Ebola Virus [Ebola virus disease (EVD) or Ebola hemorrhagic fever (EHF) ]

What is Ebola?

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
  1. Unsterilized needles
  2. Suboptimal Hospital conditions
  3. 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.
        Muscle Pain.
        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

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