypes
– Ebola-Zaire, Ebola-Sudan,
Ebola-Ivory Coast
• disease in humans
– Ebola-Reston
• disease in nonhuman primates

3. The Media and Public Perception

5. Ebola outbreak- 2014
• World's worst outbreak of the Ebola virus, killing 3,338 people
…..and continue…
• Location: West Africa, caused by the Zaire species of the virus
• Although most previous Ebola outbreaks occurred in Central
Africa, this outbreak started in the West African nation of
Guinea in late 2013
• “On 8 August 2014, the WHO declared the epidemic to be an
international public health emergency”

6. • General concepts- Ebola and Marburg viruses are
– Non-segmented
– Negative-sense
– ss RNA viruses that resemble rhabdoviruses and paramyxoviruses in
their genome organization and replication mechanisms
– Together, they make up the family Filoviridae.
• Latin "filum," meaning thread-like, based upon their
filamentous structure
• Also classified as "hemorrhagic fever viruses" based on their
clinical manifestations, which include coagulation defects, a
capillary leak syndrome, and shock [Bray, 2005]
An Introduction

7. Viral structure:
• Mature filoviral particles take on a variety of forms from circular or
“6”-shaped to straight filaments
• Length of the virions is variable with Marburg particles averaging
close to 800 nm, and Ebola virions measuring about 1 μm
• The diameter of all filovirus particles uniformly measures- 80 nm.

8. Marburg virus
• All isolates of Marburg virus are currently considered to be
members of a single species
– First outbreak (Marburg, Germany, 1967)
– laboratory workers infected by monkeys
• They may vary in their pathogenicity for humans
• Overall fatality rate in the 1967 outbreak in Europe was 21 %,
whereas mortality among identified cases in 2000 in the Democratic
Republic of Congo (DRC) and in 2005 in Angola was in the range
of 80-90%
• Alternatively, the striking difference in outcome may reflect the
paucity of medical resources where the latter outbreaks took place
[Bausch et. Al., 2003]
(African Hemorrhagic Fever, Green Monkey Disease, Marburg Fever)

9. The name ‘Ebola’
Aug 26, 1976 in Yambuku, town of Zaïre
-44 year-old school teacher, went to the doctor
for his high fever, they gave him a quinine shot
which is good against malaria
-A week later, uncontrolled vomiting, bloody
diarrhea, trouble breathing and then bleeding
from his nose, mouth, and anus
-He died ~14 days after the onset of symptoms
He started an epidemic that killed 280 of
the 313 infected persons (88%)
& still To be continued to ….the
deadliest outbreak of Ebola in history

10. A glimpse of Ebola virus assault:
• Five species- Zaire, Sudan, Ivory Coast, Bundibugyo &
Reston
• The Zaire virus: 1st appearance in 1976, caused multiple
large outbreaks with mortality rates of 55 to 88 %
• The Sudan virus: 50 % case-fatality rate in four known
epidemics: two in Sudan in the 1970s, one in Uganda in
2000, and Sudan in 2004.
• The Ivory Coast virus: Identified as the causative agent
in an ethologist performed a necropsy on a chimpanzee in
the Tai Forest. The case survived
• The Bundibugyo virus: Emerged in Uganda in 2007,
lower case-fatality rate (30%)
• The Reston virus: Apparently maintained in an animal
reservoir in the Philippines , not been found in Africa.
• 1st recognized in an outbreak of lethal infection in
macaques imported into the U.S in 1989. This episode
brought the filoviruses to worldwide attention through the
publication of Richard Preston's book, The Hot Zone.

11. Major outbreaks:
2014

12. Death toll of Ebola…..

13. RNA
L
NP
VP35
VP40 VP30
Membrane
VP24
GP1,2
?
Molecular Biology
OR
GP VP30
IRIR
VP40
3‘-HO
NP VP35
IR
l
IR1
IR
t
19,104
P -5‘
LVP24
The virions contain the ~ 19 kb non-infectious genome that encodes seven structural
proteins with a gene order of: 3' leader, nucleoprotein (NP), virion protein (VP) 35
(VP35), VP40, glycoprotein (GP), VP30, VP24, polymerase L protein, and 5' trailer.

