Transcript Document

Ebola: History
Dr Samuel Aguazim ( MD)
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History
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Ebola virus is part of the Filoviridae family,
which was first recognized in 1967 from an
outbreak that occurred in Germany and
Yugoslavia from imported Ugandan
monkeys.
Many of the people who were infected were
vaccine plant workers who came into direct
contact with the monkeys as they were being
used for polio vaccine production.
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Presentation
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Ebola and Marburg virus make up
the hemorrhagic fever viruses, with
Marburg virus demonstrating a more variable
pathogenicity.
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Ebola: Pathophysiology
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Ebola virus is a enveloped, nonsegmented,
negative-sense, single-stranded RNA
virus with a helical capsid. Along with
Marburg virus, they make up the virus family
Filoviridae, named for their thread-like
filamentous structure.
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Transmission
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Transmission of Ebola occurs mainly
through person-to-person contact with an
infected person’s bodily fluids such as blood,
vomit, urine, feces, and even sweat.
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Laboratory studies
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Laboratory studies have shown initiation of
infection can occur through ingestion,
inhalation, or compromised areas of skin.
Aerosolized forms have been shown to be
highly infectious in the laboratory setting, and
infection involving aerosols generated during
medical procedures have been documented.
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Natural reservoir
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The natural reservoir for Ebola, along with the
mode of transmission from reservoir to
primates, remains a mystery. Bats have
been suspected as being a non-primate
reservoir because of their presence in areas
during several outbreaks and isolation of
Marburg virus from fruit bats in Uganda.
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Natural reservoir
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Incubation period is usually about five to seven
days, but in some cases may exceed two weeks.
Once Ebola enters the body, the virus infects and
lyses endothelial cells, hepatocytes,
macrophages, and dendritic cells (antigenpresenting cells), releasing more particles into the
extracellular fluid. Viral particles spread to regional
lymph nodes, resulting in further rounds of
replication and dissemination to other lymphoid
tissues.
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Immunity
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Infection of macrophages and other cells
causes release of proinflammatory
mediators, cytokines, and chemokines,
which causes a systemic inflammatory
syndrome.
Impaired dendritic function and lymphocyte
apoptosis causes a decreased adaptive
immunity.
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Coagulation defects in Ebola virus infection
occurs indirectly through the synthesis of
tissue factor, which triggers the extrinsic
coagulation pathway. In addition, the
proinflammatory cytokines induce
macrophage production of tissue factor.
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Risk Factors
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Risk factors include recent travel to an
African region where Ebola virus outbreaks
have occurred, laboratory accident when
working with Ebola, or illness in a
healthcare worker during an epidemic in
Africa.
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Ebola: Clinical Manifestation
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Patients typically present with an abrupt
onset of fever greater than 38.6°C
(101.5°F), chills, and general malaise.
Other signs and symptoms can include
weakness, headache, myalgia, nausea,
vomiting, diarrhea, nonproductive cough,
pharyngitis, and abdominal pain. Bradycardia
can sometimes follow the high fever.
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Ebola: Clinical Manifestation
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Symptoms persist over a few days before
causing signs of hypotension, stupor, and
prostration. Coagulation defects usually
present as conjunctival hemorrhages, easy
bruising, and difficulty to clot after
venipuncture - contrary to the accounts of
“bleeding from all orifices.”
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Ebola: Clinical Manifestation
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Development of a non-pruritic
maculopapular rash on the upper
body during the first week of illness may be a
sign of an Ebola virus infection.
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Ebola: Clinical Manifestation
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Fatal outcomes associated with Ebola virus
usually occur due to severe intravascular
volume depletion, metabolic
abnormalities, and impaired oxygen
delivery.
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Ebola: Diagnosis and Treatment
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Diagnosis of Ebola virus infection involves
detection of viral antigens via enzyme-linked
immunosorbent assay (ELISA) or specific
RNA sequences by reverse-transcription
polymerase chain reaction (RT-PCR).
Sensitivity of these assays have not been
confirmed for individuals who are still
incubating the virus.
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Ebola: Diagnosis and Treatment
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Treatment of Ebola virus infection
is primarily supportive. Because
symptomatic manifestations of Ebola virus
infection are caused by the host response to
infection, supportive care is aimed at
maintaining cardiovascular function,
correction of coagulation defects, and any
other measures to maintain survival.
