Medical symbol - African parasite?

Kimo Morris morrisk at bcc.orst.edu
Tue Nov 19 20:10:12 EST 1996


Howes Christopher J wrote:
> 
>   Hi, I don't know if anyone can help me, but any input would be greatly
> appreciated.  I need some information on the link between the medical
> symbol (staff with 2 intertwining snakes) and an African parasitic
> disease.  This is for a contest I can win a t-shirt for.  They are looking
> for how the symbol evolved, and why it did.
> 
>   Sorry if this is offtopic, but I don't know where else to ask.  Any
> other references would be greatly appreciated as well.
> 

As others have noted in this thread, the caduceus (medical symbol) is 
not a staff with snakes, but rather guinea worms (Dracunculus 
medinensis) wrapped on a removal device.  The reason these little 
critters were adopted by the medical profession as their symbol is 
because Dracunculiasis represents one of the first "treatable" parasitic 
afflictions of man.  It was one of the first endosomatic parasites that 
was removable by primative means, i.e. non-surgical.  We now know a 
whole lot more about these worms than we did 100 years ago.  

Pathology is caused by the female worm, which bores through the skin of 
its human host (usually in the extremities such as the legs) where her 
uterus will rupture, spewing forth thousands of eggs.  When these eggs 
contact a water source, such as a well, they will hatch releasing a tiny 
larva that must be eaten by the intermediate host in the life cycle, the 
cyclopid freshwater copepod, Cyclops sp.  After being swallowed by the 
copepod, the worm will bore through the gut lining and will enter the 
body cavity where it will mature and will simply wait.  The life cycle 
is completed when a human drinks unfiltered water and swallows the 
copepod, thus releasing the worm into the gut.  The worm will bore 
through the gut lining and enter the subcutaneous tissue where it will 
further mature.  Males are small (3mm) while females can reach a meter 
in length.  After mating, the male dies and the female migrates to the 
extremities to release her eggs.  

An interesting consequence of the males dying in the human:  there is a 
mild elephantiasis effect in people with heavy infections since dead 
males will clog lymphatic flow.

Some historical notes:  Dracunculus ("little dragon") has been known 
since biblical times, and is actually referred to as the "fiery serpent" 
in the bible; reason being, one of the symptoms is intense itching and 
burning of the ulcerated region.

Some key references:

Poinar, G.O., 1983, The Natural History of Nematodes, Prentice-Hall, 
Inc., Englewood Cliffs, New Jersey.

Noble & Noble, 199?, Parasitology, ???

Schmidt and Roberts, 199?, Parasitology, ???

Also, the WHO does report the prevalence of these cases on their web 
page.

If you need more info, let me know, and I'll see what I can dig up.

-- Kimo

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