14. Pathogenesis of Ebola and Marburg virus infection

15. Impairment of adaptive immunity
Through impaired dendritic cell function and lymphocyte apoptosis
• Act both directly and indirectly to disable antigen-specific immune responses
– Dendritic cells, which have primary responsibility for the initiation of adaptive immune responses, are
a major site of filoviral replication.
– Infected cells fail to undergo maturation and are unable to present antigens to naive lymphocytes-
Explaining why patients dying from Ebola hemorrhagic fever do not develop antibodies to the virus
• Adaptive immunity is also impaired by the massive loss of lymphocytes that
accompanies lethal Ebola virus infection.
– Lymphocytes remain uninfected, but undergo "bystander" apoptosis, presumably induced by
inflammatory mediators and/or the loss of support signals from dendritic cells, resembles
phenomenon of septic shock
(Geisbert et. al., 2003)
The infections are characterized by “crashing” patients with liquefying organs; patients
die from extensive blood loss

16. How it works
Threadlike Ebola virions bud from a
cell, Ebola virus disables a cell's
tetherin protein.
Tetherin: A human cellular protein
which inhibits retrovirus infection by
preventing the diffusion of virus
particles after budding from infected
cells

18. PATHOGENESIS
• Endothelial cells, phagocytes and hepatocytes are main target of the
infection.
• After infection a secreted glycoprotien (sGP) is synthesized.
• sGP forms the trimeric complex, which binds the virus to
endothelial cell. Also inhibits the early steps of neutrophil
activation.
• The presence of viral particles and cell damage resulting from
budding leads to release of cytokines TNF , IL-6 and IL-8.The
cytopathic effect from infection in endothelial cells result in loss of
vascular integrity (Onyango et. al., 2007)

19. Where does Ebola hide?
• 2002- Fruit Bats showed
antibodies against Ebola
• Isolated from liver and
spleen
• Fruit bats do not show any
symptoms, hence best
candidate to be the
reservoir
• More research needs to be
done

20. Towards detecting the natural host of the virus

21. Ecology of virus

22. The virus kills gorillas and chimpanzees and other monkeys. in such high
percentage – they are not likely to be its natural host

23. TRANSMISSION:
• Close contact with blood, secretion, organs
or other body fluid of infected animals
• Handling of infected monkeys, chimpanzees
& fruit bats
• Human to human transmission- vomiting
from direct contact with the blood, secretion,
organs or body fluid like saliva or semen
• Burial ceremonies in which mourners have
direct contact with the body of deceased
person can play role in transmission
• It can spread through semen for up to
7weeks after recovery from illness

24. Clinical symptoms:
• I.P: 2-21 days
• Abrupt illness with fever, severe frontal
headache, red eyes, malaise, lumbar
myalgia, vomiting, nausea and diarrhoea.
• Maculopapular rash begins 5-7 days later
on trunk and upper arms.
• GI haemorrhage as the severity of illness
increases.
• Marked leucopenia, necrosis of
granulocytes, DIC and thrombocytopenia
• In fatal case patient become
hypotensive, develop impaired liver and
kidney functions and lapse into coma.

25. DIAGNOSIS:
• Ruled out- malaria, typhoid, shigellosis,
cholera, leptospirosis, plague, rickettsia,
relapsing fever, meningitis, hepatitis and
other viral hemorrhagic fever
• If there is strong suspicion and reason to
consider Ebola HF, patient should be
isolated & following that samples
should be collected and tested to
confirm
• Diagnostic test available are:
– Antigen Capture ELISA
– Antibody capture ELISA (IgM & IgG)
– RT PCR Assay
– Virus isolation & immunohistochemistry
testing

26. TREATMENT:
• No specific treatment is available, supportive
management can be done
• Therapeutic principle: Reversal of dehydration,
hemoconcentration, renal failure, protein,
electrolyte loss or blood loss
• Transfusion of fresh blood & platelets are
frequently given to combat DIC &
haemmorhagic manifestation. Successful
management may require renal dialysis.
• Drug Zmapp: Like i/v immunoglobulin therapy,
ZMapp contains neutralizing antibodies that
provide passive immunity to the virus by
directly and specifically reacting with it in a
"lock and key" fashion, experimental treatment
was used in humans in present outbreak.

27. Preventive measures during epidemic
• Hospitalization and Isolation
of patients
• Quarantine areas if Necessary
• Protective measures (Gloves,
gowns, face shields, masks,
eye Protection)
• Disinfect bedding, utensils,
excreta (heat or chemicals)
• Burn used articles

28. Isolation Criteria
Based upon 4 main factors:
1. Potential harm to life
2. Potential harm to critical systems
3. Potential harm to property
4.Topography & meteorological
considerations
 Direct Contact with infected
blood, body fluids to be avoided
Airborne transmission rare, but
cannot be conclusively excluded-
negative pressure room and HEPA
respirator
Laboratory Precautions- BSL 4
Personal Protective Equipment
Post-Mortem Practices
Protection tips for authority:

29. Challenges:
• Finding the Reservoir
• How different strains with different
mortility!!!!1
• Need to know more about Transmission
– From animal to man
– Ways of putting it into food
• Aerosolization
– Possible ???

30. Bioweapon !!!!!
– Rates of fatality
– Deaths
• Terror of dying
• Ignorance of the general public
– Think that they can die by being in same room with
person
– Much not known by general physicians and scientist

31. “Adopt the pace of nature: her secret is patience” - R. Emerson