Ebola/Marburg

[Bill Graney]

"W. Bruce LeFebvre" <STUDley at ix.netcom.com> wrote:


>I have just read Richard Preston's book "The Hot Zone" which gives a 
>history of what is known of the Ebola virus and the investigations that 
>were made in Kitum Cave near Mt. Elgon in Africa.
>
>I am not a research scientist, however, I am struck by the similarities 
>of what happens to a victim of Ebola or Marburg.  They seem to "dissolve"
>internally into a primordial soup of nutrients.
>
>Isn't this exactly what happens when a spider injects its venom into prey 
>or an attacker?  Usually they're insects that have gotten into any 
>particular spider's trap (web) and the spider bites it and then waits for 
>the venom to perform its duties.  This, of course, happens in nature and 
>everyone accepts it.  What happens, however, when the particular enzyme 
>in a spider's venom somehow attaches itself to the DNA of one of its 
>native viruses?  Perhaps in response to a change in the availability of 
>its historic prey wherein it is forced to feed on larger prey which needs 
>a vehicle in order to liquify its victims.
>
>While I realize a great effort was made to identify the host agent for 
>the viruses, no one seemed to suggest the similarity between spider 
>feeding methods and the "crash and bleedout" response of victims of 
>Marburg and Ebola. The most obvious similarity to me is the fact that
>when the disease has advanced to the terminal stage, the victim's 
>connective tissue seems to dissolve and there is no "glue" to hold the 
>internal organs together.  Isn't this what happens to spider prey so the 
>spider can drink the soup of nutrients from its victims?
>
>It can't be that the collective scientific world hasn't thought of this.
>How come I've never read anything about it?
>

Bill Graney replies:


Gentleperson,

You may be confusing some of the "hot language" used in the "Hot Zone" 
with an accurate description of the pathophysiology of these diseases.  A 
diffuse process of thrombosis and damage to blood vessels leads to 
extensive tissue death and the effects described loosely as "melting." 
The Ebola and Marburg viruses are quite capable of producing these 
effects without the need for additional vectors or pathogens.

You're right about the effects of spider venom in invertebrate prey.  
Within the relatively open body cavity of these organisms, enzymes can 
diffuse and cause extensive liquifaction and preparing the spider's 
liquid meal. With the more compartmentalized body structure of 
vertebrates, such a widespread effect would be unlikely.  Certainly small 
areas of necrosis are noted at the site of the bite, but the only 
systemic effects are much more discrete and don't approach liquifaction.

I would encourage you to pursue your interest in these diseases by 
working toward a solid understanding of the exciting science involved 
with these emerging diseases. Try "The Coming Plague: Emerging Diseases 
in a World Out of Balance by Laurie Garrett,  this is a somewhat more 
scientific approach to Ebola and other important emerging diseases, now 
available in paperback.  Also, try the CDC Website, where you can get 
copies of the excellent Journal of Emerging Diseases in .pdf format and 
get copies of the Weekly Morbidity and Mortality Weekly Report. (Most of 
the public health stories you see on TV are taken from these reports!)

We need all the educated citizens we can get.  Keep reading, keep 
posting.  Welcome.

Yours,

Bill Graney