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Ebola: Diagnosis and Treatment
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There are currently no approved
therapies for patients infected with Ebola
virus. Evidence has shown improved survival
with a administration of monoclonal
antibody “cocktails.”
Recently, a combination of three monoclonal
antibodies (ZMapp) was used in the 2014
West African outbreak in two United States
health workers who developed Ebola virus.
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Ebola: Diagnosis and Treatment
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Several experimental strategies for post exposure prophylaxis
that have not been tested in humans are currently in
development that include
A live virus vaccine using recombinant vesicular stomatitis
virus (VSV) encoded with Ebola surface glycoproteins.
Small interfering RNAs and phosphorodiamidate morpholino
oligomers.
A synthetic small-molecule drug BCX4430 that inhibits viral
RNA polymerase function via RNA chain termination.
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Ebola: Diagnosis and Treatment
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There are currently no FDA approved
vaccines for Ebola.
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Ebola: Current Epidemic
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Researchers believe the sentinel case for the
2014 outbreak of Ebola virus was a 2-year-old
boy from a small Guinean village who fell ill in
December 2013.
The boy’s family all contracted the disease,
along with a health worker who carried it to
another village. From there the virus spread to
neighboring villages and by the end of May
2014, there were reported cases in Guinea,
Liberia, and Sierra Leone.
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Ebola: Current Epidemic
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As of August 12, 2014 there have been 1848
suspected and confirmed cases, and 1013
suspected case deaths.
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Ebola: Current Epidemic
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The current outbreak does not pose a significant
risk to the United States public, however agencies
such as the Center for Disease Control and
Prevention (CDC) is taking precautions within the
United States and internationally.
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Ebola: Current Epidemic
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The CDC is assisting with implementing exit
screening and communication efforts in West
Africa to prevent sick travelers and points of
entry and exit in the affected countries.
The CDC has activated its Emergency
Operations Center to help coordinate
technical assistance and disease control
activities with other organizations.
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Ebola: Current Epidemic
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The CDC has provided teams of public health
experts to the affected countries to assist with
a variety of response efforts.
The CDC is training United States healthcare
facilities on how to manage patients with
suspected Ebola virus infections.
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Double-Stranded RNA
Viruses
Lange Chapter 40 for rotavirus,
Chapter 42 for colorado tick fever
SAMUEL AGUAZIM M.D
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Family Reoviridae
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Non-Enveloped
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Both double-stranded (ds) RNA and doubleshelled icosahedral capsids. Segments( 1011)
Virion contains an RNA-dependent RNA
polymerase.
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Three Viruses in Family
Reoviridae
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Rotavirus
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Orbivirus
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Reovirus
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Rotavirus
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Major cause of infantile diarrhea worldwide
Fecal oral transmission ( common in
preschools and day care centers)
Vomiting and fever usually precede diarrhea
In healthy infants, illness lasts 3-9 days
The major serotype (A) causes diarrhea and dehydration
in infants <2 years, mild diarrhea in older kids, and
severe diarrhea , leading to death in malnourished
individuals.
This noninflammatory diarrhea is caused by protein
nsP4, a viral enterotoxin.
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Family Orbivirus: Colorado
tick fever virus
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Transmitted by the tick Dermacentor
andersoni
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One of the causes of viral encephalitis
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Camping and hiking in the Rocky Mountains
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Family Reovirus
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Asymptomatic common
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May also cause a febrile disease
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Chikungunya
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Chikungunya is most prevalent in West Africa and
presents with:
Fever
Polyarthralgia
Macular or maculopapular rash starting on the
limbs and trunk
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Astroviruses
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Astroviruses are non-enveloped RNA viruses
similar in size to polioviruses.
They have a characteristic five- or six-pointed
morphology.
These viruses cause watery diarrhea,
especially in children.
Most adults have antibodies against
Astroviruses, suggesting that infection occurs
commonly.
No antiviral drugs or preventive measures are
available.
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Japanese Encephalitis Virus
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Members of the flavivirus
Causes outbreaks of encephalitis in asian
countries.
Transmitted to humans by mosquitoes from
the reservior hosts, birds and pigs.
