This document summarizes key information about the Ebola virus. It describes Ebola as an enveloped RNA virus that originated in Africa and is typically transmitted between humans through direct contact with bodily fluids of infected individuals. While fruit bats are believed to be the natural reservoir, humans can also contract the virus through contact with infected wildlife. The virus causes severe disease by directly infecting tissues and triggering immune dysregulation, hypovolemia, coagulopathy, and ultimately multi-organ failure. Mortality rates are high, ranging from 25-90% depending on the strain.

1. EBOLA: The Virus
Dr Sandeep Dogra
MD, MNAMS
Assistant Professor
Dept. of Microbiology
Govt. Medical College, Jammu

2. Outbreak anywhere can be a risk everywhere
- Thomas R Frieden, CDC, Atlanta, USA

3. Overview
• The agent
• Taxonomy
• Reservoir
• Transmission
• Pathogenesis

4. The agent
• Enveloped, non-segmented,
negative-stranded RNA virus
• Prototype Viral Hemorrhagic
Fever Pathogen
• First appeared in 1976 in 2
outbreaks
• Derived it’s name from a river
in Congo called Ebola
• Caused more than 20 outbreaks
in Africa since than

6. Taxonomy
• Order: Mononegavirales
• Family: Filoviridae
• Genus: Ebola like viruses
• Species: Ebola
• Subtypes:
▫ Zaire Ebola virus - Democratic Republic of Congo (1976)
▫ Sudan Ebola virus - Sudan (1976)
▫ Reston Ebola virus - Philippines (1989)
▫ Tai Forest Ebola virus - Ivory Coast (1994)
▫ Bundibugyo Ebola virus - Uganda (2007)
C.M. Fauquet (2005). Virus taxonomy classification and nomenclature of viruses;
8th report of the International Committee on Taxonomy of Viruses

7. Reservoir of infection
• Zoonotic virus
• Fruit bats - most likely reservoir
▫ Hypsignathus monstrosus
▫ Epomops franqueti
▫ Myonycteris torquata
• Others - Chimpanzees, gorillas,
monkeys, forest antelope and
porcupines
• Limited evidence that wild
dogs/cats become infected

9. Transmission
• In Africa, Ebola may spread as a result of
hunting, processing, and consuming infected
animals (e.g., bush meat)
• Human-to-human transmission of Ebola virus
via inhalation (aerosols) has NOT been
demonstrated
• Remains from deceased infected persons are
highly infectious
• Close contact and health care workers get
frequently infected while treating the patient

11. Human to human transmission
• Virus present in high quantity in blood, body fluids,
and excreta of symptomatic patients
• Opportunities for human-to-human transmission
▫ Direct contact (through broken skin or unprotected
mucous membranes) with an EVD-infected patient’s
blood or body fluids
▫ Direct contact with the corpse of a person who died
of EVD
▫ Sharps injury (with EVD-contaminated needle or
other sharp)
▫ Indirect contact with an EVD-infected patient’s
blood or body fluids via a contaminated object (soiled
linens or used utensils)

13. Pathogenesis
• Incubation period ranges between 2-21 days
• Onset of symptoms to death: 6-16 days
• Mortality rates: 25-90% depends on Ebola strain
• Zaire strain most virulent - mortality up to 90%
• People are infectious as long as their blood and
secretions contain the virus
WHO. Ebola virus disease. Fact Sheet No. 103. Geneva: World Health Organisation, 2014.

14. Pathogenesis
• Molecular basis of virulence not known
• Direct infection of tissues
• Immune dysregulation
• Hypovolemia and vascular collapse
▫ Electrolyte abnormalities
▫ Multi-organ failure, septic shock
• Disseminated intravascular coagulation (DIC)
and coagulopathy
Lancet. Mar 5, 2011; 377(9768): 849–862.

15. Direct infection of tissues
• Infects many cell, including monocytes,
macrophages, dendritic cells, endothelial cells,
fibroblasts, hepatocytes, adrenal cortical cells
and epithelial cells.
• Virus migrates from the initial infection site to
regional lymph nodes and subsequently to the
liver, spleen and adrenal gland.

16. Immune dysregulation
• High mortality rate believed to be the result of
virus proteins capability of defeating the
immune system by:
▫ Complement mediated antibody-dependent
enhancement of infection
▫ Inhibition of multiple interferon pathways
▫ Infected macrophages inducing apoptosis in
lymphocytes

17. Hypovolemia and DIC
• Adrenocortical necrosis also occurs and is
associated with hypotension and impaired
steroid synthesis
• Hepatocellular necrosis leads to dysregulation of
clotting factors and subsequent coagulopathy
• Virus appears to trigger a release of pro-inflammatory
cytokines with subsequent
vascular leak and impairment of clotting
ultimately resulting in multi-organ failure and
shock .

18. Philippe Calain
Chief Epidemiologist
CDC Special Pathogens Branch
"At the end of the disease the patient does not look, from
the outside, as horrible as you can read in some books.
They are not melting. They are not full of blood. They're
in shock, muscular shock. They are not unconscious, but
you would say 'obtunded', dull, quiet, very tired. Very
few were hemorrhaging. Hemorrhage is not the main
symptom. Less than half of the patients had some kind
of hemorrhage. But the ones that had bled, died"

19. Summary
• Humans are actually just an accidental host
• Human-to-human transmission by direct
contact
▫ No human-to-human transmission via inhalation
(aerosols)
▫ No transmission before symptom onset
• Greater risk for India because of the number of
Indians working in West African nations
• Constantly changing genetic makeup of the
Ebola virus means it will spread at a much
greater speed.

20. More information…
www.cdc.gov www.who.int

21. Thank you Ebola
For making us realize that how much we interfere with nature and
how much we are prepared for any eventuality.