Ebola is a virus which causes rare but deadly disease
Ebola virus disease (EVD) or Ebola
hemorrhagic fever (EHF)
which is a disease of humans and other primates. Symptoms start two days to
three weeks after contact with the virus. Symptoms area fever, sore throat, muscle
pain, and headaches. Typically nausea, vomiting, and diarrhea follow, along
with decreased functioning of the liver and kidneys. Around this time, affected
people may begin to bleed both within the body and externally.
Ebola’s natural reservoir is unknown.Non human primates have
been the source of human infections but are not thought to be the reservoirs.
Ebola Taxonomy or Scientific
Classification
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
Filoviridae or “Filoviruses”
•
Most
mysterious virus group
•
Pathogenesis
poorly understood
•
Ebola
–
Natural
history/reservoirs unknown
–
Exist
throughout the world
–
Endemic
to Africa
–
Filamentous
ssRNA- (antisense) viruses
History
Named after the Ebola River in the Democratic Republic of
the Congo (formerly Zaire), near the first epidemics.
Two species were identified in 1976:
- Zaire ebolavirus (ZEBOV)
- Sudan ebolavirus (SEBOV)
Case fatality rates of 83% and 54% respectively.
A third species, Reston ebolavirus (REBOV), was
discovered in November 1989 in a group of monkeys (Macaca fascicularis)
imported from the Philippines.
Ivory Coast ebolavirus – Only one case.
Unlucky scientist.
Outbreaks of EBOLA
Most Recent Incident
April 25 – June 16 2005 total of 12 cases including 9 deaths
were reported in Etoumbi and Mbomo in the Cuvette Quest Region
Ebola Pathogenesis
•
Enters Bloodstream
–
Skin,
membranes, Open wounds
•
Cell Level
–
Socks
with cell membrane
•
Viral RNA
–
Released into cytoplasm
–
Production new viral proteins/ genetic material
•
New viral
genomes
–
Rapidly coated in protein
–
Create cores
•
Viral cores
–
Stack up in cell
–
Migrate to the cell surface
–
Produce trans-membrane proteins
–
Push through cell surface
–
Become enveloped by cell membrane
•
ssRNA- Genome Mutations
–
Capable of rapid mutation
–
Very adaptable to evade host defenses and
environmental change
•
Theory
–
Virus
evolved to occupy special niches in the wild
Modes of
Transmission
There are 3 modes of infection
- Unsterilized needles
- Suboptimal Hospital conditions
- Personal contact
Symptoms and
Diagnostic Tests
•
Early symptoms
–
Muscle aches, fever, vomiting
–
Red eyes, skin rash, diarrhea, stomach pain
–
Acute symptoms
–
Bleeding/hemorrhaging from skin, orifices,
internal organs
–
Onset of fever.
–
Intense weakness.
–
Headache.
–
Soar Throat.
–
Vommitting, Diarrhoea.
–
Impaired Kidnay and liver function
•
Early Diagnosis
•
Very difficult
•
Signs & symptoms very similar to other
infections
•
Laboratory Test for the diagnosis of Ebola Virus
•
PCR detection
•
ELISA (enzyme-linked immuno-absorbant) assay
Is there a cure for
Ebola?
•
There are no known curative medications for
Ebola.
•
However, there have been very recent
developments in preventative medications.
•
No Standard Treatment available
•
Patients receive supportive therapy
•
Treating complicating infections
•
Balancing patient’s fluids and electrolytes
•
Maintaining oxygen status and blood pressure
•
No vaccines!
•
Patients are isolated
•
Medical Staff Training
•
Western sanitation practices
•
Intake
•
Care during stay
•
After patient dies
•
Infection-control Measures
•
complete equipment and area sterilization
Vaccines
•
In June, Jones and his colleagues, Dr. Heinz
Feldmann of Winnipeg and Dr. Thomas Geisbert at Fort Detrick, Maryland
announced that they had successfully vaccinated monkeys against the deadly
Ebola virus
•
The Ebola vaccine is based on the 1976 strain of
the Zaire species and protects from the 1995, but not the other 2 species that
affect humans.
Risk of Bioterrorism?
Airborne transmission of Ebola Zaire has been demonstrated
in monkeys in a controlled laboratory experiment
Plum Island…?
Prevention
After Death
Virus contagious in
fluids for days
•
Burial
use extreme caution
–
Handling
and transport
–
Cultural
practices/ religious belief
–
Incinerate
all waste!!!!
–
Protective
clothing
–
Body
sealed in body bag and coffin
–
Sanitation
of all equipment before and after
–
Risk for
exposure special steps need to be taken to protect the family and community
from illness.
–
Family
only
–
Why open
casket not possible
–
Some
practices cannot be done
Conclusion
•
Reservoirs
in Nature
–
Largely
unknown
–
Possibly
infected animals (primates?)
•
Transmission
–
Direct
contact blood/secretions of infected person
–
Possible
airborne (Reston primate facility)
•
Onset of
illness abrupt
–
Incubation
period: 2 to 21 days
–
Infections
are acute and mostly deadly
Latest Morbidity and
Mortality Reports
Ebola-Reston Virus Infection Among Quarantined Nonhuman Primates --
Texas, 1996
Report describes death and blood testing of cynomolgus monkey
imported from the Philippines held in a private quarantine facility in Texas
•
Outbreak of Ebola
Hemorrhagic Fever ---Uganda, August 2000--January 2001
–
Report describes
surveillance and control activities related to the EHF outbreak
–
Presents preliminary
clinical and epidemiologic findings
Ebola Information Posters
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