MadSci Network: Virology

Subject: RE: Ebola Virus

Posted by Tom Wilson
Grade level: M.D./PhD, Pathology, Div. of Molecular Oncology, Washington University Medical School
City: State/Province:
Area of science: Virology
Ah, good!  I always appreciate the chance to dispel some of the myths that

exist about the Ebola virus!

Question 1:  Ebola does NOT cause the body to liquefy!  I wish I knew 
where this description of the disease comes from.  Ebola does cause a 
large degree of tissue destruction in many parts of the body.  We call 
this tissue destruction "inflammation".  But it is fundamentally no 
different than the kind of destruction that occurs in, say, the common 
cold.  This is exactly how your body fights the infection.  Unfortunately, 
the inflammation can sometimes hurt you as much as it helps fight the 
infection.  Part of inflammation is that tissues become leaky to fluid 
(why your nose runs), and this is compounded in Ebola infection since the 
virus is infecting (and killing) the cells of the blood vessels (see below), 
and so there is an even greater leakiness that results in frank bleeding.  
This results in the very powerful image of an infected person, since they 
have a bloody drainage at the eyes, nose, mouth, etc., and leads to the name 
for this disease, which is "hemorrhagic (i.e. bleeding) fever".  But this 
idea that the internal organs turn to liquid is absurd.  They are merely 
having the same kind of inflammation occurring, which does cause fluid 
accumulation and severe tissue destruction, but again, it is nothing as 
fanciful what you have been led to believe.

As for the clotting, part of the bodies normal response to a damaged 
blood vessel is to form a clot there, to stop the bleeding.  A clot is a 
solidification of the the liquid components of blood, and is thus a 
fundamentally different process from the inflammation that is causing the 
fluid leakiness.

Question 2:  Ebola virus does NOT infect every cell in the body!  Again, 
I wish I knew where this idea came from.  Ebola infects almost exclusively 
the cells that line the insides of your blood vessels - we call them 
"endothelial cells".  Since all parts of your body have blood vessels, 
of course, all *parts* of the body (skin, organs, brain, etc.) can get 
infected.  This is certainly part of why Ebola infection is so severe - 
by infecting only one cell type, the whole body can be damaged.  It is 
also part of  why Ebola can spread about the body so quickly - as soon 
as virus gets released from a dying cell, it finds itself in the bloodstream 
where it can now be pumped all over the body very fast.

As far as Ebola being a filovirus - it is called this simply because 
it shares certain features with some related viruses - the details are 
not important.  But like all viruses, what Ebola has to do is to get 
into the body, bind to the surface of the cell it infects, get into the 
cell, make more of the virus, and then get back out of the cell to start 
the cycle over again (which for most viruses kills the cell).  This 
process is certainly fascinating, but Ebola is not doing anything 
fundamentally different than any other virus.

Question 3:  I'm not sure I understand your question.  IF you are asking, 
"do virus-infected cells start attacking the other cells in the body?" 
then the answer is definitely not.  Infected cells do two things - make 
more virus and die.  IF you are asking, do some cells in the body 
recognize the infection and then start attacking (i.e. damaging) the body, 
then the answer is, in a sense, yes.  This is precisely the "inflammation"
I mentioned above.  The cells of the immune system try to fight the infection 
by damaging and killing the infected cells.  But as a necessary consequence 
of this, some of the nearby normal tissue also gets damaged.  This is normal, 
and a good thing, since again it is how your body fights all infections.

Question 4:  Ebola is most definitely NOT related to the Bubonic plague.  
Ebola is a virus.  The plague was caused by a kind of bacteria called 
Yersinia pestis.  I don't know how much you know about the difference 
between viruses and bacteria, and I don't have nearly enough space to 
detail this, but they are completely different kinds of infectious agents.  

More importantly, you need to understand that the "Bubonic plague" has 
NOT been dormant for hundreds of years.  This bacteria still exists in 
a lot of animal populations, and occasionally humans still get infected 
(there was a relatively recent small outbreak in India (or was it Pakistan?)).
The main reason the epidemic or "plague" is long over is that we now know how 
people were getting infected (from the fleas that were on all the rats) - 
get rid of the rats, get rid of the plague.  The point is this - it is far 
easier for an infectious agent to cause a huge epidemic if the mode of 
infection is "silent" or unknown.  Ebola infection is very obvious - people 
are very sick, and they look it.  The likelihood that a single infected 
person could start a worldwide infection is limited, since frankly you 
wouldn't go anywhere near that person.  AIDS is a thousand times scarier, 
since you never know when the person you are having sex with is infected.  
It is for this reason that I strongly encourage you to discuss with your 
parents, teachers and friends how to keep yourself from getting AIDS!!!

Question 5:  Ebola is most definitely NOT related to leprosy.  Leprosy is 
caused by a bacteria called Mycobacterium leprae, and so is not at all 
related to the Ebola virus.

If there is one thing I want you to learn from all of this, it is the 
following - BE SKEPTICAL!  Dont believe everything you read!  I applaud 
you for trying to find out the "real answers" behind some of these myths 
about Ebola.  And I hope you see that just because someone says it in a 
magazine or in a movie ("Outbreak" was terribly misleading from a scientific 
standpoint) doesn't make it true.  The only way you will get to the real 
answer is by thinking skeptically, applying a good scientific thought process, 
and learning as much as you can about the facts, not people's opinions 
(you shouldn't even automatically believe my opinions!!).  

Best of luck, and I hope this helps.

Tom Wilson , MD PhD

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