No antiviral therapy
An inactivated vaccine is available
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HUMAN T-CELL
LYMPHOTROPIC VIRUS
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Disease: adult t-cell leukemia/lymphoma and
HTLV associated myelopathy a.k.a tropical
spastic paraparesis or chronic progressive
myelopathy.
Characteristics- HTLV is a member of
retrovirus family. Causes malignant
transformation of CD4 positive T cells.
Transmission: IVDU, sexually, blood and
breast feeding.
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Lab DX: detect anti-HTLV antibodies in the
patients serum using ELISA.
WESTERN BLOT
PCR.
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Cache Valley Virus
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This virus was first isolated in Utah in 1956 but is
found throughout the western hemisphere.
It is a bunyavirus transmitted by Aedes,
Anopheles, or Culiseta mosquitoes from domestic
livestock to people.
It is a rare cause of encephalitis in humans.
There is no treatment or vaccine for Cache Valley
virus infections.
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Hendra Virus
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This virus was first recognized as a human
pathogen in 1994, when it caused severe
respiratory disease in Hendra, Australia.
It is a paramyxovirus resembling measles virus
and was previously called equine morbillivirus.
The human infections were acquired by contact
with infected horses, but fruit bats appear to be
the natural reservoir.
There is no treatment or vaccine for Hendra virus
infections.
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Human Metapneumovirus
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This paramyxovirus was first reported in 2001 as a
cause of severe bronchiolitis and pneumonia in
young children in the Netherlands.
It is similar to respiratory syncytial virus (also a
paramyxovirus) in the range of respiratory tract
disease it causes.
Serologic studies showed that most children have
been infected by 5 years of age and that this virus
has been present in the human population for at
least 50 years.
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Nipah Virus
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Nipah virus is a paramyxovirus that caused
encephalitis in Malaysia and Singapore in 1998
and 1999.
People who had contact with pigs were
particularly at risk for encephalitis caused by this
previously unrecognized virus.
There is no treatment or vaccine for Nipah virus
infections.
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Poxviruses of Animal Origin
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Four poxviruses cause disease in animals
and also cause pox like lesions in humans on
rare occasions.
They are transmitted by contact with the
infected animals, usually in an occupational
setting.
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Poxviruses of Animal Origin
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Cowpox virus causes vesicular lesions on
the udders of cows and can cause similar
lesions on the skin of persons who milk
cows.
Pseudocowpox virus causes a similar
picture but is antigenically distinct.
Orf virus is the cause of contagious pustular
dermatitis in sheep and of vesicular lesions
on the hands of sheepshearers.
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Monkey pox virus is different from the other
three; it causes a human disease that
resembles smallpox.
It occurs almost exclusively in Central Africa.
Any new case of smallpox like disease must be
precisely diagnosed to ensure that it is not due
to smallpox virus.
For these reasons, it is important to ensure that
new cases of smallpox like disease are due to
monkey pox virus
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Spumaviruses
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Spumaviruses are a subfamily of retroviruses
that cause a foamy appearance in cultured
cells. They can present a problem in the
production of viral vaccines if they
contaminate the cell cultures used to make
the vaccine.
There are no known human pathogens.
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Tacaribe Complex of Viruses
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The Tacaribe2 complex contains several human
pathogens, all of which cause hemorrhagic fever.
The best known are Sabia virus in Brazil, Junin
virus in Argentina, and Machupo virus in Bolivia.
Hemorrhagic fevers, as the name implies, are
characterized by fever and bleeding into the
gastrointestinal tract, skin, and other organs. The
bleeding is due to thrombocytopenia.
Transmission: food and water contaminated with
rodents excreta
Treatment: ribavarin
Prevention: no vaccine available
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whitewater arroyo virus
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This virus is the cause of a hemorrhagic
fever/acute respiratory distress syndrome in the
western part of the United States.
It is a member of the arenavirus family, as is Lassa
fever virus, a cause of hemorrhagic fever in Africa.
Wood rats are the reservoir of this virus, and it is
transmitted by inhalation of dried rat excrement.
This mode of transmission is the same as that of
the hantavirus, Sin Nombre virus (see page
There is no established antiviral therapy and there
is no vaccine.
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 BALANCE
BETWEEN
POWER AND
CHARACTER
 DETERMINE THE LEVEL
OF SUCCESS YOU
ENJOY….
 DRS
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