2014 Ebola Virus Outbreak. What is a Virus? Viruses are microscopic particles (10 – 400 nm)....
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2014 Ebola Virus Outbreak. What is a Virus? Viruses are microscopic particles (10 – 400 nm). Viruses are made of genetic material (DNA or RNA) surrounded
What is a Virus? Viruses are microscopic particles (10 400 nm).
Viruses are made of genetic material (DNA or RNA) surrounded by a
protein coating and sometimes an outer layer containing lipids.
Viruses are not made of cells. Viruses must infect cells to make
more copies of themselves. A virus cannot reproduce without
infecting a cell and using the components of a host cell to make
more copies of itself. The new virus particles then infect other
cells to continue to make more virus particles. Antibiotics are not
effective against viruses.
Slide 3
What is Ebola Virus? Ebola virus is a member of a family of
viruses called Filoviridae. Ebola virus particles form long
filaments. The virus particles contain single-stranded RNA
surrounded a lipid (fatty) membrane. The new virus particles bud
from the surface of the host cell. Ebola virus was first discovered
in 1976 near the Ebola River in Zaire (now the Democratic Republic
of Congo). There are four species of Ebola virus that cause disease
in humans. The one causing the outbreak is a strain of the Zaire
species. Credit: NIAID
Slide 4
What is Ebola Virus Disease? The disease caused by Ebola virus
is called Ebola Virus Disease (EVD). Ebola Virus Disease is
considered a hemorrhagic fever disease, a type of disease caused by
Ebola and other viruses that is characterized by bleeding and
fever. The symptoms of EVD include Fever Headache Vomiting Diarrhea
stomach pain muscle pain bleeding Credit: Wikimedia Commons
Slide 5
It is not easy to catch Ebola virus. An infected person is
contagious only while they have symptoms. To become infected, a
person must have direct contact with blood or another body fluid,
such as feces or vomit, from an infected person, or with an object
that is contaminated with infected body fluids. Following contact,
the virus must enter an opening in the body, like a break in the
skin or the eyes, nose, or mouth. Ebola virus does not spread
through the air, unlike flu. In Africa, some people have become
infected by handling bushmeat or through contact with infected
bats. Family members or healthcare workers are at highest risk of
becoming infected. How do you get Ebola?
Slide 6
How does Ebola make you sick? Ebola virus infects certain cells
of the immune system, so that they do not function properly.
Instead of protecting a person from infection, they produce
chemicals that cause harm. Ebola virus also infects endothelial
cells which line blood vessels. Blood leaks out of damaged blood
vessels. Patients develop very low blood pressures and go into
shock. Patients usually die from shock due to fluid loss rather
than actual blood loss. Between 25 and 90 percent of patients with
EVD die of the disease. In the current outbreak, slightly less than
half of Ebola victims survive. Credit: CDC
Slide 7
There is no cure for EVD. There is no licensed vaccine for EVD.
There are experimental drugs and vaccines, but they have not been
tested in humans, so it is not known how effective or safe they
are. The supply of experimental drugs is very limited, so there is
an ethical dilemma regarding who should receive the drugs. A few
patients are receiving blood plasma from patients who have
recovered from Ebola infection that contains antibodies to Ebola.
Patients in hospitals are given supportive care to maintain body
fluids, salt levels, and blood pressure. This improves survival
rates. What is the treatment for EVD? Credit: NIAID
Slide 8
Where does Ebola come from? Many viruses that infect humans
emerged from animals. A virus can be present in a host animal and
not make them ill, but the virus can be passed to another animal or
a person and make them sick. The natural host of Ebola virus is
thought to be the fruit bat, which in found in regions of Africa
where outbreaks have occurred. The first person in an outbreak
becomes infected through contact with an infected animal. The virus
can then spread from person to person. Credit: WHO
Slide 9
Why is EVD called an emerging disease? EVD is considered an
emerging infectious disease. An emerging infectious disease is one
that has recently been detected, or a known one that has appeared
in a new place, or one that is spreading rapidly. Emerging
infections can be caused by previously unknown viruses (or other
infectious agents such as bacteria) or viruses that spread to new
locations. Other examples of emerging viruses are SARS, MERS, flu,
HIV, and Chikungunya virus. Credit: NIAID Credit: CDC
Slide 10
When and where was Ebola discovered? Credit: CDC Ebola was
first recognized in 1976 when it caused two separate outbreaks one
in Zaire (now the Democratic Republic of Congo) and the other in
southern Sudan. The outbreaks were caused by different species. The
Zaire virus caused deaths in 90% of infected people; the Sudan
virus caused deaths in 50%. Since then, there have been about 20
outbreaks of Ebola in central Africa with a total of around 2400
cases and 1600 deaths. Because the prior outbreaks occurred in
remote areas, they were easier to contain. Credit: Wikimedia
Commons
Slide 11
How did the current outbreak begin? The first person to become
infected was a two year old boy living in Guinea in December 2013.
The Ebola outbreak was officially recognized in March 2014 in
Guinea and then quickly spread to Liberia and Sierra Leone. There
have been a small number of cases in Nigeria, Senegal, and Mali,
but almost all cases have been in Liberia, Guinea, and Sierra
Leone. Ebola transmission has stabilized in Liberia and Guinea, but
remains intense in Sierra Leone. By the beginning of December,
there have been in total more than 17,000 cases and 6,000
deaths.
Slide 12
Credit: Wikimedia Commons Map showing case numbers in West
Africa The most cases and deaths have occurred in Liberia, followed
by Sierra Leone, and then Guinea. The rate of new infections is
slowing in Liberia and Guinea but still increasing in Sierra
Leone.
Slide 13
How did Ebola spread to the U.S.? Ebola spread to the United
States when a Liberian man who had contact with an Ebola victim
flew to Dallas, Texas. He developed symptoms after arriving in the
U.S. The hospital did not recognize his illness as Ebola and sent
him home. He returned three days later, was admitted to the
hospital, and died ten days later. A nurse who treated this patient
tested positive for the virus. This was the first transmission
within the U.S. A second nurse was also diagnosed with Ebola. Both
nurses recovered. No further transmission occurred. A few patients
who became infected in West Africa have been treated in several
locations in the United States and Europe. In one case, a
healthcare worker became infected in Spain, but no other new
infections occurred.
Slide 14
Why is this outbreak so bad? It started near the borders of
three countries where there is a lot of travel. It started in
countries where Ebola had not been seen before, so it had a chance
to spread before it was recognized. It went into very densely
populated cities where the virus could spread easily. It began in
countries with weak healthcare systems that did not have enough
hospital beds or isolation equipment, and many healthcare workers
became ill and died. Response from governments and other agencies
was too slow. It spread to new countries by air travel. Credit:
CDC
Slide 15
How will the outbreak be stopped? Tracing of all people who had
close contact with an infected person while they were showing
symptoms Isolation of all infected people with symptoms Improved
personal safety procedures and training for healthcare workers and
complete compliance with these safety procedures Implementation of
safe burial procedures Production of drugs and vaccines Containment
of the Ebola outbreak in West Africa to prevent further spread to
other countries Learning from this outbreak how to limit future
outbreaks of Ebola or other emerging viruses Credit: CDC