Where does the disease come from?
Ebola was first discovered in 1976, and it was once thought
to originate in gorillas, because human outbreaks began after people ate
gorilla meat. But scientists have since ruled out that theory, partly because
apes that become infected are even more likely to die than humans.
Scientists now believe that bats are the natural reservoir for the virus, and that apes and humans catch it from eating food that bats have drooled or defecated on, or by coming in contact with surfaces covered in infected bat droppings and then touching their eyes or mouths.
The current outbreak seems to have started in a village near Guéckédou, Guinea, where bat hunting is common, according to Doctors Without Borders.
Scientists now believe that bats are the natural reservoir for the virus, and that apes and humans catch it from eating food that bats have drooled or defecated on, or by coming in contact with surfaces covered in infected bat droppings and then touching their eyes or mouths.
The current outbreak seems to have started in a village near Guéckédou, Guinea, where bat hunting is common, according to Doctors Without Borders.
How does the disease progress?
Symptoms usually appear about eight to 10 days after exposure, according to the Centers for Disease Control and Prevention.
At first, it seems much like the flu: a headache, fever and aches and pains.
Sometimes there is also a rash. Diarrhea and vomiting follow.
Then, in about half of the cases, Ebola takes a severe turn, causing victims to hemorrhage. They may vomit blood or pass it in urine, or bleed under the skin or from their eyes or mouths. But bleeding is not usually what kills patients. Rather, blood vessels deep in the body begin leaking fluid, causing blood pressure to plummet so low that the heart, kidneys, liver and other organs begin to fail.
Then, in about half of the cases, Ebola takes a severe turn, causing victims to hemorrhage. They may vomit blood or pass it in urine, or bleed under the skin or from their eyes or mouths. But bleeding is not usually what kills patients. Rather, blood vessels deep in the body begin leaking fluid, causing blood pressure to plummet so low that the heart, kidneys, liver and other organs begin to fail.
How is the disease treated?
There is no vaccine or definitive cure for Ebola, and in past
outbreaks the virus has been fatal in 60 to 90 percent of cases. The United
States government plans to fast-track development of a vaccine shown to
protect macaque monkeys, but there is no guarantee it will be effective in
humans. The question of who should have access to the scarce supplies of an
experimental medicine has become a hotly debated ethical
question. Beyond this, all physicians can do is try to nurse people through the
illness, using fluids and medicines to maintain blood pressure, and treat other
infections that often strike their weakened bodies. A small percentage of
people appear to have an immunity to the Ebola virus.
How contagious is the virus?
You are not likely to catch Ebola just by being in proximity with
someone who has the virus; it is not airborne, like the flu or respiratory
viruses such as SARS.
Instead, Ebola spreads through direct contact with bodily fluids. If an infected person’s blood or vomit gets in another person’s eyes, nose or mouth, the infection may be transmitted. In the current outbreak, most new cases are occurring among people who have been taking care of sick relatives or who have prepared an infected body for burial.
Health care workers are at high risk, especially if they have not been properly equipped with or trained to use and decontaminate protective gear correctly.
The virus can survive on surfaces, so any object contaminated with bodily fluids, like a latex glove or a hypodermic needle, may spread the disease.
Instead, Ebola spreads through direct contact with bodily fluids. If an infected person’s blood or vomit gets in another person’s eyes, nose or mouth, the infection may be transmitted. In the current outbreak, most new cases are occurring among people who have been taking care of sick relatives or who have prepared an infected body for burial.
Health care workers are at high risk, especially if they have not been properly equipped with or trained to use and decontaminate protective gear correctly.
The virus can survive on surfaces, so any object contaminated with bodily fluids, like a latex glove or a hypodermic needle, may spread the disease.
Why is Ebola so difficult to contain?
The epidemic is growing faster than efforts to keep up with it, and
it will take months before governments and health workers in the region can get
the upper hand, according to Doctors Without Borders.
How does Ebola compare with other infectious diseases in the news?
The biggest headlines have tended to involve outbreaks of deadly
viruses that medical workers have few, if any, tools to combat. The four most
prominent are compared below. No cure is known for any of them, nor has any
vaccine yet been approved for human use.
Ebola
|
Marburg
|
MERS
|
SARS
|
|
Emerged / identified
|
1976;
latest outbreak in 2014
|
1967;
latest major outbreak in 2005
|
2012-2013
|
2002-2003
|
Locus
|
Originally,
Congo Basin and central Africa; latest strain, West Africa
|
Originally,
central Europe; latest major outbreak, Angola
|
Arabian
peninsula
|
Southern
China
|
Suspected
source
|
Fruit
bats, by way of monkeys and other animals
|
Fruit
bats, sometimes by way of monkeys
|
Bats,
by way of camels
|
Bats,
by way of civets
|
Type
of virus
|
Filovirus
|
Filovirus
|
Coronavirus
|
Coronavirus
|
Type
of illness
|
Hemorrhagic
fever
|
Hemorrhagic
fever
|
Respiratory
syndrome
|
Respiratory
syndrome
|
Fatality
rate in outbreaks
|
50%
to 90%
|
24%
to 88%
|
About
30%
|
About
10%
|
Known
cases
|
4,000+
|
570+
|
830+
|
8,200+
|
Known
deaths
|
2700+
|
470+
|
290+
|
775+
|
Person-to-person
transmission
|
Readily
by close contact or fluids; not by aerosol
|
Readily
by close contact or fluids; not by aerosol
|
Not
very readily; mechanism unclear
|
Very
readily by aerosol, fluids or close contact
|
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